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--- wearmouth:version_2 [2022/03/22 09:24] – created evert
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+<HTML>
+<pre>
+; Disassembly of the file "C:\lab\if1-2.rom"
+;
+; CPU Type: Z80
+;
+; Created with dZ80 1.50
+;
+; on Sunday, 28 of April 2002 at 12:35 PM
+;
+; ------------------------
+; last updated 14-JAN-2004
+; ------------------------
+#define DEFB .BYTE
+#define DEFW .WORD
+#define DEFM .TEXT
+#define EQU  .EQU
+#define ORG  .ORG
+        ORG     $0000
+; ---------------------------------------
+; FLAGS3 System Variable - IY+$7C ($5CB6)
+; ---------------------------------------
+; Bit 0 - set when executing an extended command.
+; Bit 1 - set during CRT-VARS and CLEAR #, CLOSE etc.
+; Bit 2 - settable by User to force the ERR_SP routine to handle errors.
+; Bit 3 - set when networking.
+; Bit 4 - set during LOAD and MOVE
+; Bit 5 - set during SAVE
+; Bit 6 - set during MERGE
+; Bit 7 - set during VERIFY
+;
+; <font color=#9900FF>Note.</font> before initialization of FLAGS_3, this is considered to be the first
+; byte of channels and so PEEK 23734 gives 244 decimal (%11110100) the high
+; order byte of the Main ROM address PRINT-OUT - $09F4.
+;
+; -------------------------------------------
+; --------------------------------
+; THE <b><font color=#333388>'RETURN TO MAIN ROM'</font></b> ROUTINE
+; --------------------------------
+;   The system is initialized by the Main ROM so this address is accessed
+;   solely by a RST 00H instruction.  It is used from five locations to return
+;   to the Main ROM.
+<a name="L0000"></a>;; <b>MAIN-ROM</b>
+L0000:  POP     HL              ; discard the return address in this ROM.
+        LD      (IY+$7C),$00    ; reset all the bits of FLAGS_3.
+        JP      <A href="#L0700">L0700</a>           ; jump forward to UNPAGE address.
+; -------------------
+; THE <b><font color=#333388>'START'</font></b> ROUTINE
+; -------------------
+;   An instruction fetch on address $0008 pages in this ROM.
+;   The three-byte instruction at this location must exist on both sides of
+;   the looking-glass.  The value fetched is immediately discarded.
+;   It follows that this restart should never be invoked from this ROM.
+<a name="L0008"></a>;; <b>ST-SHADOW</b>
+L0008:  LD      HL,($5C5D)      ; fetch character address from CH_ADD.
+        POP     HL              ; pop return address to HL register.
+        PUSH    HL              ; and save again on machine stack.
+        JP      <A href="#L009A">L009A</a>           ; jump forward to continue at START-2.
+; -----------------------------
+; THE <b><font color=#333388>'CALL A MAIN ROM'</font></b> ROUTINE
+; -----------------------------
+;   Call an address in the main ROM. The address follows the restart so this
+;   is as convenient and as brief as a CALL instruction.
+;   The SBRT routine within the system variables area reads
+;
+;   L5CB9         LD      HL,value
+;   L5C5C         CALL    addr
+;   L5C5F         LD      (L5CB9+1),HL
+;   L5CC2         RET
+;
+;   By immediately placing the current value of HL in the subroutine, then
+;   all registers before the call are as they were before the RST
+;   instruction.  The value of HL after the call is stored immediately in
+;   this now redundant location so that, after this ROM is paged back in,
+;   the registers, after the RST instruction has executed, are as they were
+;   immediately after the CALL.
+;   see START-2.
+<a name="L0010"></a>;; <b>CALBAS</b>
+L0010:  LD      ($5CBA),HL      ; insert the current value of HL in the
+                                ; Z80 code to be picked up later.
+        POP     HL              ; drop the return address - the location
+                                ; of address to be called.
+        PUSH    DE              ; preserve the DE register contents.
+        JR      <A href="#L0081">L0081</a>           ; forward to continue at CALBAS-2.
+        DEFB    $FF             ; unused.
+; ---------------------------------------------
+; THE <b><font color=#333388>'TEST IF SYNTAX IS BEING CHECKED'</font></b> ROUTINE
+; ---------------------------------------------
+;   On the ZX80, testing the syntax flag was done with the 4-byte
+;   instruction that tests the System Variable FLAGS.  On the ZX81 and
+;   ZX Spectrum, a call to SYNTAX-Z reduced the invocation to a three-byte
+;   CALL.   Here it is reduced to a one-byte restart.
+<a name="L0018"></a>;; <b>CHKSYNTAX</b>
+L0018:  BIT     7,(IY+$01)      ; test most significant bit of FLAGS
+        RET                     ; return the result.
+                                ; (Z = Syntax, NZ = Run-time)
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+; --------------------------
+; THE <b><font color=#333388>'SHADOW-ERROR'</font></b> ROUTINE
+; --------------------------
+;   This is similar to the Main ROM error handler and the following byte
+;   indicates the type of error and in runtime the message that should be
+;   printed.  If checking syntax then the error pointer is set before a
+;   return is made to the Main ROM.
+<a name="L0020"></a>;; <b>SH-ERR</b>
+L0020:  RST     18H             ; checking syntax ?
+        JR      Z,<A href="#L0068">L0068</a>         ; forward, if so, to ST-ERROR
+        JR      <A href="#L003A">L003A</a>           ; forward, in run-time, to TEST-SP,
+                                ; and then REP-MSG
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+; ------------------------------------
+; THE <b><font color=#333388>'MAIN ROM ERROR RESTART'</font></b> ROUTINE
+; ------------------------------------
+;   This restart invokes the error handler of the Main 16K ROM.  The required
+;   error number is usually first placed in the System Variable ERR_NR.  In
+;   some cases the error code is already present and this restart is used when
+;   the error situations handled by this ROM have been eliminated.
+;   Since the exit from this point is by manipulating the stack, the return
+;   address is of no importance as that route is never taken.  There are also
+;   three conditional jumps back to this point.
+<a name="L0028"></a>;; <b>ROMERR</b>
+L0028:  RES     3,(IY+$02)      ; update TV_FLAG - signal no change in mode.
+        JR      <A href="#L0040">L0040</a>           ; forward to RMERR-2.
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+; -------------------------------------------------
+; THE <b><font color=#333388>'CREATE NEW SYSTEM VARIABLES RESTART'</font></b> ROUTINE
+; -------------------------------------------------
+;    This restart is used the first time that that the ROM is paged in to
+;    create the System Variables.  This will be either by an instruction
+;    fetch on $0008 or $1708.
+<a name="L0030"></a>;; <b>NEWVARS</b>
+L0030:  JP      <A href="#L01F7">L01F7</a>           ; jump to CRT-VARS
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+        DEFB    $FF             ; unused.
+; --------------------------------
+; THE <b><font color=#333388>'MASKABLE INTERRUPT'</font></b> ROUTINE
+; --------------------------------
+;   There is no service routine but should the routine be called either
+;   directly or by straying into a RST $38 instruction, then interrupts are
+;   enabled.
+<a name="L0038"></a>;; <b>INT-SERV</b>
+L0038:  EI                      ; Enable Interrupts
+        RET                     ; return.
+; ------------------------
+; THE <b><font color=#333388>'TEST SYSTEM'</font></b> BRANCH
+; ------------------------
+;   This branch allows the user to trap errors before this ROM is used to print
+;   the error report.
+<a name="L003A"></a>;; <b>TEST-SP</b>
+L003A:  CALL    <A href="#L0077">L0077</a>           ; routine CHECK-SP
+                                ; usually returns.
+        JP      <A href="#L0260">L0260</a>           ; jump to REP-MSG
+; ----------------------------
+; THE <b><font color=#333388>'MAIN ROM ERROR'</font></b> ROUTINE
+; ----------------------------
+;   a continuation of RST 28H.
+;   This ROM has inserted a Main ROM error code into ERR_NR and the routine in
+;   the Main ROM is now invoked.
+;   First a check is made to see if the user wishes to trap errors using a
+;   custom routine in ERR_SP.  This will be used in the syntax path anyway.
+;
+<a name="L0040"></a>;; <b>RMERR-2</b>
+L0040:  RST     18H             ; checking syntax ?
+        JR      Z,<A href="#L0068">L0068</a>         ; forward, if so, to ST-ERROR.
+        CALL    <A href="#L0077">L0077</a>           ; routine CHECK-SP allows the user to trap
+                                ; run-time errors at this point but normally
+                                ; returns here.
+        CALL    <A href="#L17B7">L17B7</a>           ; routine RCL-T-CH reclaims any temporary
+                                ; channels and stops all microdrive motors.
+        BIT     1,(IY+$7C)      ; test FLAGS_3.
+        JR      Z,<A href="#L0068">L0068</a>         ; forward, if executing CLOSE, to ST-ERROR.
+        BIT     4,(IY+$7C)      ; test FLAGS_3 - loading filename 'run' ?
+        JR      Z,<A href="#L0068">L0068</a>         ; forward, if not, to ST-ERROR.
+;   As a security measure, the file 'run' can not be hacked.
+        LD      A,(IY+$00)      ; fetch error number from the System Variable
+                                ; ERR_NR.
+        CP      $14             ; is it "CODE error" ?
+        JR      NZ,<A href="#L0068">L0068</a>        ; forward, if not, to ST-ERROR.
+;   The user has pressed BREAK while trying to load the program 'run'.
+        LD      HL,$0000        ; cause a system reset.
+        PUSH    HL              ; place address zero on machine stack.
+        RST     00H             ; switch to MAIN-ROM.
+;
+        DEFB    $FF             ; unused
+        DEFB    $FF             ; unused
+        DEFB    $FF             ; unused
+        DEFB    $FF             ; unused
+        DEFB    $FF             ; unused
+; ------------------------------------
+; THE <b><font color=#333388>'NON-MASKABLE INTERRUPT'</font></b> ROUTINE
+; ------------------------------------
+;   There is no NMI functionality.
+<a name="L0066"></a>;; <b>NMINT-SRV</b>
+L0066:  RETN                    ; return to previous interrupt state.
+; --------------------------
+; THE <b><font color=#333388>'SYNTAX ERROR'</font></b> ROUTINE
+; --------------------------
+;   An error has occurred during syntax checking so the position must be
+;   highlighted when a return is made to the Editor in the Main ROM.
+<a name="L0068"></a>;; <b>ST-ERROR</b>
+L0068:  LD      HL,($5C5D)      ; fetch character address from CH_ADD.
+        LD      ($5C5F),HL      ; set X_PTR to same to position error cursor.
+        LD      SP,($5C3D)      ; set the Stack Pointer from ERR_SP.
+        LD      HL,$16C5        ; prepare address of main SET-STK.
+        PUSH    HL              ; push on the machine stack.
+        RST     00H             ; switch to MAIN-ROM where SET-STK will clean up
+                                ; the work areas before returning to the Error
+                                ; Routine obtained from ERR_SP.
+; ---------------------------------------
+; THE <b><font color=#333388>'CHECK ERROR STACK POINTER'</font></b> ROUTINE
+; ---------------------------------------
+;   This allows the user's software to trap any errors at this point by setting
+;   the otherwise unused bit 2 of FLAGS_3 after inserting a custom error
+;   handler in the System Variable ERR_SP.
+;   Both Shadow ROM situations and Main ROM situations can be trapped and the
+;   routine is called from BOTH RST 20H and RST 28H.
+<a name="L0077"></a>;; <b>CHECK-SP</b>
+L0077:  BIT     2,(IY+$7C)      ; test FLAGS_3 has the user set up a custom
+                                ; error handler in Main RAM ?
+        RET     Z               ; return if not.
+;   Otherwise the user, or the third party software, has set up a custom routine
+;   in the system variable ERR_SP and set bit 2 of FLAGS_3 so that it is invoked
+;   at this point.
+        LD      SP,($5C3D)      ; set stack pointer from ERR_SP.
+        RST     00H             ; switch to MAIN-ROM.
+; ----------------------
+; THE <b><font color=#333388>'CALBAS-2'</font></b> ROUTINE
+; ----------------------
+;   A continuation of the code at $0010.
+;   Continue by picking up the address to be called, located after the RST
+;   instruction and placing after the CALL instruction in the SBRT sequence.
+<a name="L0081"></a>;; <b>CALBAS-2</b>
+L0081:  LD      E,(HL)          ; fetch low byte of called address
+        INC     HL              ; advance pointer.
+        LD      D,(HL)          ; fetch high byte.
+        LD      ($5CBD),DE      ; place in the Z80 code SBRT
+        INC     HL              ; increment pointer.
+        EX      (SP),HL         ; transfer continuation address to machine
+                                ; stack - and the stack value (was DE) to HL.
+        EX      DE,HL           ; original DE value now restored.
+        LD      HL,$0000        ; signal CALBAS routine in use.
+        PUSH    HL              ; place on stack.
+        LD      HL,$0008        ; address of main ERROR restart
+        PUSH    HL              ; place on stack
+        LD      HL,$5CB9        ; address of calling SBRT subroutine.
+        PUSH    HL              ; place on stack.
+        JP      <A href="#L0700">L0700</a>           ; jump to UNPAGE
+; ---------------------
+; THE <b><font color=#333388>'CONTROL'</font></b> ROUTINE
+; ---------------------
+;   A continuation of code at L0008. The return address has been dropped off
+;   the machine stack into HL.
+;
+;   First see if this ROM was paged in as a result of the $0008 address
+;   stacked during the CALBAS routine. (see above)
+<a name="L009A"></a>;; <b>START-2</b>
+L009A:  PUSH    AF              ; preserve accumulator and status flags.
+        LD      A,H             ; test HL for zero - the CALBAS
+        OR      L               ; indicator value.
+        JR      NZ,<A href="#L00A5">L00A5</a>        ; forward, if not, to START-3.
+        POP     AF              ; restore accumulator and flags.
+        POP     HL              ; discard address stacked by RST 08.
+        LD      HL,($5CBA)      ; pick up post-CALL HL value from SBRT.
+        RET                     ; return.
+;------------------------------------------------------------------------------
+;   Now consider that the address $0008 may have been an input or output
+;   routine that precedes the letter of one of the new channels.  These
+;   paging addresses ensure that this ROM is paged in so that the real
+;   input/output addresses can be read from the locations after the
+;   channel's letter. In this case, the return address is towards the end
+;   of the CALL-SUB routine in the Main ROM, i.e.
+;   L15FB         CALL    $162C   ; routine CALL-JUMP (a JP (HL) instr.)
+;   L15FE         POP     HL      ; return address
+;------------------------------------------------------------------------------
+<a name="L00A5"></a>;; <b>START-3</b>
+L00A5:  PUSH    DE              ; preserve DE.
+        LD      DE,$15FE        ; test against possible return address 0x15FE
+        SBC     HL,DE           ; subtract (carry is clear)
+        POP     DE              ; restore DE.
+        JR      NZ,<A href="#L00BC">L00BC</a>        ; forward with no match to START-4.
+;   This ROM has been paged by an attempt to use a stream.
+        POP     AF              ; restore accumulator.
+        LD      HL,<A href="#L0700">L0700</a>        ; stack the address UNPAGE to switch to
+        PUSH    HL              ; the Main ROM afterwards.
+        LD      HL,$0004        ; the shadow routine is 4 bytes forward
+        ADD     HL,DE           ; adjust input/output address pointer.
+        LD      E,(HL)          ; pick up low-order byte of I/O routine.
+        INC     HL              ; bump pointer.
+        LD      D,(HL)          ; pick up high-order byte of routine.
+        EX      DE,HL           ; transfer I/O address to HL.
+        JP      (HL)            ; jump to routine and then to UNPAGE
+; ---
+;   By elimination, the address $0008 has been reached as a result of a
+;   RST 08 instruction in the Main ROM.  This may be the very first time
+;   that this ROM has been paged in after startup or NEW.
+<a name="L00BC"></a>;; <b>START-4</b>
+L00BC:  RST     30H             ; create new system variables if first time.
+        LD      A,$01           ; %00000001
+        OUT     ($F7),A         ;
+        LD      A,$EE           ; %11101110
+        OUT     ($EF),A         ;
+        POP     AF              ; temporarily drop the accumulator.
+        POP     HL              ; fetch address of error code/hook code to HL.
+        PUSH    AF              ; save accumulator again.
+;   <font color=#9900FF>Note.</font> the address of the code could be anywhere in the 64K address space
+;   but it is not in this ROM.  Luckily in the Main ROM at $007B is the
+;   sequence ld a,(hl) ; ret which will fetch the unknown error code from
+;   the known address.
+        RST     10H             ; CALBAS
+        DEFW    $007B           ; main TEMP-PTR3
+        LD      ($5C3A),A       ; place the error code in sysvar ERR_NR
+;   The error code at this stage is one less than actual code.
+        CP      $FF             ; is it 'OK'
+        JR      NZ,<A href="#L00E9">L00E9</a>        ; forward, if not, to TEST-CODE
+        BIT     1,(IY+$7C)      ; test FLAGS_3  - first time ?
+        JR      Z,<A href="#L00E7">L00E7</a>         ; forward, if not, to NREPORT-2
+                                ; 'Program finished'
+        BIT     7,(IY+$0C)      ; test PPC_hi - a direct command ?
+        JR      Z,<A href="#L00E7">L00E7</a>         ; forward, if not, to NREPORT-2
+        LD      HL,($5C59)      ; use E_LINE to address the first character of
+                                ; the edit buffer.
+        LD      A,(HL)          ; searching for RUN without whitespace.
+        CP      $F7             ; is character the token 'RUN' ?
+        JP      Z,<A href="#L0A99">L0A99</a>         ; jump forward, if so, to LOAD-RUN
+<a name="L0663"></a>;; <b>NREPORT-2</b>
+L00E7:  RST     20H             ; Shadow Error Restart
+        DEFB    $FF             ; 'Program finished'
+; ---
+;   Continue to consider the error code.  This may have occurred after the
+;   Error RESTART in the Main ROM - range $00 (NEXT without FOR) to
+;   $1A (Tape Loading Error) or a RESTART in RAM which could also include
+;   the Hook Codes.
+<a name="L00E9"></a>;; <b>TEST-CODE</b>
+L00E9:  SUB     $1B             ; subtract lowest Hook Code (PAUSE)
+        JP      NC,<A href="#L1E71">L1E71</a>        ; jump, if same or higher, to HOOK-CODE
+        CP      $F0             ; was it $0B 'Nonsense in basic'
+        JR      Z,<A href="#L00FB">L00FB</a>         ; forward to COPYCHADD
+        CP      $F3             ; was it $0D 'Invalid file name'
+        JR      Z,<A href="#L00FB">L00FB</a>         ; forward to COPYCHADD
+        CP      $FC             ; was it $17 'Invalid stream'
+        JP      NZ,<A href="#L0028">L0028</a>        ; jump, if not, to ROMERR
+;   If one of the above three reports, then this is possibly an extended
+;   command and further investigation is required. A number of situations
+;   may apply. The error could have occurred -
+;
+;   1) In INPUT - just pass control back to Main ROM. This is just a normal
+;      Nonsense in BASIC and will not be due to anything new.
+;   2) While already investigating an error. Too much - just use Main ROM.
+;   3) While entering a new or modified line and syntax failed.
+;   4) While running the program and an error was encountered.
+;
+;   The character address CH_ADD is not much use as that is the place
+;   after the command where the standard ROM encountered an error.
+;   It will be required by the Main ROM if control is passed back so, in
+;   order that the Main ROM parsing routines can be used, make a copy of the
+;   error character position. We will have to work forward from the
+;   beginning of the line if checking syntax or from the start of the
+;   program in run-time so that the errant command can be found. It may also
+;   be necessary to remove hidden characters from the BASIC line.
+<a name="L00FB"></a>;; <b>COPYCHADD</b>
+L00FB:  LD      HL,($5C5D)      ; fetch character address from CH_ADD and
+        LD      ($5CCB),HL      ; store in shadow system variable CHADD_
+        POP     AF              ; restore accumulator.
+        BIT     5,(IY+$37)      ; test FLAGX - in INPUT mode ?
+        JP      NZ,<A href="#L0028">L0028</a>        ; jump back, if so, to ROMERR
+;   Continue if in Editing or Run-time Mode.
+        BIT     0,(IY+$7C)      ; test FLAGS_3 - already extended command ?
+        JP      NZ,<A href="#L0028">L0028</a>        ; jump, if so, to ROMERR
+;   else signal - handling an extended command - so that such a double error
+;   can be trapped.
+        SET     0,(IY+$7C)      ; update FLAGS_3 - signal executing an
+                                ; extended command.
+        RST     18H             ; checking syntax ?
+        JR      NZ,<A href="#L011B">L011B</a>        ; skip forward, if not, to RUNTIME
+        LD      (IY+$0C),$FF    ; set bit 7 of PPC_hi to indicate a line
+                                ; entry situation.
+;    In both cases, load B with the statement number where the error was
+;    encountered.  Previous validated statements are not to be disturbed.
+<a name="L011B"></a>;; <b>RUNTIME</b>
+L011B:  LD      B,(IY+$0D)      ; load B with statement number from SUBPPC
+        LD      C,$00           ; and set C to zero for a quotes flag.
+        BIT     7,(IY+$0C)      ; test PPC_hi - line entry ?
+        JR      Z,<A href="#L0130">L0130</a>         ; forward, if not, to PROG-LINE
+;   An edit line may have a line number at start and whitespace. We need to
+;   set CH_ADD at the first command.
+        PUSH    BC              ; save BC
+        RST     10H             ; CALBAS
+        DEFW    $19FB           ; main E-LINE-NO fetches any line number to
+                                ; BC, setting CH_ADD at the command token.
+        POP     BC              ; restore BC - discarding line number.
+        RST     10H             ; CALBAS
+        DEFW    $0018           ; main GET-CHAR gets first command of the
+                                ; first statement of the errant line.
+        JR      <A href="#L016F">L016F</a>           ; forward to statement loop - S-STAT to find
+                                ; the errant statement.
+; ---
+<a name="L0130"></a>;; <b>PROG-LINE</b>
+L0130:  LD      HL,($5C53)      ; set pointer to start of program from PROG.
+<a name="L0133"></a>;; <b>SC-L-LOOP</b>
+L0133:  LD      A,($5C46)       ; fetch high byte of errant line from PPC_hi
+        CP      (HL)            ; compare with tested high byte.
+        JR      NC,<A href="#L013B">L013B</a>        ; forward, if errant line higher or same,
+                                ; to TEST-LOW
+; else, unusually, the current line is not there so let Main ROM handle.
+<a name="L0139"></a>;; <b>NREPORT-1</b>
+L0139:  RST     20H             ; Shadow Error Restart
+        DEFB    $00             ; Nonsense in BASIC
+; ---
+<a name="L013B"></a>;; <b>TEST-LOW</b>
+L013B:  INC     HL              ; increment program pointer to address low byte.
+        JR      NZ,<A href="#L0144">L0144</a>        ; forward, if high bytes not same, to LINE-LEN
+        LD      A,($5C45)       ; fetch low byte of current line from PPC_lo
+        CP      (HL)            ; compare to addressed byte.
+        JR      C,<A href="#L0139">L0139</a>         ; back, if not in program area, to NREPORT-1
+<a name="L0144"></a>;; <b>LINE-LEN</b>
+L0144:  INC     HL              ; increment program
+        LD      E,(HL)          ; pointer and
+        INC     HL              ; pick up the
+        LD      D,(HL)          ; length of the BASIC line
+        INC     HL              ; resting at the first character.
+        JR      Z,<A href="#L016F">L016F</a>         ; forward, if line numbers matched, to S-STAT
+                                ; the mid-entry point of the statement loop.
+        ADD     HL,DE           ; else add length to current address.
+        JR      <A href="#L0133">L0133</a>           ; loop back to SC-L-LOOP
+; --------------------
+; THE <b><font color=#333388>'STATEMENT LOOP'</font></b>
+; --------------------
+;    Entered at mid-point S-STAT with statement counter in B and a quotes
+;    counter, C, set at an even zero.
+<a name="L014E"></a>;; <b>SKIP-NUM</b>
+L014E:  LD      DE,$0006        ; a hidden floating point number has six bytes.
+        ADD     HL,DE           ; add to skip to next character.
+; -&gt; The Looping Point.
+<a name="L0152"></a>;; <b>EACH-ST</b>
+L0152:  LD      A,(HL)          ; fetch addressed BASIC character.
+        CP      $0E             ; is it the hidden number indicator ?
+        JR      Z,<A href="#L014E">L014E</a>         ; back to SKIP-NUM to ignore.
+        INC     HL              ; else increase pointer.
+        CP      $22             ; is it quotes character '"' ?
+        JR      NZ,<A href="#L015D">L015D</a>        ; skip forward, if not, to CHKEND
+        DEC     C               ; decrement quotes counter.
+<a name="L015D"></a>;; <b>CHKEND</b>
+L015D:  CP      $3A             ; is character ':' ?
+        JR      Z,<A href="#L0165">L0165</a>         ; skip forward to CHKEVEN
+        CP      $CB             ; is character 'THEN' ?
+        JR      NZ,<A href="#L0169">L0169</a>        ; skip forward to CHKEND-L
+<a name="L0165"></a>;; <b>CHKEVEN</b>
+L0165:  BIT     0,C             ; are quotes balanced ?
+        JR      Z,<A href="#L016F">L016F</a>         ; forward, if so, to S-STAT
+                                ; for next statement.
+;   A carriage return must not appear within quotes.
+<a name="L0169"></a>;; <b>CHKEND-L</b>
+L0169:  CP      $0D             ; carriage return ?
+        JR      NZ,<A href="#L0152">L0152</a>        ; back, if not, to EACH-ST
+        JR      <A href="#L0139">L0139</a>           ; back to NREPORT-1
+                                ; 'Nonsense in BASIC'
+;    The Statement Loop Entry Point --&gt;
+<a name="L016F"></a>;; <b>S-STAT</b>
+L016F:  DJNZ    <A href="#L0152">L0152</a>           ; decrement statement counter and loop back
+                                ; to EACH-ST.
+;    The errant statement has been located and CH_ADD is set to start.
+        DEC     HL              ; point to start or ':'
+        LD      ($5C5D),HL      ; set the Main ROM system variable CH_ADD
+        RST     18H             ; checking syntax ?
+        JR      NZ,<A href="#L01AA">L01AA</a>        ; forward, if not, to CL-WORK
+        BIT     7,(IY+$0C)      ; test PPC_hi - is it an Edit Line ?
+        JP      Z,<A href="#L01F0">L01F0</a>         ; jump forward, if not, to ERR-6.
+        DEC     HL              ; prepare to enter loop below.
+        LD      C,$00           ; ??
+;   It is well to reflect on what has been achieved up to this point.  At
+;   each statement, the first attempt at validation is made by the Main ROM.
+;   Then if that should encounter something not to its liking, this ROM has
+;   a bash.  There could be ten or more statements before this one and each
+;   will have been validated by the Main ROM or by this routine.  As part of
+;   that validation process, when a number is parsed, then the integer or
+;   floating point form of the number is inserted after the digits, rendered
+;   invisible by a CHR$(14).
+;
+;   Once a statement has passed validation by either ROM, then it is not
+;   undone.  If, say, the Main ROM has failed on the third statement of
+;
+;   10 PRINT "Hi :" : LET vat = 15 : OPEN# 7, "T" : LET tax = cost * (vat/100)
+;
+;   then it will have already inserted six bytes after the '7' before raising
+;   the error 'Invalid stream'.  This ROM has located the separator before
+;   the command but needs to remove the hidden numbers before parsing the
+;   statement as the latter process will put them back in and we can't
+;   double up.  The easiest way to do this is to search for hidden numbers
+;   right to the end of the line.  There won't be any after this statement
+;   but stopping at a CHR$(13) is easier than considering end of statement
+;   markers in quotes.  It seems that this neat solution was not arrived at
+;   immediately and the instruction, above, sets C to the quotes flag again
+;   and it is needlessly preserved on the stack.
+;
+;   The end-user is oblivious to this elegant toing and froing between ROMS
+;   and the unseen error code generation and cancellation. All that is
+;   apparent is that when the RETURN key is pressed, the line simply enters
+;   the program.
+<a name="L0182"></a>;; <b>RCLM-NUM</b>
+L0182:  INC     HL              ; increment character pointer
+        LD      A,(HL)          ; fetch the character.
+        CP      $0E             ; is it the number marker ?
+        JR      NZ,<A href="#L01A5">L01A5</a>        ; forward, if not, to NEXTNUM
+        PUSH    BC              ; preserve BC (zero)
+        LD      BC,$0006        ; six bytes to reclaim.
+        RST     10H             ; CALBAS
+        DEFW    $19E8           ; main RECLAIM-2
+        PUSH    HL              ; preserve character pointer.
+        LD      DE,($5CCB)      ; fetch error pointer from CHADD_
+        AND     A               ; prepare for true subtraction.
+        SBC     HL,DE           ; test if character position less than error.
+        JR      NC,<A href="#L01A3">L01A3</a>        ; forward, if not, to NXT-1
+        EX      DE,HL           ; transfer CHADD_ value to HL.
+        LD      BC,$0006        ;
+        AND     A               ;
+        SBC     HL,BC           ; reduce by six.
+        LD      ($5CCB),HL      ; store back in system variable CHADD_
+<a name="L01A3"></a>;; <b>NXT-1</b>
+L01A3:  POP     HL              ; restore character pointer.
+        POP     BC              ; and restore BC (zero)
+<a name="L01A5"></a>;; <b>NEXTNUM</b>
+L01A5:  LD      A,(HL)          ; fetch character.
+        CP      $0D             ; carriage return ?
+        JR      NZ,<A href="#L0182">L0182</a>        ; loop back, if not, to RCLM-NUM
+;  The run-time path rejoins here
+<a name="L01AA"></a>;; <b>CL-WORK</b>
+L01AA:  RST     10H             ; CALBAS
+        DEFW    $16BF           ; main SET-WORK
+        CALL    <A href="#L0255">L0255</a>           ; routine RES-VARS sets new system variables
+                                ; from that following CHADD_ to that preceding
+                                ; COPIES to the value $FF.
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR advances CH_ADD and fetches
+                                ; the command character.
+        SUB     $CE             ; reduce tokens - why?
+        CP      $01             ; 'CAT' ?
+        JP      Z,<A href="#L0486">L0486</a>         ; jump to CAT-SYN
+        CP      $02             ; 'FORMAT' ?
+        JP      Z,<A href="#L04B4">L04B4</a>         ; jump to FRMT-SYN
+        CP      $03             ; 'MOVE' ?
+        JP      Z,<A href="#L053D">L053D</a>         ; jump to MOVE-SYN
+        CP      $04             ; 'ERASE' ?
+        JP      Z,<A href="#L0531">L0531</a>         ; jump to ERASE-SYN
+        CP      $05             ; 'OPEN #' ?
+        JP      Z,<A href="#L04ED">L04ED</a>         ; jump to OPEN-SYN
+        CP      $2A             ; 'SAVE' ?
+        JP      Z,<A href="#L082F">L082F</a>         ; jump to SAVE-SYN
+        CP      $21             ; 'LOAD' ?
+        JP      Z,<A href="#L0898">L0898</a>         ; jump to LOAD-SYN
+        CP      $08             ; 'VERIFY' ?
+        JP      Z,<A href="#L08A2">L08A2</a>         ; jump to VERIF-SYN
+        CP      $07             ; 'MERGE' ?
+        JP      Z,<A href="#L08AC">L08AC</a>         ; jump to MRG-SYN
+        CP      $2D             ; 'CLS' ?
+        JP      Z,<A href="#L0559">L0559</a>         ; jump to CLS#-SYN
+        CP      $2F             ; 'CLEAR' ?
+        JP      Z,<A href="#L057F">L057F</a>         ; jump to CLR#-SYN
+;   If none of the new extended commands then load HL from the VECTOR
+;   system variable which normally points to the error routine below.
+;   However the user, or a third party software publisher, may have
+;   altered the vector to point to their own extended BASIC routines.
+<a name="L01EC"></a>;; <b>ERR-V</b>
+L01EC:  LD      HL,($5CB7)      ; fetch address from system variable VECTOR
+        JP      (HL)            ; jump to address.
+; ---
+<a name="L01F0"></a>;; <b>ERR-6</b>
+L01F0:  LD      HL,($5CCB)      ; fetch original character address from
+                                ; CHADD_
+        LD      ($5C5D),HL      ; and place in standard CH_ADD
+        RST     28H             ; Error Main ROM.
+; -----------------------------------------
+; THE <b><font color=#333388>'CREATE NEW SYSTEM VARIABLES'</font></b> ROUTINE
+; -----------------------------------------
+;   A continuation of the restart code at $0030. A check is made to see if
+;   the 58 variables already exist and the stack is set up to create the
+;   room using the main ROM routine. If there isn't 58 free bytes available
+;   then an 'Out of memory' report is generated by the Main ROM.
+<a name="L01F7"></a>;; <b>CRT-VARS</b>
+L01F7:  LD      HL,($5C4F)      ; system variable CHANS normally   $5CB6.
+        LD      DE,$A349        ; add test value                   $A349.
+                                ;                                   ----
+        ADD     HL,DE           ; add - if uninitialized will give $FFFF.
+        JR      C,<A href="#L023D">L023D</a>         ; forward, if higher, to VAR-EXIST
+        LD      HL,<A href="#L0224">L0224</a>        ; prepare address of DEFAULT routine
+        PUSH    HL              ; push on machine stack
+        LD      HL,($5C63)      ; use system variable STKBOT
+        LD      ($5C65),HL      ; to set system variable STKEND
+        LD      HL,$5C92        ; use system variable MEMBOT
+        LD      ($5C68),HL      ; to set system variable MEM
+        LD      HL,$5CB5        ; the last standard system variable.
+                                ; P-RAMT_hi - the location before new area.
+        LD      BC,<A href="#L003A">L003A</a>        ; 58 bytes to allocate.
+;   Now call MAKE-ROOM in the Main ROM by placing a sequence of addresses
+;   on the machine stack as it is not possible to use the CALBAS routine yet.
+        LD      DE,$0000        ; indicator - signals Main ROM has been used.
+        PUSH    DE              ; stack word.
+        LD      E,$08           ; form address $0008 in Main ROM.
+        PUSH    DE              ; stack word.
+        LD      DE,$1655        ; the Main ROM address MAKE-ROOM.
+        PUSH    DE              ; stack word.
+;   The machine stack now has the hierarchy DEFAULT; $0000; ERROR-1;
+;   MAKE-ROOM which will be handled in reverse order.
+        JP      <A href="#L0700">L0700</a>           ; jump to UNPAGE.
+;   After creating room and paging this ROM back in, 'return' to the next
+;   address which was the first in the sequence pushed on machine stack
+;   earlier.
+<a name="L0224"></a>;; <b>DEFAULT</b>
+L0224:  LD      HL,<A href="#L0242">L0242</a>        ; default system variable values.
+        LD      BC,$0013        ; nineteen bytes to move.
+        LD      DE,$5CB6        ; old CHANS area, new sysvar FLAGS_3.
+        LDIR                    ; copy the bytes.
+;   <font color=#9900FF>Note.</font> So far the value in the accumulator, which may be the number of a
+;   stream to close, has not been altered.  This next instruction is worded
+;   wrongly and
+;
+;   OPEN #7,"s" : CLOSE #7
+;
+;   may not work.
+;   The fix would be to use 'ld hl $5cef ; ld (hl), $01' (5 bytes)
+;   or even 'dec h ; ld ($5cee),hl' (4 bytes)
+;   The next pair of instructions would have been better if executed using
+;   the HL register pair also.
+        LD      A,$01           ; set accumulator to 1.
+        LD      ($5CEF),A       ; set system variable COPIES.
+        LD      (IY+$77),$50    ; set NMI_ADD_hi to eighty.
+        LD      (IY+$76),$00    ; set NMI_ADD_lo to zero.
+        RET                     ; return.
+; ---
+;   The extended System Variables already exist.
+<a name="L023D"></a>;; <b>VAR-EXIST</b>
+L023D:  RES     1,(IY+$7C)      ; reset indicator in FLAGS_3.
+        RET                     ; return.
+; -------------------------------------------
+; THE <b><font color=#333388>'SYSTEM VARIABLES DEFAULT VALUES'</font></b> TABLE
+; -------------------------------------------
+;   These are the initial values of the first section of the extended System
+;   Variables that are copied, once only, to a newly opened area following
+;   the standard 48K Spectrum System Variables.  The memory area that was at
+;   this location (CHANS) is moved upwards to make room.
+;   The first new location (which was the first byte of CHANS) is now
+;   FLAGS_3, accessible by the IY register, and normally zero when the Main
+;   ROM becomes active again.  Bit 1 is set when a CLEAR# is active and also
+;   by the copy itself.
+<a name="L0242"></a>;; <b>SV-DEFS</b>
+L0242:  DEFB    $02             ; FLAGS3 (with bit 1 already set).
+        DEFW    $01F0           ; VECTOR
+        LD      HL,$0000        ; SBRT located at $5CB9
+        CALL    $0000           ;
+        LD      ($5CBA),HL      ;
+        RET                     ;
+        DEFW    $000C           ; BAUD
+        DEFB    $01             ; NTSTAT
+        DEFB    $00             ; IOBORD - black.
+        DEFW    $0000           ; SER_FL
+; ----------------------------------------
+; THE <b><font color=#333388>'RESET NEW SYSTEM VARIABLES'</font></b> ROUTINE
+; ----------------------------------------
+;   The central area is filled with $FF bytes.
+;   This occurs whenever a new extended command is invoked.
+<a name="L0255"></a>;; <b>RES-VARS</b>
+L0255:  LD      HL,$5CCD        ; set pointer to NTRESP - start of area.
+        LD      B,$22           ; thirty four bytes to fill.
+<a name="L025A"></a>;; <b>EACH-VAR</b>
+L025A:  LD      (HL),$FF        ; insert a default $FF value.
+        INC     HL              ; bump the pointer.
+        DJNZ    <A href="#L025A">L025A</a>           ; loop back to EACH-VAR.
+        RET                     ; return.
+; ------------------------------------
+; THE <b><font color=#333388>'SHADOW REPORT PRINTING'</font></b> ROUTINE
+; ------------------------------------
+;   This routine prints the error reports of the Shadow ROM.
+;   These relate to the code that follows a RST 20H restart.  The error code
+;   is not printed as it would conflict with Main ROM reports.  The text of
+;   the message is printed and then the Main ROM routine is used to print a
+;   comma and then the line number and statement.  For example,
+;   Program finished, 0:1
+;   The code is similar to that at MAIN-4 in the Main ROM.  Some improvements
+;   have been made but at least one slight error has been replicated.
+<a name="L0260"></a>;; <b>REP-MSG</b>
+L0260:  LD      (IY+$7C),$00    ; clear FLAGS_3 in preparation for leaving
+                                ; this ROM.
+        EI                      ; Enable Interrupts.
+        HALT                    ; wait for the first interrupt.
+        CALL    <A href="#L17B7">L17B7</a>           ; routine RCL-T-CH reclaims any temporary
+                                ; channels and stops any running drive motor.
+        RES     5,(IY+$01)      ; update FLAGS - 'Ready for new key'.
+        BIT     1,(IY+$30)      ; test FLAGS2 - is printer buffer empty ?
+        JR      Z,<A href="#L0276">L0276</a>         ; forward, if so, to FETCH-ERR
+        RST     10H             ; CALBAS - call a Base ROM routine.
+        DEFW    $0ECD           ; main routine - COPY-BUFF
+                                ; <font color=#9900FF>Note.</font> the programmer has neglected to
+                                ; set bit 1 of FLAGS first.
+<a name="L0276"></a>;; <b>FETCH-ERR</b>
+L0276:  POP     HL              ; drop the return address - after RST.
+        LD      A,(HL)          ; fetch the error code.
+        LD      (IY+$00),A      ; place in system variable ERR_NR.
+        INC     A               ; increment setting zero if was $FF.
+        PUSH    AF              ; save actual code and status flags.
+        LD      HL,$0000        ; prepare to blank some system variables.
+        LD      (IY+$37),H      ; clear all the bits of FLAGX.
+        LD      (IY+$26),H      ; blank X_PTR_hi to suppress error marker.
+        LD      ($5C0B),HL      ; blank DEFADD to signal that no defined
+                                ; function is being evaluated.
+        INC     L               ; select offset of 1 (explicit in main ROM ).
+        LD      ($5C16),HL      ; update STRMS_00 - inputs from keyboard.
+        RST     10H             ; CALBAS
+        DEFW    $16B0           ; main SET-MIN clears workspace etc.
+        RES     5,(IY+$37)      ; update FLAGX - signal in EDIT mode
+                                ; not INPUT mode.
+                                ; <font color=#9900FF>Note.</font> all the bits were reset earlier.
+        RST     10H             ; CALBAS
+        DEFW    $0D6E           ; main CLS-LOWER
+        SET     5,(IY+$02)      ; update TV_FLAG - signal lower screen
+                                ; requires clearing.
+        RES     3,(IY+$02)      ; update TV_FLAG - no change in mode.
+        POP     AF              ; restore the incremented error code.
+        LD      HL,<A href="#L02BF">L02BF</a>        ; start search at REP-MSGS table below.
+        LD      B,$04           ; roughly ensure that BC does not limit
+                                ; search area as code must be found.
+        CPIR                    ; search for code $00 - $17 skipping
+                                ; all ASCII text.
+;   At this point HL addresses first character of message.
+<a name="L02A7"></a>;; <b>PR-REP-LP</b>
+L02A7:  LD      A,(HL)          ; fetch each character in turn.
+        CP      $20             ; compare to space.
+        JR      C,<A href="#L02B4">L02B4</a>         ; forward if less to END-PR-MS
+        PUSH    HL              ; save the character pointer
+        RST     10H             ; CALBAS
+        DEFW    $0010           ; main PRINT-A
+        POP     HL              ; restore pointer
+        INC     HL              ; and increment.
+        JR      <A href="#L02A7">L02A7</a>           ; loop back to PR-REP-LP
+; ---
+<a name="L02B4"></a>;; <b>END-PR-MS</b>
+L02B4:  LD      SP,($5C3D)      ; set machine stack pointer from ERR_SP
+        INC     SP              ; prepare to overwrite the MAIN-4
+        INC     SP              ; address $1303.
+        LD      HL,$1349        ; substitute with the part that prints
+                                ; the comma and line statement.
+        PUSH    HL              ; push address to base of stack.
+        RST     00H             ; return to MAIN-ROM.
+;   <font color=#9900FF>Note.</font> at this stage we have, say, "Program finished" on the screen and
+;   the Main ROM routine at $1349 will complete the ", 0:1" part looping
+;   back to MAIN-2 to put $1303 on the stack again.
+; ------------------------------------
+; THE <b><font color=#333388>'SHADOW REPORT MESSAGES'</font></b> ROUTINE
+; ------------------------------------
+;   These are the Shadow Error Reports.  <font color=#9900FF>Note.</font> that the never used
+;   "Header mismatch error" has been largely reclaimed.  Each error code,
+;   which must be less than a space, serves to delimit the preceding text.
+;   The final delimiter might just as well be $18.
+<a name="L02BF"></a>;; <b>REP-MSGS</b>
+L02BF   DEFB    $00
+        DEFM    "Program finished"
+        DEFB    $01
+        DEFM    "Nonsense in BASIC"     ; Duplicate of a Main ROM error
+        DEFB    $02
+        DEFM    "Invalid stream number"
+        DEFB    $03
+        DEFM    "Invalid device expression"
+        DEFB    $04
+        DEFM    "Invalid name"
+        DEFB    $05
+        DEFM    "Invalid drive number"
+        DEFB    $06
+        DEFM    "Invalid station number"
+        DEFB    $07
+        DEFM    "Missing name"
+        DEFB    $08
+        DEFM    "Missing station number"
+        DEFB    $09
+        DEFM    "Missing drive number"
+        DEFB    $0A
+        DEFM    "Missing baud rate"
+        DEFB    $0B
+        DEFM    "er mismatch e"         ; <font color=#9900FF>Note.</font> remnants of unused text.
+        DEFB    $0C
+        DEFM    "Stream already open"
+        DEFB    $0D
+        DEFM    "Writing to a 'read' file"
+        DEFB    $0E
+        DEFM    "Reading a 'write' file"
+        DEFB    $0F
+        DEFM    "Drive 'write' protected"
+        DEFB    $10
+        DEFM    "Microdrive full"
+        DEFB    $11
+        DEFM    "Microdrive not present"
+        DEFB    $12
+        DEFM    "File not found"
+        DEFB    $13
+        DEFM    "Hook code error"       ; not listed in manual.
+        DEFB    $14
+        DEFM    "CODE error"
+        DEFB    $15
+        DEFM    "MERGE error"
+        DEFB    $16
+        DEFM    "Verification has failed"
+        DEFB    $17
+        DEFM    "Wrong file type"
+        DEFB    $18                     ; end-marker
+; *********************************************
+; **  T H E   S Y N T A X   R O U T I N E S  **
+; *********************************************
+; --------------------------------
+; THE <b><font color=#333388>'CAT COMMAND SYNTAX'</font></b> ROUTINE
+; --------------------------------
+;   e.g. CAT 3
+;   Without the syntax tables of the Main ROM, checking syntax is quite
+;   laborious.  Although the Main ROM allowed CAT without a parameter, a
+;   single expression in the range 1 - 8 is now required.  By default, CAT
+;   outputs to the upper screen but output may be directed to any stream in
+;   the range 0 to 15 decimal.  The subroutines used to evaluate the numeric
+;   expressions use the SCANNING routine, in Main ROM, which inserts the
+;   hidden five-byte numbers after any numeric arguments.
+<a name="L0486"></a>;; <b>CAT-SYN</b>
+L0486:  LD      HL,$5CD8        ; address system variable S_STR1.
+        LD      (HL),$02        ; default to stream 2 the screen.
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CP      $0D             ; carriage return ?
+        JR      Z,<A href="#L0494">L0494</a>         ; forward, if so, to MISSING-D
+        CP      $3A             ; is character ':' ?
+<a name="L0494"></a>;; <b>MISSING-D</b>
+L0494:  JP      Z,<A href="#L0683">L0683</a>         ; jump if no parameter to NREPORT-9
+        CP      $23             ; is character '#' ?
+        JR      NZ,<A href="#L04A6">L04A6</a>        ; forward to CAT-SCRN
+;   Output is directed at a specific stream.
+        CALL    <A href="#L064E">L064E</a>           ; routine EXPT-STRM checks for number in range.
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR checks for ',' or ';'.
+        JR      NZ,<A href="#L04B2">L04B2</a>        ; forward, if not present, to OREPORT-1
+                                ; 'Nonsense in BASIC'
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+<a name="L04A6"></a>;; <b>CAT-SCRN</b>
+L04A6:  CALL    <A href="#L061E">L061E</a>           ; routine EXPT-NUM
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        CALL    <A href="#L066D">L066D</a>           ; routine CHECK-M-2 checks that drive is in
+                                ; range 1 - 8.
+        JP      <A href="#L1AB5">L1AB5</a>           ; jump forward to CAT-RUN
+; ---
+<a name="L04B2"></a>;; <b>OREPORT-1</b>
+L04B2:  RST     20H             ; Shadow Error Restart
+        DEFB    $00             ; Nonsense in BASIC
+; -----------------------------------
+; THE <b><font color=#333388>'FORMAT COMMAND SYNTAX'</font></b> ROUTINE
+; -----------------------------------
+;   e.g.
+<a name="L04B4"></a>;; <b>FRMT-SYN</b>
+L04B4:  CALL    <A href="#L05F2">L05F2</a>           ; routine EXPT-SPEC
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR
+        JR      NZ,<A href="#L04BF">L04BF</a>        ; forward to NO-FOR-M
+        CALL    <A href="#L062F">L062F</a>           ; routine EXPT-NAME
+<a name="L04BF"></a>;; <b>NO-FOR-M</b>
+L04BF:  CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $54             ; is character  "T" ?
+        JR      Z,<A href="#L04CD">L04CD</a>         ; forward to FOR-B-T
+        CP      $42             ; is character  "B" ?
+        JR      NZ,<A href="#L04D3">L04D3</a>        ; forward to NOT-FOR-B
+<a name="L04CD"></a>;; <b>FOR-B-T</b>
+L04CD:  CALL    <A href="#L06B0">L06B0</a>           ; routine TEST-BAUD
+        JP      <A href="#L0ACD">L0ACD</a>           ; jump to SET-BAUD
+<a name="L04D3"></a>;; <b>NOT-FOR-B</b>
+L04D3:  CP      $4E             ; is character "N" ?
+        JR      NZ,<A href="#L04E7">L04E7</a>        ; forward to FOR-M
+        CALL    <A href="#L068F">L068F</a>           ; routine TEST-STAT
+        LD      A,($5CD6)       ; sv D_STR1 drive number
+        AND     A
+        JP      Z,<A href="#L069F">L069F</a>         ; jump to NREPORT-6
+        LD      ($5CC5),A       ; sv NTSTAT
+        JP      <A href="#L05C1">L05C1</a>           ; jump to END1
+<a name="L04E7"></a>;; <b>FOR-M</b>
+L04E7:  CALL    <A href="#L0685">L0685</a>           ; routine TEST-MNAM
+        JP      <A href="#L1ABA">L1ABA</a>           ; jump to FOR-RUN
+; ---------------------------------
+; THE <b><font color=#333388>'OPEN COMMAND SYNTAX'</font></b> ROUTINE
+; ---------------------------------
+;
+<a name="L04ED"></a>;; <b>OPEN-SYN</b>
+L04ED:  CALL    <A href="#L064E">L064E</a>           ; routine EXPT-STRM
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR
+        JR      NZ,<A href="#L04B2">L04B2</a>        ; back to OREPORT-1
+                                ; 'Nonsense in BASIC'
+        CALL    <A href="#L05F2">L05F2</a>           ; routine EXPT-SPEC
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR
+        JR      NZ,<A href="#L0500">L0500</a>        ; forward to NOT-OP-M
+        CALL    <A href="#L062F">L062F</a>           ; routine EXPT-NAME
+<a name="L0500"></a>;; <b>NOT-OP-M</b>
+L0500:  CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        LD      A,($5CD8)       ; sv D_STR1
+        RST     10H             ; CALBAS
+        DEFW    $1727           ; main STR-DATA1
+        LD      HL,$0011        ;
+        AND     A               ;
+        SBC     HL,BC           ;
+        JR      C,<A href="#L052F">L052F</a>         ; forward to NREPORT-C
+        LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $54             ; "T" ?
+        JR      Z,<A href="#L051C">L051C</a>         ; forward to OPEN-RS
+        CP      $42             ; "B" ?
+        JR      NZ,<A href="#L051F">L051F</a>        ; forward to NOT-OP-B
+<a name="L051C"></a>;; <b>OPEN-RS</b>
+L051C:  JP      <A href="#L0B4E">L0B4E</a>           ; jump to OP-RSCHAN
+; ---
+<a name="L051F"></a>;; <b>NOT-OP-B</b>
+L051F:  CP      $4E             ; is character "N" ?
+        JR      NZ,<A href="#L0529">L0529</a>        ; forward to OP-M-C
+        CALL    <A href="#L068F">L068F</a>           ; routine TEST-STAT
+        JP      <A href="#L0F40">L0F40</a>           ; jump to OPEN-N-ST
+; ---
+<a name="L0529"></a>;; <b>OP-M-C</b>
+L0529:  CALL    <A href="#L0685">L0685</a>           ; routine TEST-MNAM
+        JP      <A href="#L1ABF">L1ABF</a>           ; jump to OP-RUN
+; ---
+<a name="L052F"></a>;; <b>NREPORT-C</b>
+L052F:  RST     20H             ; Shadow Error Restart
+        DEFB    $0B             ; Stream already open
+; ----------------------------------
+; THE <b><font color=#333388>'ERASE COMMAND SYNTAX'</font></b> ROUTINE
+; ----------------------------------
+;
+<a name="L0531"></a>;; <b>ERASE-SYN</b>
+L0531:  CALL    <A href="#L06A3">L06A3</a>           ; routine EXPT-EXPR
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        CALL    <A href="#L0685">L0685</a>           ; routine TEST-MNAM
+        JP      <A href="#L1AAB">L1AAB</a>           ; jump to ERASE-RUN
+; ---------------------------------
+; THE <b><font color=#333388>'MOVE COMMAND SYNTAX'</font></b> ROUTINE
+; ---------------------------------
+;
+<a name="L053D"></a>;; <b>MOVE-SYN</b>
+L053D:  CALL    <A href="#L06B9">L06B9</a>           ; routine EXPT-EXP1
+        CALL    <A href="#L059F">L059F</a>           ; routine EX-D-STR
+        RST     10H             ; CALBAS
+        DEFW    $0018           ; main GET-CHAR
+        CP      $CC             ; 'TO' ?
+        JR      NZ,<A href="#L0584">L0584</a>        ; forward to NONSENSE
+        CALL    <A href="#L06B9">L06B9</a>           ; routine EXPT-EXP1
+        CALL    <A href="#L059F">L059F</a>           ; routine EX-D-STR
+        RST     10H             ; CALBAS
+        DEFW    $0018           ; main GET-CHAR
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        JP      <A href="#L1AB0">L1AB0</a>           ; jump to MOVE-RUN
+; --------------------------
+; THE <b><font color=#333388>'CLS# COMMAND'</font></b> ROUTINE
+; --------------------------
+;
+<a name="L0559"></a>;; <b>CLS#-SYN</b>
+L0559:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CP      $23             ; is the character '#' ?
+        JR      NZ,<A href="#L0584">L0584</a>        ; forward, if not, to NONSENSE
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        LD      HL,<A href="#L0038">L0038</a>        ; prepare a zero and black ink on white paper.
+        LD      ($5C8D),HL      ; set system variables ATTR_P and MASK_P.
+        LD      ($5C8F),HL      ; set system variables ATTR_T and MASK_T.
+                                ; <font color=#9900FF>Note.</font> not really necessary as done by CLS.
+        LD      (IY+$0E),L      ; set system variable BORDCR to colour scheme.
+        LD      (IY+$57),H      ; set system variable P_FLAG to zero.
+        LD      A,$07           ; load A with white.
+        OUT     ($FE),A         ; directly change border colour.
+        RST     10H             ; CALBAS
+        DEFW    $0D6B           ; main CLS clears screen and sets colours.
+        JP      <A href="#L05C1">L05C1</a>           ; jump forward to END1.
+; ----------------------------
+; THE <b><font color=#333388>'CLEAR# COMMAND'</font></b> ROUTINE
+; ----------------------------
+;
+<a name="L057F"></a>;; <b>CLR#-SYN</b>
+L057F:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CP      $23             ; '#' ?
+<a name="L0584"></a>;; <b>NONSENSE</b>
+L0584:  JP      NZ,<A href="#L04B2">L04B2</a>        ; jump to OREPORT-1
+                                ; 'Nonsense in BASIC'
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        XOR     A               ;
+<a name="L058E"></a>;; <b>ALL-STRMS</b>
+L058E:  PUSH    AF              ;
+        SET     1,(IY+$7C)      ; sv FLAGS_3
+        CALL    <A href="#L1718">L1718</a>           ; routine CLOSE
+        POP     AF              ;
+        INC     A               ;
+        CP      $10             ;
+        JR      C,<A href="#L058E">L058E</a>         ; back to ALL-STRMS
+        JP      <A href="#L05C1">L05C1</a>           ; jump to END1
+; -----------------------------------------------------
+; THE <b><font color=#333388>'EXCHANGE FILE SPECIFIERS DSTRI AND STR2'</font></b> ROUTINE
+; -----------------------------------------------------
+;   This routine is used by the MOVE routines to bring one of the two 8-byte
+;   file specifiers into context.  There were two similar routines in the
+;   first Interface 1 ROM and this, the most efficient, has survived.
+<a name="L059F"></a>;; <b>EX-D-STR</b>
+L059F:  LD      HL,$5CD6        ; sv D_STR1. drive number
+        LD      DE,$5CDE        ; sv D_STR2.
+        LD      B,$08           ; eight bytes to swap.
+<a name="L05A7"></a>;; <b>ALL-BYTES</b>
+L05A7:  LD      A,(DE)          ; fetch byte 1.
+        LD      C,(HL)          ; fetch byte 2.
+        LD      (HL),A          ; place byte 1.
+        LD      A,C             ; byte 2 to accumulator.
+        LD      (DE),A          ; place byte 2.
+        INC     HL              ; increment the
+        INC     DE              ; two pointers.
+        DJNZ    <A href="#L05A7">L05A7</a>           ; loop back, for all eight, to ALL-BYTES.
+        RET                     ; return.
+; -----------------------
+; THE <b><font color=#333388>'SEPARATOR'</font></b> ROUTINE
+; -----------------------
+;   This routine returns with zero flag set if the current character is
+;   either a comma or semi-colon.
+<a name="L05B1"></a>;; <b>SEPARATOR</b>
+L05B1:  CP      $2C             ; is character ',' ?
+        RET     Z               ; return with zero set if so.
+        CP      $3B             ; is character ';' ?
+        RET                     ; return.
+; ------------------------------
+; THE <b><font color=#333388>'END OF STATEMENT'</font></b> ROUTINE
+; ------------------------------
+;
+<a name="L05B7"></a>;; <b>ST-END</b>
+L05B7:  CP      $0D             ; is character carriage return ?
+        JR      Z,<A href="#L05BF">L05BF</a>         ; forward, if so, to TEST-RET
+        CP      $3A             ; is character a ':' ?
+        JR      NZ,<A href="#L0584">L0584</a>        ; back, if not, to NONSENSE
+<a name="L05BF"></a>;; <b>TEST-RET</b>
+L05BF:  RST     18H             ; checking syntax ?
+        RET     NZ              ; return if not.
+; --------------------------------------------
+; THE <b><font color=#333388>'RETURN TO THE MAIN INTERPRETER'</font></b> ROUTINE
+; --------------------------------------------
+;
+<a name="L05C1"></a>;; <b>END1</b>
+L05C1:  LD      SP,($5C3D)      ; sv ERR_SP
+        LD      (IY+$00),$FF    ; sv ERR_NR
+        LD      HL,$1BF4        ; Main ROM address STMT-NEXT
+        RST     18H             ; checking syntax ?
+        JR      Z,<A href="#L05E0">L05E0</a>         ; forward, if so, to RETAD-SYN
+        LD      A,$7F           ;
+        IN      A,($FE)         ;
+        RRA                     ;
+        JR      C,<A href="#L05DD">L05DD</a>         ; forward to RETAD-RUN
+        LD      A,$FE           ;
+        IN      A,($FE)         ;
+        RRA                     ;
+        JR      NC,<A href="#L05E2">L05E2</a>        ; forward to BREAK-PGM
+<a name="L05DD"></a>;; <b>RETAD-RUN</b>
+L05DD:  LD      HL,$1B7D        ; Main ROM address STMT-R-1
+<a name="L05E0"></a>;; <b>RETAD-SYN</b>
+L05E0:  PUSH    HL              ;
+        RST     00H             ; to MAIN-ROM
+; ---
+<a name="L05E2"></a>;; <b>BREAK-PGM</b>
+L05E2:  LD      (IY+$00),$14    ; insert error code in system variable ERR_NR.
+        RST     28H             ; Error Main ROM
+                                ; 'BREAK into program'
+; ----------------------------------------
+; THE <b><font color=#333388>'EVALUATE STRING EXPRESSION'</font></b> ROUTINE
+; ----------------------------------------
+;
+<a name="L05E7"></a>;; <b>EXPT-STR</b>
+L05E7:  RST     10H             ; CALBAS
+        DEFW    $1C8C           ; main EXPT-EXP
+        RST     18H             ; checking syntax ?
+        RET     Z
+        PUSH    AF
+        RST     10H             ; CALBAS
+        DEFW    $2BF1           ; main STK-FETCH
+        POP     AF
+        RET
+; -----------------------------------------
+; THE <b><font color=#333388>'EVALUATE CHANNEL EXPRESSION'</font></b> ROUTINE
+; -----------------------------------------
+;
+<a name="L05F2"></a>;; <b>EXPT-SPEC</b>
+L05F2:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+<a name="L05F5"></a>;; <b>EXP-SPEC2</b>
+L05F5   CALL    <A href="#L05E7">L05E7</a>           ; routine EXPT-STR evaluates a string e.g. "m"
+                                ; start in DE, length in BC.
+; one of the main tenets of Sinclair BASIC is that a value can be replaced
+; by an expression of the same type at any time, so this routine must allow
+; something like "tomato"(3) as well as the more conventional "m" specifier.
+; Only in runtime when the expression is evaluated can a single character be
+; insisted upon.
+        JR      Z,<A href="#L060C">L060C</a>         ; forward, if checking syntax, to TEST-NEXT.
+        PUSH    AF              ; save following character.
+        LD      A,C             ; in runtime check
+        DEC     A               ; immediately for
+        OR      B               ; a single character.
+        JR      NZ,<A href="#L062D">L062D</a>        ; forward, if not, to NREPORT-3
+                                ; 'Invalid device expression'
+        LD      A,(DE)          ; fetch the addressed character.
+        RST     10H             ; CALBAS
+        DEFW    $2C8D           ; main ALPHA
+        JR      NC,<A href="#L062D">L062D</a>        ; forward, if not alphabetic, to NREPORT-3
+        AND     $DF             ; convert to uppercase with 'AND %11011111'
+        LD      ($5CD9),A       ; place in system variable L_STR1 device letter.
+        POP     AF              ; restore the following character.
+<a name="L060C"></a>;; <b>TEST-NEXT</b>
+L060C:  CP      $0D             ; test for carriage return.
+        RET     Z               ; return if so.
+        CP      $3A             ; is character ':' ?
+        RET     Z               ; return if so.
+        CP      $A5             ; RND
+        RET     NC              ; return with a token??
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR tests for both ';' and ','.
+        JP      NZ,<A href="#L04B2">L04B2</a>        ; jump back, if not, to OREPORT-1
+                                ; 'Nonsense in BASIC'
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+; -----------------------------------------------
+; THE <b><font color=#333388>'EVALUATE NUMERIC DRIVE EXPRESSION'</font></b> ROUTINE
+; -----------------------------------------------
+;   This routine is called once only to evaluate the numeric expression
+;   following a 'CAT' command token or is used from above to check a numeric
+;   expression following for example "M"; .
+<a name="L061E"></a>;; <b>EXPT-NUM</b>
+L061E:  RST     10H             ; CALBAS
+        DEFW    $1C82           ; main EXPT-1NUM
+        RST     18H             ; checking syntax ?
+        RET     Z               ; return if checking syntax.
+        PUSH    AF              ; save NZ not syntax flag
+        RST     10H             ; CALBAS
+        DEFW    $1E99           ; main FIND-INT2
+        LD      ($5CD6),BC      ; set system variable D_STR1 drive number
+        POP     AF              ; restore NZ not syntax flag
+        RET                     ; return.
+; ---
+<a name="L062D"></a>;; <b>NREPORT-3</b>
+L062D:  RST     20H             ; Shadow Error Restart
+        DEFB    $02             ; 'Invalid device expression'
+; -------------------------------
+; THE <b><font color=#333388>'EVALUATE FILENAME'</font></b> ROUTINE
+; -------------------------------
+;
+<a name="L062F"></a>;; <b>EXPT-NAME</b>
+L062F:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CALL    <A href="#L05E7">L05E7</a>           ; routine EXPT-STR
+        RET     Z
+        PUSH    AF
+        LD      A,C
+        OR      B
+        JR      Z,<A href="#L064C">L064C</a>         ; forward to NREPORT-4
+        LD      HL,$000A
+        SBC     HL,BC
+        JR      C,<A href="#L064C">L064C</a>         ; forward to NREPORT-4
+        LD      ($5CDA),BC      ; sv N_STR1
+        LD      ($5CDC),DE      ; sv D_STR1
+        POP     AF
+        RET
+; ---
+<a name="L064C"></a>;; <b>NREPORT-4</b>
+L064C:  RST     20H             ; Shadow Error Restart
+        DEFB    $03             ; Invalid name
+; ------------------------------------
+; THE <b><font color=#333388>'EVALUATE STREAM NUMBER'</font></b> ROUTINE
+; ------------------------------------
+;
+<a name="L064E"></a>;; <b>EXPT-STRM</b>
+L064E:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        RST     10H             ; CALBAS
+        DEFW    $1C82           ; main EXPT-1NUM
+        RST     18H             ; checking syntax ?
+        RET     Z               ;
+        PUSH    AF              ;
+        RST     10H             ; CALBAS
+        DEFW    $1E94           ; main FIND-INT1
+        CP      $10             ;
+        JR      NC,<A href="#L0663">L0663</a>        ; forward to NREPORT-2
+        LD      ($5CD8),A       ; sv D_STR1
+        POP     AF              ;
+        RET                     ;
+; ---
+<a name="L0663"></a>;; <b>NREPORT-2</b>
+L0663:  RST     20H             ; Shadow Error Restart
+        DEFB    $01             ; Invalid stream number
+; ----------------------------------
+; THE <b><font color=#333388>'CHECK "M" PARAMETERS'</font></b> ROUTINE
+; ----------------------------------
+; called once from TEST-MNAM
+<a name="L0665"></a>;; <b>CHECK-M</b>
+L0665:  LD      A,($5CD9)       ; fetch system variable L_STR1 device letter.
+        CP      $4D             ; is character "M" ?
+        JP      NZ,<A href="#L062D">L062D</a>        ; jump back, if not, to NREPORT-3
+                                ; Error: 'Invalid device expression'.
+<a name="L066D"></a>;; <b>CHECK-M-2</b>
+L066D:  LD      DE,($5CD6)      ; fetch system variable D_STR1 drive number.
+        LD      A,E             ; test for
+        OR      D               ; zero.
+        JR      Z,<A href="#L0681">L0681</a>         ; forward, if so, to NREPORT-5
+                                ; 'Invalid drive number'
+        INC     DE              ; also test that
+        LD      A,E             ; location does not hold
+        OR      D               ; the default $FFFF value.
+        JR      Z,<A href="#L0683">L0683</a>         ; forward, if so, to NREPORT-9
+                                ; 'Missing drive number'.
+        DEC     DE              ; restore to initial value.
+        LD      HL,<A href="#L0008">L0008</a>        ; and test that
+        SBC     HL,DE           ; drive is in range 1 - 8.
+        RET     NC              ; return if so.
+<a name="L0681"></a>;; <b>NREPORT-5</b>
+L0681:  RST     20H             ; Shadow Error Restart
+        DEFB    $04             ; Invalid drive number
+; ---
+<a name="L0683"></a>;; <b>NREPORT-9</b>
+L0683:  RST     20H             ; Shadow Error Restart
+        DEFB    $08             ; Missing drive number
+; -----------------------------------------------
+; THE <b><font color=#333388>'CHECK "M" PARAMETERS AND FILENAME'</font></b> ROUTINE
+; -----------------------------------------------
+; This routine checks that the device expression is "M", that the drive is in
+; the range 1 - 8 and that the filename is not null.
+<a name="L0685"></a>;; <b>TEST-MNAM</b>
+L0685:  CALL    <A href="#L0665">L0665</a>           ; routine CHECK-M checks for "M" and valid
+                                ; drive number.
+        LD      A,($5CDB)       ; load A with D_STR1 the high byte of length
+                                ; of filename.
+        AND     A               ; test for zero.
+        RET     Z               ; return if so.
+; else system default $FF.
+        RST     20H             ; Shadow Error Restart
+        DEFB    $06             ; Missing name
+; ----------------------------------
+; THE <b><font color=#333388>'CHECK STATION NUMBER'</font></b> ROUTINE
+; ----------------------------------
+;
+<a name="L068F"></a>;; <b>TEST-STAT</b>
+L068F:  LD      DE,($5CD6)      ; sv D_STR1 drive number
+        INC     DE
+        LD      A,E
+        OR      D
+        JR      Z,<A href="#L06A1">L06A1</a>         ; forward to NREPORT-8
+        DEC     DE
+        LD      HL,L0040
+        SBC     HL,DE
+        RET     NC
+<a name="L069F"></a>;; <b>NREPORT-6</b>
+L069F:  RST     20H             ; Shadow Error Restart
+        DEFB    $05             ; Invalid station number
+<a name="L06A1"></a>;; <b>NREPORT-8</b>
+L06A1:  RST     20H             ; Shadow Error Restart
+        DEFB    $07             ; Missing station number
+; -----------------------------------
+; THE <b><font color=#333388>'EVALUATE "X";N;"NAME"'</font></b> ROUTINE
+; -----------------------------------
+;
+<a name="L06A3"></a>;; <b>EXPT-EXPR</b>
+L06A3:  CALL    <A href="#L05F2">L05F2</a>           ; routine EXPT-SPEC
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR
+        JP      NZ,<A href="#L04B2">L04B2</a>        ; jump to OREPORT-1
+                                ; 'Nonsense in BASIC'
+        CALL    <A href="#L062F">L062F</a>           ; routine EXPT-NAME
+        RET                     ; return...
+; -----------------------------
+; THE <b><font color=#333388>'CHECK BAUD RATE'</font></b> ROUTINE
+; -----------------------------
+;
+<a name="L06B0"></a>;; <b>TEST-BAUD</b>
+L06B0:  LD      HL,($5CD6)      ; sv D_STR1 drive number
+        INC     HL
+        LD      A,L
+        OR      H
+        RET     NZ
+        RST     20H             ; Shadow Error Restart
+        DEFB    $09             ; Missing baud rate
+; -------------------------------------------
+; THE <b><font color=#333388>'EVALUATE STREAM OR EXPRESSION'</font></b> ROUTINE
+; -------------------------------------------
+;
+<a name="L06B9"></a>;; <b>EXPT-EXP1</b>
+L06B9:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CP      $23             ; is character '#' ?
+        JP      Z,<A href="#L064E">L064E</a>         ; jump to EXPT-STRM
+        CALL    <A href="#L05F5">L05F5</a>           ; routine EXP-SPEC2
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR
+        JR      NZ,<A href="#L06CC">L06CC</a>        ; forward to ENDHERE
+        CALL    <A href="#L062F">L062F</a>           ; routine EXPT-NAME
+<a name="L06CC"></a>;; <b>ENDHERE</b>
+L06CC:  RST     18H             ; checking syntax ?
+        RET     Z
+        LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $54             ; is character "T" ?
+        RET     Z               ;
+        CP      $42             ; is character "B" ?
+        RET     Z               ;
+        CP      $4E             ; is character "N" ?
+        JP      Z,<A href="#L068F">L068F</a>         ; jump, if so, to TEST-STAT
+        JP      <A href="#L0685">L0685</a>           ; jump to TEST-MNAM
+; ---
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+; --------------------
+; THE <b><font color=#333388>'UNPAGE'</font></b> ROUTINE
+; --------------------
+;
+<a name="L0700"></a>;; <b>UNPAGE</b>
+L0700:  RET
+; ---------------------------------
+; THE <b><font color=#333388>'EVALUATE PARAMETERS'</font></b> ROUTINE
+; ---------------------------------
+;
+<a name="L0701"></a>;; <b>EXPT-PRMS</b>
+L0701:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CP      $2A             ; is character '*'
+        JR      NZ,<A href="#L073C">L073C</a>        ; forward, if not, to OREP-1-2
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CALL    <A href="#L05F5">L05F5</a>           ; routine EXP-SPEC2
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR
+        JR      NZ,<A href="#L0716">L0716</a>        ; forward to NO-NAME
+        CALL    <A href="#L062F">L062F</a>           ; routine EXPT-NAME
+<a name="L0716"></a>;; <b>NO-NAME</b>
+L0716:  PUSH    AF
+        LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $4E             ; is character "N" ?
+        JR      NZ,<A href="#L0722">L0722</a>        ; forward, if not, to NOT-NET
+        SET     3,(IY+$7C)      ; update FLAGS_3 signal networking.
+<a name="L0722"></a>;; <b>NOT-NET</b>
+L0722:  POP     AF
+        CP      $0D             ; is character carriage return ?
+        JR      Z,<A href="#L0750">L0750</a>         ; forward to END-EXPT
+        CP      $3A             ; is character ':' ?
+        JR      Z,<A href="#L0750">L0750</a>         ; forward to END-EXPT
+        CP      $AA             ; is character the token 'SCREEN$' ?
+        JR      Z,<A href="#L0771">L0771</a>         ; forward to SCREEN$
+        CP      $AF             ; is character the token 'CODE' ?
+        JR      Z,<A href="#L0789">L0789</a>         ; forward to CODE
+        CP      $CA             ; is character the token 'LINE' ?
+        JR      Z,<A href="#L073E">L073E</a>         ; forward to LINE
+        CP      $E4             ; is character the token 'DATA' ?
+        JP      Z,<A href="#L07D2">L07D2</a>         ; jump to DATA
+<a name="L073C"></a>;; <b>OREP-1-2</b>
+L073C:  RST     20H             ; Shadow Error Restart
+        DEFB    $00             ; Nonsense in BASIC
+; ---
+<a name="L073E"></a>;; <b>LINE</b>
+L073E:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        RST     10H             ; CALBAS
+        DEFW    $1C82           ; main EXPT-1NUM
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        RST     10H             ; CALBAS
+        DEFW    $1E99           ; main FIND-INT2
+        LD      ($5CED),BC      ; sv HD_11
+        JR      <A href="#L0753">L0753</a>           ; forward to PROG
+; ---
+<a name="L0750"></a>;; <b>END-EXPT</b>
+L0750:  CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+; the 'PROGRAM' SUBROUTINE is used when loading 'run'.
+<a name="L0753"></a>;; <b>PROG</b>
+L0753:  XOR     A               ;
+        LD      ($5CE6),A       ; sv HD_00
+        LD      HL,($5C59)      ; sv E_LINE
+        LD      DE,($5C53)      ; sv PROG
+        LD      ($5CE9),DE      ; sv HD_0D
+        SCF                     ;
+        SBC     HL,DE           ;
+        LD      ($5CE7),HL      ; sv HD_0B
+        LD      HL,($5C4B)      ; sv VARS
+        SBC     HL,DE           ;
+        LD      ($5CEB),HL      ; sv HD_0F
+        RET
+; ---
+<a name="L0771"></a>;; <b>SCREEN$</b>
+L0771:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        LD      HL,$1B00
+        LD      ($5CE7),HL      ; sv HD_0B
+        LD      HL,$4000
+        LD      ($5CE9),HL      ; sv HD_0D
+        LD      A,$03
+        LD      ($5CE6),A       ; sv HD_00
+        RET
+; ---
+<a name="L0789"></a>;; <b>CODE</b>
+L0789:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CP      $0D             ; is character a carriage return ?
+        JR      Z,<A href="#L079A">L079A</a>         ; forward to DEFLT-0
+        CP      $3A             ; is character a ':' ?
+        JR      NZ,<A href="#L079F">L079F</a>        ; forward to PAR-1
+        BIT     5,(IY+$7C)      ; sv FLAGS_3
+        JR      NZ,<A href="#L073C">L073C</a>        ; back to OREP-1-2
+<a name="L079A"></a>;; <b>DEFLT-0</b>
+L079A:  RST     10H             ; CALBAS
+        DEFW    $1CE6           ; main USE-ZERO
+        JR      <A href="#L07A7">L07A7</a>           ; forward to TEST-SAVE
+; ---
+<a name="L079F"></a>;; <b>PAR-1</b>
+L079F:  RST     10H             ; CALBAS
+        DEFW    $1C82           ; main EXPT-1NUM
+        CALL    <A href="#L05B1">L05B1</a>           ; routine SEPARATOR
+        JR      Z,<A href="#L07B2">L07B2</a>         ; forward to PAR-2
+<a name="L07A7"></a>;; <b>TEST-SAVE</b>
+L07A7:  BIT     5,(IY+$7C)      ; sv FLAGS_3
+        JR      NZ,<A href="#L073C">L073C</a>        ; back to OREP-1-2
+        RST     10H             ; CALBAS
+        DEFW    $1CE6           ; main USE-ZERO
+        JR      <A href="#L07B8">L07B8</a>           ; forward to END-CODE
+; ---
+<a name="L07B2"></a>;; <b>PAR-2</b>
+L07B2:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        RST     10H             ; CALBAS
+        DEFW    $1C82           ; main EXPT-1NUM
+<a name="L07B8"></a>;; <b>END-CODE</b>
+L07B8:  RST     10H             ; CALBAS
+        DEFW    $0018           ; main GET-CHAR
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        RST     10H             ; CALBAS
+        DEFW    $1E99           ; main FIND-INT2
+        LD      ($5CE7),BC      ; sv HD_0B
+        RST     10H             ; CALBAS
+        DEFW    $1E99           ; main FIND-INT2
+        LD      ($5CE9),BC      ; sv HD_0D
+        LD      A,$03
+        LD      ($5CE6),A       ; sv HD_00
+        RET                     ; return.
+; ---
+;
+; ---
+<a name="L07D2"></a>;; <b>DATA</b>
+L07D2:  BIT     6,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L07DA">L07DA</a>         ; forward to NO-M-ARR
+        RST     20H             ; Shadow Error Restart
+        DEFB    $14             ; MERGE error
+<a name="L07DA"></a>;; <b>NO-M-ARR</b>
+L07DA:  RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        RST     10H             ; CALBAS
+        DEFW    $28B2           ; main LOOK-VARS
+        SET     7,C
+        JR      NC,<A href="#L07F2">L07F2</a>        ; forward to EXISTING
+        LD      HL,$0000
+        BIT     4,(IY+$7C)      ; sv FLAGS_3
+        JR      NZ,<A href="#L080E">L080E</a>        ; forward to LD-DATA
+        LD      (IY+$00),$01    ; sv ERR_NR to '2 Variable not found'
+        RST     28H             ; Error Main ROM
+; ---
+<a name="L07F2"></a>;; <b>EXISTING</b>
+L07F2:  JR      Z,<A href="#L07F6">L07F6</a>         ; forward to G-TYPE
+<a name="L07F4"></a>;; <b>NONS-BSC</b>
+L07F4:  RST     20H             ; Shadow Error Restart
+        DEFB    $00             ; Nonsense in BASIC
+; ---
+<a name="L07F6"></a>;; <b>G-TYPE</b>
+L07F6:  RST     18H             ; checking syntax ?
+        JR      Z,<A href="#L081C">L081C</a>         ; forward to END-DATA
+        BIT     5,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L0803">L0803</a>         ; forward to VR-DATA
+        BIT     7,(HL)
+        JR      Z,<A href="#L07F4">L07F4</a>         ; back to NONS-BSC
+<a name="L0803"></a>;; <b>VR-DATA</b>
+L0803:  INC     HL
+        LD      A,(HL)
+        LD      ($5CE7),A       ; sv HD_0B
+        INC     HL
+        LD      A,(HL)
+        LD      ($5CE8),A       ; sv HD_0B_hi
+        INC     HL
+<a name="L080E"></a>;; <b>LD-DATA</b>
+L080E:  LD      A,C
+        LD      ($5CEB),A       ; sv HD_0F
+        LD      A,$01
+        BIT     6,C
+        JR      Z,<A href="#L0819">L0819</a>         ; forward to NUM-ARR
+        INC     A
+<a name="L0819"></a>;; <b>NUM-ARR</b>
+L0819:  LD      ($5CE6),A       ; sv HD_00
+<a name="L081C"></a>;; <b>END-DATA</b>
+L081C:  EX      DE,HL
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CP      $29             ; is character ')' ?
+        JR      NZ,<A href="#L07F4">L07F4</a>        ; back to NONS-BSC
+        RST     10H             ; CALBAS
+        DEFW    $0020           ; main NEXT-CHAR
+        CALL    <A href="#L05B7">L05B7</a>           ; routine ST-END
+        LD      ($5CE9),DE      ; sv HD_0D
+        RET                     ; return.
+; ---------------------------------
+; THE <b><font color=#333388>'SAVE COMMAND SYNTAX'</font></b> ROUTINE
+; ---------------------------------
+;
+<a name="L082F"></a>;; <b>SAVE-SYN</b>
+L082F:  SET     5,(IY+$7C)      ; sv FLAGS_3
+        CALL    <A href="#L0701">L0701</a>           ; routine EXPT-PRMS
+        LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $42             ; is character 'B' ?
+        JR      Z,<A href="#L084F">L084F</a>         ; forward to SA-HEADER
+        CP      $4E             ; is character 'N' ?
+        JR      NZ,<A href="#L0849">L0849</a>        ; forward to SAVE-M
+        CALL    <A href="#L068F">L068F</a>           ; routine TEST-STAT
+        CALL    <A href="#L0F46">L0F46</a>           ; routine OP-TEMP-N
+        JR      <A href="#L084F">L084F</a>           ; forward to SA-HEADER
+; ---
+<a name="L0849"></a>;; <b>SAVE-M</b>
+L0849:  CALL    <A href="#L0685">L0685</a>           ; routine TEST-MNAM
+        JP      <A href="#L1AC4">L1AC4</a>           ; jump to SAVE-RUN
+; ---
+<a name="L084F"></a>;; <b>SA-HEADER</b>
+L084F:  LD      B,$09
+        LD      HL,$5CE6        ; sv HD_00
+<a name="L0854"></a>;; <b>HD-LOOP</b>
+L0854:  CALL    <A href="#L0884">L0884</a>           ; routine SA-BYTE
+        INC     HL
+        DJNZ    <A href="#L0854">L0854</a>           ; back to HD-LOOP
+        LD      HL,($5CE9)      ; sv HD_0D
+        BIT     3,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L086E">L086E</a>         ; forward to SA-BLOCK
+        LD      A,($5CE6)       ; sv HD_00
+        CP      $03             ; compare with three - type CODE
+        JR      NC,<A href="#L086E">L086E</a>        ; forward to SA-BLOCK
+        LD      DE,$0114        ;
+        ADD     HL,DE           ;
+<a name="L086E"></a>;; <b>SA-BLOCK</b>
+L086E:  LD      BC,($5CE7)      ; sv HD_0B
+<a name="L0872"></a>;; <b>SA-BLK-LP</b>
+L0872:  LD      A,C             ;
+        OR      B               ;
+        JR      Z,<A href="#L0881">L0881</a>         ; forward to S-BLK-END
+        PUSH    IX              ;;;
+        CALL    <A href="#L0884">L0884</a>           ; routine SA-BYTE
+        POP     IX              ;;;
+        DEC     BC              ;
+        INC     HL              ;
+        JR      <A href="#L0872">L0872</a>           ; back to SA-BLK-LP
+; ---
+<a name="L0881"></a>;; <b>S-BLK-END</b>
+L0881:  JP      <A href="#L098C">L098C</a>           ; jump to TST-MR-M
+; --------------------------------------------------
+; THE <b><font color=#333388>'SAVE A BYTE TO NETWORK OR RS232 LINK'</font></b> ROUTINE
+; --------------------------------------------------
+;
+<a name="L0884"></a>;; <b>SA-BYTE</b>
+L0884:  PUSH    HL              ;
+        PUSH    BC              ;
+        BIT     3,(IY+$7C)      ; sv FLAGS_3
+        LD      A,(HL)          ;
+        JR      NZ,<A href="#L0892">L0892</a>        ; forward to SA-NET
+        CALL    <A href="#L0D07">L0D07</a>           ; routine BCHAN-OUT
+        JR      <A href="#L0895">L0895</a>           ; forward to SA-B-END
+; ---
+<a name="L0892"></a>;; <b>SA-NET</b>
+L0892:  CALL    <A href="#L0E09">L0E09</a>           ; routine NCHAN-OUT
+<a name="L0895"></a>;; <b>SA-B-END</b>
+L0895:  POP     BC              ;
+        POP     HL              ;
+        RET                     ;
+; ---------------------------------
+; THE <b><font color=#333388>'LOAD COMMAND SYNTAX'</font></b> ROUTINE
+; ---------------------------------
+;
+<a name="L0898"></a>;; <b>LOAD-SYN</b>
+L0898:  SET     4,(IY+$7C)      ; sv FLAGS_3
+        CALL    <A href="#L0701">L0701</a>           ; routine EXPT-PRMS
+        JP      <A href="#L08B3">L08B3</a>           ; jump to LD-VF-MR
+; -----------------------------------
+; THE <b><font color=#333388>'VERIFY COMMAND SYNTAX'</font></b> ROUTINE
+; -----------------------------------
+;
+<a name="L08A2"></a>;; <b>VERIF-SYN</b>
+L08A2:  SET     7,(IY+$7C)      ; sv FLAGS_3
+        CALL    <A href="#L0701">L0701</a>           ; routine EXPT-PRMS
+        JP      <A href="#L08B3">L08B3</a>           ; jump to LD-VF-MR
+; ----------------------------------
+; THE <b><font color=#333388>'MERGE COMMAND SYNTAX'</font></b> ROUTINE
+; ----------------------------------
+;
+<a name="L08AC"></a>;; <b>MRG-SYN</b>
+L08AC:  SET     6,(IY+$7C)      ; sv FLAGS_3
+        CALL    <A href="#L0701">L0701</a>           ; routine EXPT-PRMS
+; ----------------------------------------
+; THE <b><font color=#333388>'LOAD-VERIFY-MERGE COMMANDS'</font></b> ROUTINE
+; ----------------------------------------
+;
+<a name="L08B3"></a>;; <b>LD-VF-MR</b>
+L08B3:  LD      HL,$5CE6        ; set source to HD_00
+        LD      DE,$5CDE        ; set destination to D_STR2
+        LD      BC,$0007        ; seven bytes to copy.
+        LDIR                    ; copy type, start, length, length of program.
+        LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $4E             ; "N" ?
+        JR      Z,<A href="#L08D1">L08D1</a>         ; forward to TS-L-NET
+        CP      $42             ; "B" ?
+        JR      Z,<A href="#L08D7">L08D7</a>         ; forward to TS-L-RS
+; proceed with Microdrive device.
+        CALL    <A href="#L0685">L0685</a>           ; routine TEST-MNAM return without error if
+                                ; device is "M" and drive and filename are OK.
+        CALL    <A href="#L1971">L1971</a>           ; routine F-M-HEAD loads the header type
+                                ; record for the above filename and populates
+                                ; the locations HD_00 to HD_11.
+        JR      <A href="#L08F6">L08F6</a>           ; forward to TEST-TYPE which tests that file
+                                ; types agree and then loads rest of records.
+; ---
+<a name="L08D1"></a>;; <b>TS-L-NET</b>
+L08D1:  CALL    <A href="#L068F">L068F</a>           ; routine TEST-STAT
+        CALL    <A href="#L0F46">L0F46</a>           ; routine OP-TEMP-N
+<a name="L08D7"></a>;; <b>TS-L-RS</b>
+L08D7:  LD      HL,$5CE6        ; sv HD_00
+        LD      B,$09           ;
+<a name="L08DC"></a>;; <b>LD-HEADER</b>
+L08DC:  PUSH    HL
+        PUSH    BC
+        BIT     3,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L08EB">L08EB</a>         ; forward to LD-HD-RS
+<a name="L08E4"></a>;; <b>LD-HD-NET</b>
+L08E4:  CALL    <A href="#L0DAF">L0DAF</a>           ; routine NCHAN-IN
+        JR      NC,<A href="#L08E4">L08E4</a>        ; back to LD-HD-NET
+        JR      <A href="#L08F0">L08F0</a>           ; forward to LD-HDR-2
+; ---
+<a name="L08EB"></a>;; <b>LD-HD-RS</b>
+L08EB:  CALL    <A href="#L0B88">L0B88</a>           ; routine BCHAN-IN
+        JR      NC,<A href="#L08EB">L08EB</a>        ; back to LD-HD-RS
+<a name="L08F0"></a>;; <b>LD-HDR-2</b>
+L08F0:  POP     BC
+        POP     HL
+        LD      (HL),A
+        INC     HL
+        DJNZ    <A href="#L08DC">L08DC</a>           ; back to LD-HEADER
+; --&gt;
+<a name="L08F6"></a>;; <b>TEST-TYPE</b>
+L08F6:  LD      A,($5CDE)       ; sv D_STR2
+        LD      B,A
+        LD      A,($5CE6)       ; sv HD_00
+        CP      B
+        JR      NZ,<A href="#L0906">L0906</a>        ; forward to NREPORT-N
+        CP      $03             ; compare with three - type CODE
+        JR      Z,<A href="#L0915">L0915</a>         ; forward to T-M-CODE
+        JR      C,<A href="#L0908">L0908</a>         ; forward to TST-MERGE
+<a name="L0906"></a>;; <b>NREPORT-N</b>
+L0906:  RST     20H             ; Shadow Error Restart
+        DEFB    $16             ; Wrong file type
+; ---
+<a name="L0908"></a>;; <b>TST-MERGE</b>
+L0908:  BIT     6,(IY+$7C)      ; sv FLAGS_3
+        JR      NZ,<A href="#L096B">L096B</a>        ; forward to MERGE-BLK
+        BIT     7,(IY+$7C)      ; sv FLAGS_3
+        JP      Z,<A href="#L09A7">L09A7</a>         ; jump to LD-PR-AR
+<a name="L0915"></a>;; <b>T-M-CODE</b>
+L0915:  BIT     6,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L091D">L091D</a>         ; forward to LD-BLOCK
+        RST     20H             ; Shadow Error Restart
+        DEFB    $14             ; MERGE error
+; ---
+<a name="L091D"></a>;; <b>LD-BLOCK</b>
+L091D:  LD      HL,($5CDF)      ; sv D_STR2 (+1) length of data
+        LD      DE,($5CE7)      ; sv HD_0B
+        LD      A,H             ;
+        OR      L               ;
+        JR      Z,<A href="#L0936">L0936</a>         ; forward to LD-BLK-2
+        SBC     HL,DE           ;
+        JR      NC,<A href="#L0936">L0936</a>        ; forward to LD-BLK-2
+        BIT     4,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L0934">L0934</a>         ; forward to NREPORT-L
+        RST     20H             ; Shadow Error Restart
+        DEFB    $13             ; Code Error
+; ---
+<a name="L0934"></a>;; <b>NREPORT-L</b>
+L0934:  RST     20H             ; Shadow Error Restart
+        DEFB    $15             ; Verification has failed
+; ---
+<a name="L0936"></a>;; <b>LD-BLK-2</b>
+L0936:  LD      HL,($5CE1)      ; sv L_STR2
+        LD      A,(IX+$04)      ; channel letter
+        CP      $CD             ; 'M' +$80 ?
+        JR      NZ,<A href="#L0945">L0945</a>        ; forward to LD-BLK-3
+        LD      HL,($5CE4)      ; sv D_STR2             ********
+        JR      <A href="#L0956">L0956</a>           ; forward to LD-BLK-4
+; ---
+<a name="L0945"></a>;; <b>LD-BLK-3</b>
+L0945:  BIT     3,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L0956">L0956</a>         ; forward to LD-BLK-4
+        LD      A,($5CE6)       ; sv HD_00
+        CP      $03             ; compare with three - type CODE
+        JR      Z,<A href="#L0956">L0956</a>         ; forward to LD-BLK-4
+        LD      BC,$0114        ;
+        ADD     HL,BC           ;
+<a name="L0956"></a>;; <b>LD-BLK-4</b>
+L0956:  LD      A,H             ;
+        OR      L               ;
+        JR      NZ,<A href="#L095D">L095D</a>        ; forward to LD-BLK-5
+        LD      HL,($5CE9)      ; sv HD_0D
+<a name="L095D"></a>;; <b>LD-BLK-5</b>
+L095D:  LD      A,($5CE6)       ; sv HD_00
+        AND     A               ;
+        JR      NZ,<A href="#L0966">L0966</a>        ; forward to LD-NO-PGM
+        LD      HL,($5C53)      ; sv PROG
+<a name="L0966"></a>;; <b>LD-NO-PGM</b>
+L0966:  CALL    <A href="#L0A60">L0A60</a>           ; routine LV-ANY
+        JR      <A href="#L098C">L098C</a>           ; forward to TST-MR-M
+; ---
+<a name="L096B"></a>;; <b>MERGE-BLK</b>
+L096B:  LD      A,($5CEE)       ; sv HD_11_hi
+        AND     $C0             ;
+        JR      NZ,<A href="#L0977">L0977</a>        ; forward to NO-AUTOST
+        CALL    <A href="#L17B7">L17B7</a>           ; routine RCL-T-CH
+        RST     20H             ; Shadow Error Restart
+        DEFB    $14             ; MERGE error
+; ---
+<a name="L0977"></a>;; <b>NO-AUTOST</b>
+L0977:  LD      BC,($5CE7)      ; sv HD_0B
+        PUSH    BC              ;
+        INC     BC              ;
+        RST     10H             ; CALBAS
+        DEFW    $0030           ; main BC-SPACES
+        LD      (HL),$80        ;
+        EX      DE,HL           ;
+        POP     DE              ;
+        PUSH    HL              ;
+        CALL    <A href="#L0A60">L0A60</a>           ; routine LV-ANY
+        POP     HL              ;
+        RST     10H             ; CALBAS
+        DEFW    $08CE           ; main ME-CTRLX
+; ---
+<a name="L098C"></a>;; <b>TST-MR-M</b>
+L098C:  LD      A,(IX+$04)      ; channel letter
+        CP      $CD             ; 'M' + $80 ?
+        JR      NZ,<A href="#L0998">L0998</a>        ; forward to TST-MR-N
+        CALL    <A href="#L138E">L138E</a>           ; routine CLOSE-M2
+        JR      <A href="#L09A4">L09A4</a>           ; forward to MERGE-END
+; ---
+<a name="L0998"></a>;; <b>TST-MR-N</b>
+L0998:  BIT     3,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L09A4">L09A4</a>         ; forward to MERGE-END
+        CALL    <A href="#L0FAE">L0FAE</a>           ; routine SEND-NEOF
+        CALL    <A href="#L17B7">L17B7</a>           ; routine RCL-T-CH
+<a name="L09A4"></a>;; <b>MERGE-END</b>
+L09A4:  JP      <A href="#L05C1">L05C1</a>           ; jump to END1
+; ---
+<a name="L09A7"></a>;; <b>LD-PR-AR</b>
+L09A7:  LD      DE,($5CE7)      ; sv HD_0B
+        LD      HL,($5CE1)      ; sv L_STR2
+        PUSH    HL              ;
+        LD      A,H             ;
+        OR      L               ;
+        JR      NZ,<A href="#L09B9">L09B9</a>        ; forward to LD-PROG
+        INC     DE              ;
+        INC     DE              ;
+        INC     DE              ;
+        EX      DE,HL           ;
+        JR      <A href="#L09C2">L09C2</a>           ; forward to TST-SPACE
+; ---
+<a name="L09B9"></a>;; <b>LD-PROG</b>
+L09B9:  LD      HL,($5CDF)      ; sv D_STR2 (+1) length of data
+        EX      DE,HL           ;
+        SCF                     ;
+        SBC     HL,DE           ;
+        JR      C,<A href="#L09CB">L09CB</a>         ; forward to TST-TYPE
+<a name="L09C2"></a>;; <b>TST-SPACE</b>
+L09C2:  LD      DE,$0005        ;
+        ADD     HL,DE           ;
+        LD      B,H             ;
+        LD      C,L             ;
+        RST     10H             ; CALBAS
+        DEFW    $1F05           ; main TEST-ROOM
+;   <font color=#9900FF>Note.</font> that before the above call, interrupts are disabled and the motor
+;   of the microdrive is running.  If there should be insufficient room,
+;   then the processor stops at the HALT instruction at address $1303
+;   (MAIN-4), in the main ROM, while trying to output the "Out of Memory"
+;   report.  This could be corrected by replacing the above 3 bytes to a
+;   call to a 6-byte subroutine which carries out the same instructions
+;   between an EI/DI pair.  In the production of the "Out of Memory" report
+;   this ROM will be paged again by the instruction fetch at 0008. The
+;   motors are stopped at START-4 and then Control will then pass to the
+;   other ROM to execute the "LD A,(HL)", then back to this ROM to eliminate
+;   the "OK" message before a final switch to the Main ROM for the actual
+;   message text.
+<a name="L09CB"></a>;; <b>TST-TYPE</b>
+L09CB:  POP     HL
+        LD      A,($5CE6)       ; sv HD_00
+        AND     A
+        JR      Z,<A href="#L0A19">L0A19</a>         ; forward to SET-PROG
+        LD      A,H
+        OR      L
+        JR      Z,<A href="#L09F7">L09F7</a>         ; forward to CRT-NEW
+        LD      A,(IX+$04)      ; channel letter
+        CP      $CD             ; is character an inverted "M" ?
+        JR      NZ,<A href="#L09E2">L09E2</a>        ; forward to T-LD-NET
+        LD      HL,($5CE4)      ; sv D_STR2
+        JR      <A href="#L09EC">L09EC</a>           ; forward to RCLM-OLD
+; ---
+<a name="L09E2"></a>;; <b>T-LD-NET</b>
+L09E2:  BIT     3,(IY+$7C)      ; sv FLAGS_3
+        JR      Z,<A href="#L09EC">L09EC</a>         ; forward to RCLM-OLD
+        LD      DE,$0114
+        ADD     HL,DE
+<a name="L09EC"></a>;; <b>RCLM-OLD</b>
+L09EC:  DEC     HL
+        LD      B,(HL)
+        DEC     HL
+        LD      C,(HL)
+        DEC     HL
+        INC     BC
+        INC     BC
+        INC     BC
+        RST     10H             ; CALBAS
+        DEFW    $19E8           ; main RECLAIM-2
+<a name="L09F7"></a>;; <b>CRT-NEW</b>
+L09F7:  LD      HL,($5C59)      ; sv E_LINE
+        DEC     HL
+        LD      BC,($5CE7)      ; sv HD_0B
+        PUSH    BC
+        INC     BC
+        INC     BC
+        INC     BC
+        LD      A,($5CE3)       ; sv D_STR2
+        PUSH    AF
+        RST     10H             ; CALBAS
+        DEFW    $1655           ; main MAKE-ROOM
+        INC     HL
+        POP     AF
+        LD      (HL),A
+        POP     DE
+        INC     HL
+        LD      (HL),E
+        INC     HL
+        LD      (HL),D
+        INC     HL
+<a name="L0A13"></a>;; <b>END-LD-PR</b>
+L0A13:  CALL    <A href="#L0A60">L0A60</a>           ; routine LV-ANY
+        JP      <A href="#L098C">L098C</a>           ; jump to TST-MR-M
+; ---
+<a name="L0A19"></a>;; <b>SET-PROG</b>
+L0A19:  RES     1,(IY+$7C)      ; sv FLAGS_3
+        LD      DE,($5C53)      ; sv PROG
+        LD      HL,($5C59)      ; sv E_LINE
+        DEC     HL
+        RST     10H             ; CALBAS
+        DEFW    $19E5           ; main RECLAIM-1
+        LD      BC,($5CE7)      ; sv HD_0B
+        LD      HL,($5C53)      ; sv PROG
+        RST     10H             ; CALBAS
+        DEFW    $1655           ; main MAKE-ROOM
+        INC     HL
+        LD      BC,($5CEB)      ; sv HD_0F
+        ADD     HL,BC
+        LD      ($5C4B),HL      ; sv VARS
+        LD      A,($5CEE)       ; sv HD_11_hi
+        LD      H,A
+        AND     $C0
+        JR      NZ,<A href="#L0A52">L0A52</a>        ; forward to NO-AUTO
+        SET     1,(IY+$7C)      ; sv FLAGS_3
+        LD      A,($5CED)       ; sv HD_11
+        LD      L,A
+        LD      ($5C42),HL      ; sv NEWPPC
+        LD      (IY+$0A),$00    ; sv NSPPC
+<a name="L0A52"></a>;; <b>NO-AUTO</b>
+L0A52:  LD      HL,($5C53)      ; sv PROG
+        LD      DE,($5CE7)      ; sv HD_0B
+        DEC     HL
+        LD      ($5C57),HL      ; sv DATADD
+        INC     HL
+        JR      <A href="#L0A13">L0A13</a>           ; back to END-LD-PR
+; ----------------------------
+; THE <b><font color=#333388>'LOAD OR VERIFY'</font></b> ROUTINE
+; ----------------------------
+;   This routine is able to either LOAD or VERIFY a block of bytes, from any
+;   of the three possible binary sources, A Microdrive cartridge, the Binary
+;   "B" RS232 channel or the Network "N" channel.
+;   The block could be a program, code bytes or an array and the first
+;   receiving location is in HL and the length in DE.
+<a name="L0A60"></a>;; <b>LV-ANY</b>
+L0A60:  LD      A,D             ; test the length
+        OR      E               ; for zero.
+        RET     Z               ; return if so.
+        LD      A,(IX+$04)      ; fetch channel letter
+        CP      $CD             ; is letter "M" + $80 ?
+        JR      NZ,<A href="#L0A6E">L0A6E</a>        ; forward, if not, to LV-BN to load from
+                                ; the B channel or network.
+; else is a temporary "M" channel so load or verify and then return.
+        CALL    <A href="#L199A">L199A</a>           ; routine LV-MCH loads or verifies a block
+                                ; of code from microdrive.
+        RET                     ; return after called routine.
+; ---
+; Load or Verify from B channel or Network.
+<a name="L0A6E"></a>;; <b>LV-BN</b>
+L0A6E:  PUSH    HL              ; save address.
+        PUSH    DE              ; save byte count.
+        BIT     3,(IY+$7C)      ; test FLAGS_3 - using network ?
+        JR      Z,<A href="#L0A7D">L0A7D</a>         ; forward, if not, to LV-B
+; Load or Verify from "N" channel.
+<a name="L0A76"></a>;; <b>LV-N</b>
+L0A76:  CALL    <A href="#L0DAF">L0DAF</a>           ; routine NCHAN-IN
+        JR      NC,<A href="#L0A76">L0A76</a>        ; back to LV-N
+        JR      <A href="#L0A82">L0A82</a>           ; forward to LV-BN-E
+; ---
+; Load or Verify from "B" channel.
+<a name="L0A7D"></a>;; <b>LV-B</b>
+L0A7D:  CALL    <A href="#L0B88">L0B88</a>           ; routine BCHAN-IN
+        JR      NC,<A href="#L0A7D">L0A7D</a>        ; back to LV-B
+; Load or Verify "B","N" end test.
+<a name="L0A82"></a>;; <b>LV-BN-E</b>
+L0A82:  POP     DE              ; restore code length.
+        DEC     DE              ; and decrement.
+        POP     HL              ; restore load address.
+        BIT     7,(IY+$7C)      ; test FLAGS_3 - verify operation.
+        JR      NZ,<A href="#L0A8E">L0A8E</a>        ; forward, if so missing load, to VR-BN
+        LD      (HL),A          ; load the byte into memory.
+        JR      <A href="#L0A93">L0A93</a>           ; forward to LVBN-END
+; ---
+; Verify "B" or "N" bytes.
+<a name="L0A8E"></a>;; <b>VR-BN</b>
+L0A8E:  CP      (HL)            ; compare the received byte with the byte in
+                                ; memory.
+        JR      Z,<A href="#L0A93">L0A93</a>         ; forward, with match, to LVBN-END.
+        RST     20H             ; Shadow Error Restart
+        DEFB    $15             ; 'Verification has failed'
+; ---
+; Load or Verify "B","N" end.
+<a name="L0A93"></a>;; <b>LVBN-END</b>
+L0A93:  INC     HL              ; increment the address.
+        LD      A,E             ; test the byte
+        OR      D               ; counter for zero.
+        JR      NZ,<A href="#L0A6E">L0A6E</a>        ; back, if not, to LV-BN
+        RET                     ; return.
+; --------------------------------
+; THE <b><font color=#333388>'LOAD "RUN" PROGRAM'</font></b> ROUTINE
+; --------------------------------
+;
+<a name="L0A99"></a>;; <b>LOAD-RUN</b>
+L0A99:  LD      BC,$0001        ; set drive to one.
+        LD      ($5CD6),BC      ; update D_STR1 drive number.
+        LD      BC,$0003        ; length of "run" is three.
+        LD      ($5CDA),BC      ; update N_STR1 length of filename.
+        LD      BC,<A href="#L0ACA">L0ACA</a>        ; addr: NAME-RUN (below)
+        LD      ($5CDC),BC      ; update A_STR1 - address of filename.
+        SET     4,(IY+$7C)      ; update FLAGS_3 signal a LOAD operation.
+        CALL    <A href="#L0753">L0753</a>           ; routine PROG sets up the first seven header
+                                ; bytes for a program.
+        LD      HL,$5CE6        ; set start to HD_00
+        LD      DE,$5CDE        ; set destination to D_STR2
+        LD      BC,$0009        ; nine bytes are copied.
+                                ; <font color=#9900FF>Note.</font> should be seven but is mostly harmless.
+        LDIR                    ; block copy.
+        SET     7,(IY+$0A)      ; update Main NSPPC - signal no jump to be made.
+        CALL    <A href="#L1971">L1971</a>           ; routine F-M-HEAD loads the header type
+                                ; record for the 'run' file and populates
+                                ; the nine locations HD_00 to HD_11.
+        JP      <A href="#L08F6">L08F6</a>           ; jump back to TEST-TYPE to test that type is
+                                ; 'program' and load the rest.
+; ---
+<a name="L0ACA"></a>;; <b>NAME-RUN</b>
+L0ACA:  DEFM    "run"           ; the filename "run"
+; *******************************************
+; **  T H E   R S 2 3 2   R O U T I N E S  **
+; *******************************************
+; ----------------------------------------
+; THE <b><font color=#333388>'SET "BAUD" SYSTEM VARIABLE'</font></b> ROUTINE
+; ----------------------------------------
+;
+<a name="L0ACD"></a>;; <b>SET-BAUD</b>
+L0ACD:  LD      BC,($5CD6)      ; sv D_STR1 drive number
+        LD      HL,<A href="#L0AF3">L0AF3</a>        ; RS-CONSTS
+<a name="L0AD4"></a>;; <b>NXT-ENTRY</b>
+L0AD4:  LD      E,(HL)
+        INC     HL
+        LD      D,(HL)
+        INC     HL
+        EX      DE,HL
+        LD      A,H
+        CP      $4B             ;
+        JR      NC,<A href="#L0AE8">L0AE8</a>        ; forward to END-SET
+        AND     A
+        SBC     HL,BC
+        JR      NC,<A href="#L0AE8">L0AE8</a>        ; forward to END-SET
+        EX      DE,HL
+        INC     HL
+        INC     HL
+        JR      <A href="#L0AD4">L0AD4</a>           ; loop back to NXT-ENTRY
+; ---
+<a name="L0AE8"></a>;; <b>END-SET</b>
+L0AE8:  EX      DE,HL
+        LD      E,(HL)
+        INC     HL
+        LD      D,(HL)
+        LD      ($5CC3),DE      ; sv BAUD
+        JP      <A href="#L05C1">L05C1</a>           ; jump to END1
+; ------------------------------------
+; THE <b><font color=#333388>'RS232 TIMING CONSTANTS'</font></b> ROUTINE
+; ------------------------------------
+;
+<a name="L0AF3"></a>;; <b>RS-CONSTS</b>
+L0AF3:  DEFW    $0032           ;
+        DEFW    $0A82           ;
+        DEFW    $006E           ;
+        DEFW    $04C5           ;
+        DEFW    $012C           ;
+        DEFW    $01BE           ;
+        DEFW    $0258           ;
+        DEFW    $00DE           ;
+        DEFW    $04B0           ;
+        DEFW    $006E           ;
+        DEFW    $0960           ;
+        DEFW    $0036           ;
+        DEFW    $12C0           ;
+        DEFW    $001A           ;
+        DEFW    $2580           ;
+        DEFW    $000C           ;
+        DEFW    $4B00           ;
+        DEFW    $0005           ;
+; ----------------------------------------------
+; THE <b><font color=#333388>'OPEN RS232 CHANNEL IN CHANS AREA'</font></b> ROUTINE
+; ----------------------------------------------
+;
+<a name="L0B17"></a>;; <b>OP-RS-CH</b>
+L0B17:  LD      HL,($5C53)      ; use system variable PROG to address the
+                                ; location following the Channels area.
+        DEC     HL              ; step back to the end-marker.
+        LD      BC,$000B        ; eleven bytes of room required.
+        PUSH    BC              ; save bytes
+        RST     10H             ; CALBAS
+        DEFW    $1655           ; main routine MAKE-ROOM opens up the space.
+                                ; register HL points to location before room.
+        POP     BC              ; bring back the eleven bytes.
+        PUSH    DE              ; save DE briefly
+        CALL    <A href="#L1A82">L1A82</a>           ; routine REST-N-AD adjusts the dynamic memory
+                                ; pointers to filenames in D_STR1 and D_STR2.
+        POP     DE              ; restore DE.
+        LD      HL,<A href="#L0B76">L0B76</a> - 1    ; last byte of T-Channel info.
+        LD      BC,$000B        ; eleven bytes to copy.
+        LDDR                    ; block copy downwards.
+        INC     DE              ;
+        LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $42             ; is it "B" ?
+        RET     NZ              ; return as must be "T".
+; but if this is to be a binary channel then overwrite the letter and the output
+; and input routines.
+        PUSH    DE              ;
+        LD      HL,$0004        ;
+        ADD     HL,DE           ;
+        LD      (HL),$42        ; 'B'
+        INC     HL              ;
+        LD      DE,<A href="#L0D07">L0D07</a>        ; address B-CHAN-OUT
+        LD      (HL),E          ;
+        INC     HL              ;
+        LD      (HL),D          ;
+        INC     HL              ;
+        LD      DE,<A href="#L0B7C">L0B7C</a>        ; address B-INPUT
+        LD      (HL),E          ;
+        INC     HL              ;
+        LD      (HL),D          ;
+        POP     DE              ;
+        RET                     ; return.
+; ----------------------------------------
+; THE <b><font color=#333388>'ATTACH CHANNEL TO A STREAM'</font></b> ROUTINE
+; ----------------------------------------
+;
+<a name="L0B4E"></a>;; <b>OP-RSCHAN</b>
+L0B4E:  CALL    <A href="#L0B17">L0B17</a>           ; routine OP-RS-CH
+<a name="L0B51"></a>;; <b>OP-STREAM</b>
+L0B51:  LD      HL,($5C4F)      ; sv CHANS
+        DEC     HL
+        EX      DE,HL
+        AND     A
+        SBC     HL,DE
+        EX      DE,HL
+        LD      HL,$5C16        ; sv STRMS_00
+        LD      A,($5CD8)       ; sv D_STR1
+        RLCA
+        LD      C,A
+        LD      B,$00
+        ADD     HL,BC
+        LD      (HL),E
+        INC     HL
+        LD      (HL),D
+        JP      <A href="#L05C1">L05C1</a>           ; jump to END1
+; ----------------------
+; THE <b><font color=#333388>'"T" CHANNEL DATA'</font></b>
+; ----------------------
+; the eleven-byte "T" CHANNEL descriptor.
+<a name="L0B6B"></a>;; <b>TCHAN-DAT</b>
+L0B6B:  DEFW    $0008           ; main ERROR-1
+        DEFW    $0008           ; main ERROR-1
+        DEFB    $54             ; character "T"
+        DEFW    <A href="#L0C3A">L0C3A</a>           ; TCHAN-OUT
+        DEFW    <A href="#L0B76">L0B76</a>           ; T-INPUT
+        DEFW    $000B           ; channel length - 11 bytes.
+; -------------------------------
+; THE <b><font color=#333388>'"T" CHANNEL INPUT'</font></b> ROUTINE
+; -------------------------------
+;
+<a name="L0B76"></a>;; <b>T-INPUT</b>
+L0B76:  LD      HL,<A href="#L0B82">L0B82</a>        ; address of routine TCHAN-IN
+        JP      <A href="#L0D5A">L0D5A</a>           ; jump to CALL-INP
+; -------------------------------
+; THE <b><font color=#333388>'"B" CHANNEL INPUT'</font></b> ROUTINE
+; -------------------------------
+;
+<a name="L0B7C"></a>;; <b>B-INPUT</b>
+L0B7C:  LD      HL,<A href="#L0B88">L0B88</a>        ; address of routine BCHAN-IN
+        JP      <A href="#L0D5A">L0D5A</a>           ; jump to CALL-INP
+; ---------------------------------------
+; THE <b><font color=#333388>'"T" CHANNEL INPUT SERVICE'</font></b> ROUTINE
+; ---------------------------------------
+;
+<a name="L0B82"></a>;; <b>TCHAN-IN</b>
+L0B82:  CALL    <A href="#L0B88">L0B88</a>           ; routine BCHAN-IN
+        RES     7,A
+        RET
+; ---------------------------------------
+; THE <b><font color=#333388>'"B" CHANNEL INPUT SERVICE'</font></b> ROUTINE
+; ---------------------------------------
+; <font color=#339933>(Hook Code: $1D)</font>
+<a name="L0B88"></a>;; <b>BCHAN-IN</b>
+L0B88:  LD      HL,$5CC7        ; sv SER_FL
+        LD      A,(HL)          ;
+        AND     A               ;
+        JR      Z,<A href="#L0B95">L0B95</a>         ; forward to REC-BYTE
+        LD      (HL),$00        ;
+        INC     HL              ;
+        LD      A,(HL)          ;
+        SCF                     ;
+        RET                     ; Return.
+; ---
+<a name="L0B95"></a>;; <b>REC-BYTE</b>
+L0B95:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+        DI                      ; Disable Interrupts
+        LD      A,($5CC6)       ; sv IOBORD
+        OUT     ($FE),A
+        LD      DE,($5CC3)      ; sv BAUD
+        LD      HL,$0320        ; 800d.
+        LD      B,D             ;
+        LD      C,E             ;
+        SRL     B               ;
+        RR      C               ;
+        LD      A,$FE           ;
+        OUT     ($EF),A         ;
+<a name="L0BAF"></a>;; <b>READ-RS</b>
+L0BAF:  IN      A,($F7)         ; bit 7 is input serial data (txdata)
+        RLCA                    ;
+        JR      NC,<A href="#L0BC3">L0BC3</a>        ; forward to TST-AGAIN
+        IN      A,($F7)         ;
+        RLCA                    ;
+        JR      NC,<A href="#L0BC3">L0BC3</a>        ; forward to TST-AGAIN
+        IN      A,($F7)         ;
+        RLCA                    ;
+        JR      NC,<A href="#L0BC3">L0BC3</a>        ; forward to TST-AGAIN
+        IN      A,($F7)         ;
+        RLCA                    ;
+        JR      C,<A href="#L0BCF">L0BCF</a>         ; forward to START-BIT
+<a name="L0BC3"></a>;; <b>TST-AGAIN</b>
+L0BC3:  DEC     HL              ;
+        LD      A,H             ;
+        OR      L               ;
+        JR      NZ,<A href="#L0BAF">L0BAF</a>        ; back to READ-RS
+        PUSH    AF              ;
+        LD      A,$EE           ;
+        OUT     ($EF),A         ;
+        JR      <A href="#L0BEE">L0BEE</a>           ; forward to WAIT-1
+; ---
+<a name="L0BCF"></a>;; <b>START-BIT</b>
+L0BCF:  LD      H,B             ; Load HL with halved BAUD value.
+        LD      L,C             ;
+        LD      B,$80           ; Load B with the start bit.
+        DEC     HL              ; Reduce the counter by the time for the four
+        DEC     HL              ; tests.
+        DEC     HL              ;
+<a name="L0BD6"></a>;; <b>SERIAL-IN</b>
+L0BD6:  ADD     HL,DE           ; Add the BAUD value.
+        NOP                     ; (4) a timing value.
+<a name="L0BD8"></a>;; <b>BD-DELAY</b>
+L0BD8:  DEC     HL              ; (6) Delay for 26 * BAUD
+        LD      A,H             ; (4)
+        OR      L               ; (4)
+        JR      NZ,<A href="#L0BD8">L0BD8</a>        ; (12) back to BD-DELAY
+        ADD     A,$00           ; (7) wait
+        IN      A,($F7)         ; Read a bit.
+        RLCA                    ; Rotate bit 7 to carry.
+        RR      B               ; pick up carry in B
+        JR      NC,<A href="#L0BD6">L0BD6</a>        ; back , if no start bit, to SERIAL-IN
+        LD      A,$EE           ; Send CTS line low  (comms data 0 also)
+        OUT     ($EF),A         ; send to serial port
+        LD      A,B             ; Transfer the received byte to A.
+        CPL                     ; Complement.
+        SCF                     ; Set Carry to signal success.
+        PUSH    AF              ; (*) push the success flag.
+;   The success and failure (time out) paths converge here with the HL register
+;   holding zero.
+<a name="L0BEE"></a>;; <b>WAIT-1</b>
+L0BEE:  ADD     HL,DE           ; (11) transfer DE (BAUD) to HL.
+<a name="L0BEF"></a>;; <b>WAIT-2</b>
+L0BEF:  DEC     HL              ; ( 6) delay for stop bit.
+        LD      A,L             ; ( 4)
+        OR      H               ; ( 4)
+        JR      NZ,<A href="#L0BEF">L0BEF</a>        ; (12/7) back to WAIT-2
+;   Register HL is now zero again.
+        ADD     HL,DE           ; HL = 0 + BAUD
+        ADD     HL,DE           ; HL = 2 * BAUD
+        ADD     HL,DE           ; HL = 3 * BAUD
+;   The device at the other end of the cable (not a Spectrum) may send a
+;   second byte even though CTS (Clear To Send) is low.
+<a name="L0BF7"></a>;; <b>T-FURTHER</b>
+L0BF7:  DEC     HL              ; Decrement counter.
+        LD      A,L             ; Test for
+        OR      H               ; zero.
+        JR      Z,<A href="#L0C34">L0C34</a>         ; forward, if no second byte, to END-RS-IN
+        IN      A,($F7)         ; Read TXdata.
+        RLCA                    ; test the bit read.
+        JR      NC,<A href="#L0BF7">L0BF7</a>        ; back, if none,  to T-FURTHER
+;   As with first byte, TXdata must be high four four tests.
+        IN      A,($F7)         ;
+        RLCA                    ;
+        JR      NC,<A href="#L0BF7">L0BF7</a>        ; back to T-FURTHER
+        IN      A,($F7)         ;
+        RLCA                    ;
+        JR      NC,<A href="#L0BF7">L0BF7</a>        ; back to T-FURTHER
+        IN      A,($F7)         ;
+        RLCA                    ;
+        JR      NC,<A href="#L0BF7">L0BF7</a>        ; back to T-FURTHER
+;   A second byte is on its way and is received exactly as before.
+        LD      H,D             ;
+        LD      L,E             ;
+        SRL     H               ;
+        RR      L               ;
+        LD      B,$80           ;
+        DEC     HL              ;
+        DEC     HL              ;
+        DEC     HL              ;
+<a name="L0C1B"></a>;; <b>SER-IN-2</b>
+L0C1B:  ADD     HL,DE           ;
+        NOP                     ; timing.
+<a name="L0C1D"></a>;; <b>BD-DELAY2</b>
+L0C1D:  DEC     HL              ;
+        LD      A,H             ;
+        OR      L               ;
+        JR      NZ,<A href="#L0C1D">L0C1D</a>        ; back to BD-DELAY2
+        ADD     A,$00           ;
+        IN      A,($F7)         ;
+        RLCA                    ;
+        RR      B               ;
+        JR      NC,<A href="#L0C1B">L0C1B</a>        ; back to SER-IN-2
+;  The start bit has been pushed out and B contains the second received byte.
+        LD      HL,$5CC7        ; Address the SER_FL System Variable.
+        LD      (HL),$01        ; Signal there is a byte in the next location.
+        INC     HL              ; Address that location.
+        LD      A,B             ; Transfer the byte to A.
+        CPL                     ; Complement
+        LD      (HL),A          ; and insert in the second byte of serial flag.
+<a name="L0C34"></a>;; <b>END-RS-IN</b>
+L0C34:  CALL    <A href="#L0D4D">L0D4D</a>           ; routine BORD-REST
+        POP     AF              ; ( either 0 and NC or the first received byte
+                                ;   and the carry flag set )
+        EI                      ; Enable Interrupts
+        RET                     ; Return.
+; --------------------------------
+; THE <b><font color=#333388>'"T" CHANNEL OUTPUT'</font></b> ROUTINE
+; --------------------------------
+;   The text channel output routine is able to list programs and, when
+;   printing, takes correct action with TAB values etc.
+<a name="L0C3A"></a>;; <b>TCHAN-OUT</b>
+L0C3A:  CP      $A5             ; 'RND' - first token
+        JR      C,<A href="#L0C44">L0C44</a>         ; forward, if less, to NOT-TOKEN
+        SUB     $A5             ; reduce to range $00-5A
+        RST     10H             ; CALBAS
+        DEFW    $0C10           ; main PO-TOKENS
+        RET                     ; return.
+; ---
+<a name="L0C44"></a>;; <b>NOT-TOKEN</b>
+L0C44:  LD      HL,$5C3B        ; Address the FLAGS System Variable.
+        RES     0,(HL)          ; update FLAGS - allow for leading space.
+        CP      $20             ; compare to space
+        JR      NZ,<A href="#L0C4F">L0C4F</a>        ; forward, if not, to NOT-LEAD
+        SET     0,(HL)          ; update FLAGS - signal suppress leading space.
+<a name="L0C4F"></a>;; <b>NOT-LEAD</b>
+L0C4F:  CP      $7F             ; compare to copyright symbol. (DEL in ASCII)
+        JR      C,<A href="#L0C55">L0C55</a>         ; forward, if less, to NOT-GRAPH
+        LD      A,$3F           ; output CHR$(127) and graphics as '?'
+<a name="L0C55"></a>;; <b>NOT-GRAPH</b>
+L0C55:  CP      $20             ; compare against space.
+        JR      C,<A href="#L0C70">L0C70</a>         ; forward to CTRL-CD
+        PUSH    AF              ; Preserve character.
+        INC     (IY+$76)        ; Increment width         NMI_ADD_lo
+        LD      A,($5CB1)       ; Load A with limit from  NMI_ADD_hi
+        CP      (IY+$76)        ; Compare to width        NMI_ADD_lo
+        JR      NC,<A href="#L0C6C">L0C6C</a>        ; forward, if less or equal, to EMIT-CH
+        CALL    <A href="#L0C74">L0C74</a>           ; routine TAB-SETZ emits CR/LF.
+        LD      (IY+$76),$01    ; Set width to one        NMI_ADD_lo
+<a name="L0C6C"></a>;; <b>EMIT-CH</b>
+L0C6C:  POP     AF              ; Restore the unprinted character.
+        JP      <A href="#L0D07">L0D07</a>           ; jump to BCHAN-OUT
+; ---
+<a name="L0C70"></a>;; <b>CTRL-CD</b>
+L0C70:  CP      $0D             ; carriage return ?
+        JR      NZ,<A href="#L0C82">L0C82</a>        ; forward to NOT-CR
+<a name="L0C74"></a>;; <b>TAB-SETZ</b>
+L0C74:  LD      (IY+$76),$00    ; sv NMI_ADD_lo
+        LD      A,$0D           ; output a CR carriage return.
+        CALL    <A href="#L0D07">L0D07</a>           ; routine BCHAN-OUT
+        LD      A,$0A           ; output a LF line feed.
+        JP      <A href="#L0D07">L0D07</a>           ; jump to BCHAN-OUT
+; ---
+<a name="L0C82"></a>;; <b>NOT-CR</b>
+L0C82:  CP      $06             ;
+        JR      NZ,<A href="#L0CA5">L0CA5</a>        ; forward to NOT-CMM
+        LD      BC,($5CB0)      ; sv NMI_ADD
+        LD      E,$00           ;
+<a name="L0C8C"></a>;; <b>SPC-COUNT</b>
+L0C8C:  INC     E
+        INC     C
+        LD      A,C
+        CP      B
+        JR      Z,<A href="#L0C9A">L0C9A</a>         ; forward to CMM-LP2
+<a name="L0C92"></a>;; <b>CMM-LOOP</b>
+L0C92:  SUB     $08
+        JR      Z,<A href="#L0C9A">L0C9A</a>         ; forward to CMM-LP2
+        JR      NC,<A href="#L0C92">L0C92</a>        ; back to CMM-LOOP
+        JR      <A href="#L0C8C">L0C8C</a>           ; back to SPC-COUNT
+<a name="L0C9A"></a>;; <b>CMM-LP2</b>
+L0C9A:  PUSH    DE
+        LD      A,$20
+        CALL    <A href="#L0C3A">L0C3A</a>           ; routine TCHAN-OUT
+        POP     DE
+        DEC     E
+        RET     Z
+        JR      <A href="#L0C9A">L0C9A</a>           ; back to CMM-LP2
+; ---
+<a name="L0CA5"></a>;; <b>NOT-CMM</b>
+L0CA5:  CP      $16
+        JR      Z,<A href="#L0CB5">L0CB5</a>         ; forward to TAB-PROC
+        CP      $17
+        JR      Z,<A href="#L0CB5">L0CB5</a>         ; forward to TAB-PROC
+        CP      $10
+        RET     C
+        LD      DE,$0CD0
+        JR      <A href="#L0CB8">L0CB8</a>           ; forward to STORE-COD
+; ---
+<a name="L0CB5"></a>;; <b>TAB-PROC</b>
+L0CB5:  LD      DE,<A href="#L0CC8">L0CC8</a>        ; addr: TAB-SERV
+<a name="L0CB8"></a>;; <b>STORE-COD</b>
+L0CB8:  LD      ($5C0E),A       ; sv TVDATA
+<a name="L0CBB"></a>;; <b>ALTER-OUT</b>
+L0CBB:  LD      HL,($5C51)      ; sv CURCHL
+        PUSH    DE
+        LD      DE,$0005
+        ADD     HL,DE
+        POP     DE
+        LD      (HL),E
+        INC     HL
+        LD      (HL),D
+        RET
+; ---
+<a name="L0CC8"></a>;; <b>TAB-SERV</b>
+L0CC8:  LD      DE,<A href="#L0CD0">L0CD0</a>        ; addr: TAB-SERV2
+        LD      ($5C0F),A       ; sv TVDATA
+        JR      <A href="#L0CBB">L0CBB</a>           ; back to ALTER-OUT
+; ---
+<a name="L0CD0"></a>;; <b>TAB-SERV2</b>
+L0CD0:  LD      DE,<A href="#L0C3A">L0C3A</a>        ; addr: TCHAN-OUT
+        CALL    <A href="#L0CBB">L0CBB</a>           ; routine ALTER-OUT
+        LD      D,A
+        LD      A,($5C0E)       ; sv TVDATA
+        CP      $16             ; AT control code ?
+        JR      Z,<A href="#L0CE6">L0CE6</a>         ; forward to TST-WIDTH
+        CP      $17             ; TAB control code ?
+        CCF
+        RET     NZ
+        LD      A,($5C0F)       ; sv TVDATA
+        LD      D,A
+<a name="L0CE6"></a>;; <b>TST-WIDTH</b>
+L0CE6:  LD      A,($5CB1)       ; sv NMI_ADD
+        CP      D
+        JR      Z,<A href="#L0CEE">L0CEE</a>         ; forward to TAB-MOD
+        JR      NC,<A href="#L0CF4">L0CF4</a>        ; forward to TABZERO
+<a name="L0CEE"></a>;; <b>TAB-MOD</b>
+L0CEE:  LD      B,A
+        LD      A,D
+        SUB     B
+        LD      D,A
+        JR      <A href="#L0CE6">L0CE6</a>           ; back to TST-WIDTH
+; ---
+<a name="L0CF4"></a>;; <b>TABZERO</b>
+L0CF4:  LD      A,D
+        OR      A
+        JP      Z,<A href="#L0C74">L0C74</a>         ; jump to TAB-SETZ
+<a name="L0CF9"></a>;; <b>TABLOOP</b>
+L0CF9:  LD      A,($5CB0)       ; sv NMI_ADD_lo
+        CP      D               ;
+        RET     Z               ;
+        PUSH    DE              ;
+        LD      A,$20           ;
+        CALL    <A href="#L0C3A">L0C3A</a>           ; routine TCHAN-OUT
+        POP     DE              ;
+        JR      <A href="#L0CF9">L0CF9</a>           ; back to TABLOOP
+; --------------------------------
+; THE <b><font color=#333388>'"B" CHANNEL OUTPUT'</font></b> ROUTINE
+; --------------------------------
+; <font color=#339933>(Hook Code: $1E)</font>
+;   The bits of a byte are sent inverted. They are fixed in length and heralded
+;   by a start bit and followed by two stop bits.
+<a name="L0D07"></a>;; <b>BCHAN-OUT</b>
+L0D07:  LD      B,$0B           ; Set bit count to eleven - 1 + 8 + 2.
+        CPL                     ; Invert the bits of the character.
+        LD      C,A             ; Copy the character to C.
+        LD      A,($5CC6)       ; Load A from System Variable IOBORD
+        OUT     ($FE),A         ; Change the border colour.
+        LD      A,$EF           ; Set to %11101111
+        OUT     ($EF),A         ; Make CTS (Clear to Send) low.
+        CPL                     ; reset bit 0 (other bits of no importance)
+        OUT     ($F7),A         ; Make RXdata low. %00010000
+        LD      HL,($5CC3)      ; Fetch value from BAUD System Variable.
+        LD      D,H             ; Copy BAUD value to DE for count.
+        LD      E,L             ;
+<a name="L0D1C"></a>;; <b>BD-DEL-1</b>
+L0D1C:  DEC     DE              ; ( 6) Wait 26 * BAUD cycles
+        LD      A,D             ; ( 4)
+        OR      E               ; ( 4)
+        JR      NZ,<A href="#L0D1C">L0D1C</a>        ; (12) back to BD-DEL-1
+<a name="L0D21"></a>;; <b>TEST-DTR</b>
+L0D21:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK allows user to stop.
+        IN      A,($EF)         ; Read the communication port.
+        AND     $08             ; isolate DTR (Data Terminal Ready) bit.
+        JR      Z,<A href="#L0D21">L0D21</a>         ; back, until DTR found high, to TEST-DTR
+        SCF                     ; Set carry flag as the start bit.
+        DI                      ; Disable Interrupts.
+<a name="L0D2C"></a>;; <b>SER-OUT-L</b>
+L0D2C:  ADC     A,$00           ; Set bit 0            76543210 &lt;- C
+        OUT     ($F7),A         ; Send RXdata the start bit.
+        LD      D,H             ; Transfer the BAUD value to DE for count.
+        LD      E,L             ;
+<a name="L0D32"></a>;; <b>BD-DEL-2</b>
+L0D32:  DEC     DE              ; ( 6) Wait for 26 * BAUD
+        LD      A,D             ; ( 4)
+        OR      E               ; ( 4)
+        JR      NZ,<A href="#L0D32">L0D32</a>        ; (12) back to BD-DEL-2
+        DEC     DE              ; ( 6)
+        XOR     A               ; ( 4) clear rxdata bit
+        SRL     C               ;      shift a bit of output byte to carry.
+        DJNZ    <A href="#L0D2C">L0D2C</a>           ; back for 11 bits to SER-OUT-L
+;   Note the last two bits will have been sent reset as C is exhausted.
+        EI                      ; Enable Interrupts.
+        LD      A,$01           ; Set RXdata
+        LD      C,$EF           ; prepare port address.
+        LD      B,$EE           ; prepare value %11101110
+        OUT     ($F7),A         ; Send RXdata high.
+        OUT     (C),B           ; Send CTS and comms data low - switch off RS232
+<a name="L0D48"></a>;; <b>BD-DEL-3</b>
+L0D48:  DEC     HL              ; ( 6) The final 26 * BAUD delay
+        LD      A,L             ; ( 4)
+        OR      H               ; ( 4)
+        JR      NZ,<A href="#L0D48">L0D48</a>        ; (12) back to BD-DEL-3
+; -----------------------------------
+; THE <b><font color=#333388>'BORDER COLOUR RESTORE'</font></b> ROUTINE
+; -----------------------------------
+;
+<a name="L0D4D"></a>;; <b>BORD-REST</b>
+L0D4D:  PUSH    AF              ; Preserve the accumulator value throughout.
+        LD      A,($5C48)       ; Fetch System Variable BORDCR
+        AND     $38             ; Mask off the paper bits.
+        RRCA                    ; Rotate to the range 0 - 7
+        RRCA                    ;
+        RRCA                    ;
+        OUT     ($FE),A         ; Change the border colour.
+        POP     AF              ; Restore accumulator and flags.
+        RET                     ; Return.
+; ----------------------
+; THE <b><font color=#333388>'CALL-INP'</font></b> ROUTINE
+; ----------------------
+;   If the extended streams e.g. #7 are being used for input then this ROM
+;   will be paged in as a result of the $0008 address in the normal INPUT
+;   channel position. Since 'INPUT #7' or 'INKEYS #7' could have been used
+;   it is the purpose of this routine to determine which has been used.
+;   Note also that 'MOVE #7 TO #2' could also invoke this routine and that MOVE
+;   operations are further differentiated in the INKEY$ branch.
+<a name="L0D5A"></a>;; <b>CALL-INP</b>
+L0D5A:  RES     3,(IY+$02)      ; update TV_FLAG - The mode is to be considered
+                                ; unchanged.
+                                ; <font color=#9900FF>Note.</font> this should have been done by the Main
+                                ; ROM before entering the EDITOR.
+        PUSH    HL              ; (*) Preserve HL the address of the actual
+                                ; service routine - either NCHAN_IN, MCHAN_IN,
+                                ; BCHAN_IN ot T_CHAN_IN.
+        LD      HL,($5C3D)      ; Fetch address of Error Stack Pointer ERR_SP
+        LD      E,(HL)          ; Extract the address of the error handler
+        INC     HL              ; If INPUT is being used this will be
+        LD      D,(HL)          ; address $107F in the Main ROM.
+        AND     A               ; Prepare to subtract.
+        LD      HL,$107F        ; address of ED-ERROR in the Main ROM
+        SBC     HL,DE           ; subtract from test value.
+        JR      NZ,<A href="#L0D98">L0D98</a>        ; forward if not in EDITOR to INKEY$
+;   continue to handle INPUT from a stream.
+        POP     HL              ; (*) POP service routine to HL e.g. NCHAN_IN
+        LD      SP,($5C3D)      ; set Stack Pointer from System Variable ERR_SP
+        POP     DE              ; discard the known ED-ERROR address $107F.
+        POP     DE              ; POP the next value in hierarchy - MAIN-4
+                                ; (usually).
+        LD      ($5C3D),DE      ; and set the system variable ERR_SP
+<a name="L0D78"></a>;; <b>IN-AGAIN.</b>
+L0D78:  PUSH    HL              ; Push the address of the service routine
+                                ; e.g. NCHAN_IN on the machine stack.
+        LD      DE,<A href="#L0D7E">L0D7E</a>        ; addr: IN-AG-RET (below)
+        PUSH    DE              ; push this address
+        JP      (HL)            ; jump to the service routine either MCHAN_IN,
+                                ; NCHAN_IN, BCHAN_IN or TCHAN_IN and then return
+                                ; to the next address IN-AG-RET.
+; ---
+<a name="L0D7E"></a>;; <b>IN-AG-RET</b>
+L0D7E   JR      C,<A href="#L0D8A">L0D8A</a>         ; forward with acceptable codes to ACC-CODE
+        JR      Z,<A href="#L0D87">L0D87</a>         ; forward with time-out to NO-READ
+;   Otherwise Iris has closed her channel or the microdrive file was exhausted.
+<a name="L0D82"></a>;; <b>OREPORT-8</b>
+L0D82:  LD      (IY+$00),$07    ; set ERR_NR to  '8 End of file'
+        RST     28H             ; Error Main ROM.
+; ---
+<a name="L0D87"></a>;; <b>NO-READ</b>
+L0D87:  POP     HL              ; Retrieve the address of teh service routine
+                                ; and try again as always for INPUT.
+        JR      <A href="#L0D78">L0D78</a>           ; back to IN-AGAIN.
+; ---
+<a name="L0D8A"></a>;; <b>ACC-CODE</b>
+L0D8A:  CP      $0D             ; Is the acceptable code ENTER?
+        JR      Z,<A href="#L0D94">L0D94</a>         ; forward, if so, to END-INPUT
+        RST     10H             ; CALBAS - Call the Base ROM.
+        DEFW    $0F85           ; main ADD-CHRX
+                                ; A special entry point within ADD-CHAR to add
+                                ; the character to WORKSPACE.
+        POP     HL              ; Retrieve the address of the saved service
+                                ; routine.
+        JR      <A href="#L0D78">L0D78</a>           ; back for another character to IN-AGAIN.
+; ---
+<a name="L0D94"></a>;; <b>END-INPUT</b>
+L0D94:  POP     HL              ; Discard the service routine.
+        JP      <A href="#L0700">L0700</a>           ; jump to UNPAGE
+; -------------------
+; THE <b><font color=#333388>'INKEY$'</font></b> BRANCH
+; -------------------
+<a name="L0D98"></a>;; <b>INKEY$</b>
+L0D98:  POP     HL              ; (*) POP service routine to HL e.g. NCHAN_IN
+        LD      DE,<A href="#L0D9E">L0D9E</a>        ; ret addr. INK-RET (below)
+        PUSH    DE              ; push this address for the return address.
+        JP      (HL)            ; jump to the service routine either MCHAN_IN,
+                                ; NCHAN_IN, BCHAN_IN or TCHAN_IN and then return
+                                ; to the next address IN-AG-RET.
+; ---
+<a name="L0D9E"></a>;; <b>INK-RET</b>
+L0D9E   RET     C               ; Return with acceptable character.
+        RET     Z               ; Return with no character.
+        BIT     4,(IY+$7C)      ; sv FLAGS_3               MOVE?
+        JR      Z,<A href="#L0D82">L0D82</a>         ; back to OREPORT-8
+        OR      $01             ;
+        RET                     ; return with zero and carry reset.
+; ***********************************************
+; **  T H E   N E T W O R K   R O U T I N E S  **
+; ***********************************************
+; -------------------------------
+; THE <b><font color=#333388>'"N" CHANNEL INPUT'</font></b> ROUTINE
+; -------------------------------
+;
+<a name="L0DA9"></a>;; <b>N-INPUT</b>
+L0DA9:  LD      HL,<A href="#L0DAF">L0DAF</a>        ; Address: NCHAN-IN
+        JP      <A href="#L0D5A">L0D5A</a>           ; jump to CALL-INP
+; ---------------------------------------
+; THE <b><font color=#333388>'"N" CHANNEL INPUT SERVICE'</font></b> ROUTINE
+; ---------------------------------------
+;
+<a name="L0DAF"></a>;; <b>NCHAN-IN</b>
+L0DAF:  LD      IX,($5C51)      ; sv CURCHL
+        LD      A,(IX+$10)      ; NCOBL
+        AND     A
+        JR      Z,<A href="#L0DBB">L0DBB</a>         ; forward to TEST-BUFF
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0D             ; Reading a 'write' file
+; ---
+<a name="L0DBB"></a>;; <b>TEST-BUFF</b>
+L0DBB:  LD      A,(IX+$14)      ; NCIBL
+        AND     A
+        JR      Z,<A href="#L0DD5">L0DD5</a>         ; forward to TST-N-EOF
+        LD      E,(IX+$13)      ; NCCUR
+        DEC     A
+        SUB     E
+        JR      C,<A href="#L0DD5">L0DD5</a>         ; forward to TST-N-EOF
+        LD      D,$00
+        INC     E
+        LD      (IX+$13),E      ; NCCUR
+        ADD     IX,DE
+        LD      A,(IX+$14)      ;
+        SCF
+        RET
+; ---
+<a name="L0DD5"></a>;; <b>TST-N-EOF</b>
+L0DD5:  LD      A,(IX+$0F)      ; NCTYPE
+        AND     A
+        JR      Z,<A href="#L0DDC">L0DDC</a>         ; forward to GET-N-BUF
+        RET
+; ---
+<a name="L0DDC"></a>;; <b>GET-N-BUF</b>
+L0DDC:  LD      A,($5CC6)       ; sv IOBORD
+        OUT     ($FE),A
+        DI
+<a name="L0DE2"></a>;; <b>TRY-AGAIN</b>
+L0DE2:  CALL    <A href="#L0FD3">L0FD3</a>           ; routine WT-SC-E
+        JR      NC,<A href="#L0DFC">L0DFC</a>        ; forward to TIME-OUT
+        CALL    <A href="#L0EB5">L0EB5</a>           ; routine GET-NBLK
+        JR      NZ,<A href="#L0DFC">L0DFC</a>        ; forward to TIME-OUT
+        EI
+        CALL    <A href="#L0D4D">L0D4D</a>           ; routine BORD-REST
+        LD      (IX+$13),$00    ; NCCUR
+        LD      A,($5CD2)       ; sv NTTYPE
+        LD      (IX+$0F),A      ; NCTYPE
+        JR      <A href="#L0DBB">L0DBB</a>           ; back to TEST-BUFF
+; ---
+<a name="L0DFC"></a>;; <b>TIME-OUT</b>
+L0DFC:  LD      A,(IX+$0B)      ; NCIRIS
+        AND     A               ;
+        JR      Z,<A href="#L0DE2">L0DE2</a>         ; back to TRY-AGAIN
+        EI                      ;
+        CALL    <A href="#L0D4D">L0D4D</a>           ; routine BORD-REST
+        AND     $00             ;
+        RET                     ;
+; --------------------------------
+; THE <b><font color=#333388>'"N" CHANNEL OUTPUT'</font></b> ROUTINE
+; --------------------------------
+;
+<a name="L0E09"></a>;; <b>NCHAN-OUT</b>
+L0E09:  LD      IX,($5C51)      ; sv CURCHL
+        LD      B,A
+        LD      A,(IX+$14)      ; NCIBL
+        AND     A
+        LD      A,B
+        JR      Z,<A href="#L0E17">L0E17</a>         ; forward to TEST-OUT
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0C             ; Writing to a 'read' file
+<a name="L0E17"></a>;; <b>TEST-OUT</b>
+L0E17:  LD      E,(IX+$10)      ; NCOBL
+        INC     E               ;
+        JR      NZ,<A href="#L0E25">L0E25</a>        ; forward to ST-BF-LEN
+        PUSH    AF              ;
+        XOR     A               ;
+        CALL    <A href="#L0E48">L0E48</a>           ; routine S-PACK-1
+        POP     AF              ;
+        LD      E,$01           ;
+<a name="L0E25"></a>;; <b>ST-BF-LEN</b>
+L0E25:  LD      (IX+$10),E      ; NCOBL
+        LD      D,$00           ;
+        ADD     IX,DE           ;
+        LD      (IX+$14),A      ; NCIBL
+        RET                     ;
+; -----------------------
+; THE <b><font color=#333388>'OUT-BLK-N'</font></b> ROUTINE
+; -----------------------
+;
+<a name="L0E30"></a>;; <b>OUT-BLK-N</b>
+L0E30:  CALL    <A href="#L1082">L1082</a>           ; routine OUTPAK
+        LD      A,(IX+$0B)      ; NCIRIS
+        AND     A               ;
+        RET     Z               ;
+        LD      HL,$5CCD        ; sv NTRESP
+        LD      (HL),$00        ;
+        LD      E,$01           ;
+        CALL    <A href="#L104F">L104F</a>           ; routine INPAK
+        RET     NZ              ;
+        LD      A,($5CCD)       ; sv NTRESP
+        DEC     A               ;
+        RET                     ;
+; ----------------------
+; THE <b><font color=#333388>'S-PACK-1'</font></b> ROUTINE
+; ----------------------
+;
+<a name="L0E48"></a>;; <b>S-PACK-1</b>
+L0E48:  CALL    <A href="#L0E4F">L0E4F</a>           ; routine SEND-PACK
+        RET     NZ              ;
+        JP      <A href="#L0EAC">L0EAC</a>           ; jump to BR-DELAY
+; -----------------------
+; THE <b><font color=#333388>'SEND-PACK'</font></b> ROUTINE
+; -----------------------
+; <font color=#339933>(Hook Code: $30)</font>
+<a name="L0E4F"></a>;; <b>SEND-PACK</b>
+L0E4F:  LD      (IX+$0F),A      ; NCTYPE
+        LD      B,(IX+$10)      ; NCOBL
+        LD      A,($5CC6)       ; sv IOBORD
+        OUT     ($FE),A         ;
+        PUSH    IX              ;
+        POP     DE              ;
+        LD      HL,$0015        ;
+        ADD     HL,DE           ;
+        XOR     A               ;
+<a name="L0E62"></a>;; <b>CHKS1</b>
+L0E62:  ADD     A,(HL)          ;
+        INC     HL              ;
+        DJNZ    <A href="#L0E62">L0E62</a>           ; back to CHKS1
+        LD      (IX+$11),A      ; NCDCS
+        LD      HL,$000B        ;
+        ADD     HL,DE           ;
+        PUSH    HL              ;
+        LD      B,$07           ;
+        XOR     A               ;
+<a name="L0E71"></a>;; <b>CHKS2</b>
+L0E71:  ADD     A,(HL)          ;
+        INC     HL              ;
+        DJNZ    <A href="#L0E71">L0E71</a>           ; back to CHKS2
+        LD      (HL),A          ;
+        DI                      ;
+<a name="L0E77"></a>;; <b>SENDSCOUT</b>
+L0E77:  CALL    <A href="#L101E">L101E</a>           ; routine SEND-SC
+        POP     HL              ;
+        PUSH    HL              ;
+        LD      E,$08           ;
+        CALL    <A href="#L0E30">L0E30</a>           ; routine OUT-BLK-N
+        JR      NZ,<A href="#L0E77">L0E77</a>        ; back to SENDSCOUT
+        PUSH    IX              ;
+        POP     HL              ;
+        LD      DE,$0015        ;
+        ADD     HL,DE           ;
+        LD      E,(IX+$10)      ; NCOBL
+        LD      A,E             ;
+        AND     A               ;
+        JR      Z,<A href="#L0E9A">L0E9A</a>         ; forward to INC-BLKN
+        LD      B,$20           ;
+<a name="L0E93"></a>;; <b>SP-DL-1</b>
+L0E93:  DJNZ    <A href="#L0E93">L0E93</a>           ; back to SP-DL-1
+        CALL    <A href="#L0E30">L0E30</a>           ; routine OUT-BLK-N
+        JR      NZ,<A href="#L0E77">L0E77</a>        ; back to SENDSCOUT
+<a name="L0E9A"></a>;; <b>INC-BLKN</b>
+L0E9A:  INC     (IX+$0D)        ; NCNUMB
+        JR      NZ,<A href="#L0EA2">L0EA2</a>        ; forward to SP-N-END
+        INC     (IX+$0E)        ; NCNUMB_hi
+<a name="L0EA2"></a>;; <b>SP-N-END</b>
+L0EA2:  POP     HL              ;
+        CALL    <A href="#L0D4D">L0D4D</a>           ; routine BORD-REST
+        EI                      ;
+        LD      A,(IX+$0B)      ; NCIRIS
+        AND     A               ;
+        RET                     ;
+; ----------------------
+; THE <b><font color=#333388>'BR-DELAY'</font></b> ROUTINE
+; ----------------------
+;
+<a name="L0EAC"></a>;; <b>BR-DELAY</b>
+L0EAC:  LD      DE,$1500        ;
+<a name="L0EAF"></a>;; <b>DL-LOOP</b>
+L0EAF:  DEC     DE              ;
+        LD      A,E             ;
+        OR      D               ;
+        JR      NZ,<A href="#L0EAF">L0EAF</a>        ; back to DL-LOOP
+        RET                     ;
+; ---------------------------------------------
+; THE <b><font color=#333388>'HEADER AND DATA BLOCK RECEIVING'</font></b> ROUTINE
+; ---------------------------------------------
+;
+<a name="L0EB5"></a>;; <b>GET-NBLK</b>
+L0EB5:  LD      HL,$5CCE        ; sv NTDEST
+        LD      E,$08
+        CALL    <A href="#L104F">L104F</a>           ; routine INPAK
+        RET     NZ
+        LD      HL,$5CCE        ; sv NTDEST
+        XOR     A
+        LD      B,$07
+<a name="L0EC4"></a>;; <b>CHKS3</b>
+L0EC4:  ADD     A,(HL)
+        INC     HL
+        DJNZ    <A href="#L0EC4">L0EC4</a>           ; back to CHKS3
+        CP      (HL)
+        RET     NZ
+        LD      A,($5CCE)       ; sv NTDEST
+        AND     A
+        JR      Z,<A href="#L0EDD">L0EDD</a>         ; forward to BRCAST
+        CP      (IX+$0C)        ; NCSELF
+        RET     NZ
+        LD      A,($5CCF)       ; sv NTSRCE
+        CP      (IX+$0B)        ; NCIRIS
+        RET     NZ
+        JR      <A href="#L0EE2">L0EE2</a>           ; forward to TEST-BLKN
+; ---
+<a name="L0EDD"></a>;; <b>BRCAST</b>
+L0EDD:  LD      A,(IX+$0B)      ; NCIRIS
+        OR      A
+        RET     NZ
+<a name="L0EE2"></a>;; <b>TEST-BLKN</b>
+L0EE2:  LD      HL,($5CD0)      ; sv NTNUMB
+        LD      E,(IX+$0D)      ; NCNUMB_lo
+        LD      D,(IX+$0E)      ; NCNUMB_hi
+        AND     A
+        SBC     HL,DE
+        JR      Z,<A href="#L0F02">L0F02</a>         ; forward to GET-NBUFF
+        DEC     HL
+        LD      A,H
+        OR      L
+        RET     NZ
+;   <font color=#9900FF>Note.</font> The return status of the next routine should really be checked.
+        CALL    <A href="#L0F02">L0F02</a>           ; routine GET-NBUFF
+;   <font color=#9900FF>Note.</font> The DEC instruction does not affect the carry flag.
+        DEC     (IX+$0D)        ; NCNUMB_lo
+        JR      NC,<A href="#L0EFF">L0EFF</a>        ; forward, with no carry, to GETNB-END !!
+        DEC     (IX+$0E)        ; NCNUMB_hi
+<a name="L0EFF"></a>;; <b>GETNB-END</b>
+L0EFF:  OR      $01
+        RET
+<a name="L0F02"></a>;; <b>GET-NBUFF</b>
+L0F02:  LD      A,($5CCE)       ; sv NTDEST
+        OR      A
+        CALL    NZ,<A href="#L107B">L107B</a>        ; routine SEND-RESP
+        LD      A,($5CD3)       ; sv NTLEN
+        AND     A
+        JR      Z,<A href="#L0F30">L0F30</a>         ; forward to STORE-LEN
+        PUSH    IX
+        POP     HL
+        LD      DE,$0015
+        ADD     HL,DE
+        PUSH    HL
+        LD      E,A
+        CALL    <A href="#L104F">L104F</a>           ; routine INPAK
+        POP     HL
+        RET     NZ
+        LD      A,($5CD3)       ; sv NTLEN
+        LD      B,A
+        LD      A,($5CD4)       ; sv NTDCS
+<a name="L0F24"></a>;; <b>CHKS4</b>
+L0F24:  SUB     (HL)
+        INC     HL
+        DJNZ    <A href="#L0F24">L0F24</a>           ; back to CHKS4
+        RET     NZ
+        LD      A,($5CCE)       ; sv NTDEST
+        AND     A
+        CALL    NZ,<A href="#L107B">L107B</a>        ; routine SEND-RESP
+<a name="L0F30"></a>;; <b>STORE-LEN</b>
+L0F30:  LD      A,($5CD3)       ; sv NTLEN
+        LD      (IX+$14),A      ; NCIBL
+        INC     (IX+$0D)        ; NCNUMB_lo
+        JR      NZ,<A href="#L0F3E">L0F3E</a>        ; forward to GETBF-END
+        INC     (IX+$0E)        ; NCNUMB_hi
+<a name="L0F3E"></a>;; <b>GETBF-END</b>
+L0F3E:  CP      A
+        RET
+; --------------------------------------
+; THE <b><font color=#333388>'OPEN "N" CHANNEL COMMAND'</font></b> ROUTINE
+; --------------------------------------
+;
+<a name="L0F40"></a>;; <b>OPEN-N-ST</b>
+L0F40:  CALL    <A href="#L0F52">L0F52</a>           ; routine OP-PERM-N
+        JP      <A href="#L0B51">L0B51</a>           ; jump to OP-STREAM
+; ----------------------------------------
+; THE <b><font color=#333388>'OPEN TEMPORARY "N" CHANNEL'</font></b> ROUTINE
+; ----------------------------------------
+; <font color=#339933>(Hook Code: $2D)</font>
+;
+<a name="L0F46"></a>;; <b>OP-TEMP-N</b>
+L0F46:  CALL    <A href="#L0F52">L0F52</a>           ; routine OP-PERM-N
+        LD      IX,($5C51)      ; sv CURCHL
+        SET     7,(IX+$04)      ; channel letter
+        RET
+; ----------------------------------------
+; THE <b><font color=#333388>'OPEN PERMANENT "N" CHANNEL'</font></b> ROUTINE
+; ----------------------------------------
+;
+<a name="L0F52"></a>;; <b>OP-PERM-N</b>
+L0F52:  LD      HL,($5C53)      ; sv PROG
+        DEC     HL
+        LD      BC,$0114
+        PUSH    BC
+        PUSH    HL
+        PUSH    BC
+        LD      HL,($5C65)      ; sv STKEND
+        ADD     HL,BC
+        JP      C,<A href="#L0F9E">L0F9E</a>         ; jump to OUTMEM
+        LD      BC,$0050
+        ADD     HL,BC
+        JP      C,<A href="#L0F9E">L0F9E</a>         ; jump to OUTMEM
+        SBC     HL,SP
+        JP      NC,<A href="#L0F9E">L0F9E</a>        ; jump to OUTMEM
+        POP     BC
+        POP     HL
+        RST     10H             ; CALBAS
+        DEFW    $1655           ; main MAKE-ROOM
+        INC     HL
+        POP     BC
+        CALL    <A href="#L1A82">L1A82</a>           ; routine REST-N-AD
+        LD      ($5C51),HL      ; sv CURCHL
+        EX      DE,HL           ;
+        LD      HL,<A href="#L0FA3">L0FA3</a>        ; NCHAN-DAT
+        LD      BC,$000B        ; eleven bytes.
+        LDIR                    ;
+        LD      A,($5CD6)       ; sv D_STR1 drive number
+        LD      (DE),A
+        INC     DE
+        LD      A,($5CC5)       ; sv NTSTAT
+        LD      (DE),A
+        INC     DE
+        XOR     A
+        LD      (DE),A
+        LD      H,D
+        LD      L,E
+        INC     DE
+        LD      BC,$0106
+        LDIR
+        LD      DE,($5C51)      ; sv CURCHL
+        RET
+; ---
+<a name="L0F9E"></a>;; <b>OUTMEM</b>
+L0F9E:  LD      (IY+$00),$03    ; sv ERR_NR
+        RST     28H             ; Error Main ROM
+; ------------------------------
+; THE <b><font color=#333388>'"N" CHANNEL DATA'</font></b> ROUTINE
+; ------------------------------
+;
+<a name="L0FA3"></a>;; <b>NCHAN_DAT</b>
+L0FA3:  DEFW    $0008           ; main ERROR-1
+        DEFW    $0008           ; main ERROR-1
+        DEFB    $4E             ; character "N"
+        DEFW    <A href="#L0E09">L0E09</a>           ; NCHAN-OUT
+        DEFW    <A href="#L0DA9">L0DA9</a>           ; N-INPUT
+        DEFW    $0114           ; length
+; ---------------------------------------
+; THE <b><font color=#333388>'SEND EOF BLOCK TO NETWORK'</font></b> ROUTINE
+; ---------------------------------------
+;
+<a name="L0FAE"></a>;; <b>SEND-NEOF</b>
+L0FAE:  LD      IX,($5C51)      ; sv CURCHL
+        LD      A,(IX+$10)      ; NCOBL
+        AND     A               ;
+        RET     Z               ;
+        LD      A,$01           ;
+        JP      <A href="#L0E48">L0E48</a>           ; jump to S-PACK-1
+; ---------------------------
+; THE <b><font color=#333388>'NETWORK STATE'</font></b> ROUTINE
+; ---------------------------
+;
+<a name="L0FBC"></a>;; <b>NET-STATE</b>
+L0FBC:  LD      A,R             ;
+        OR      $C0             ;
+        LD      B,A             ;
+        CALL    <A href="#L0FC7">L0FC7</a>           ; routine CHK-REST
+        JR      C,<A href="#L0FBC">L0FBC</a>         ; back to NET-STATE
+        RET                     ;
+; ---------------------------
+; THE <b><font color=#333388>'CHECK-RESTING'</font></b> ROUTINE
+; ---------------------------
+;
+<a name="L0FC7"></a>;; <b>CHK-REST</b>
+L0FC7:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+<a name="L0FCA"></a>;; <b>MAKESURE</b>
+L0FCA:  PUSH    BC              ;
+        POP     BC              ;
+        IN      A,($F7)         ;
+        RRCA                    ;
+        RET     C               ;
+        DJNZ    <A href="#L0FCA">L0FCA</a>           ; back to MAKESURE
+        RET                     ;
+; ------------------------
+; THE <b><font color=#333388>'WAIT-SCOUT'</font></b> ROUTINE
+; ------------------------
+;
+<a name="L0FD3"></a>;; <b>WT-SC-E</b>
+L0FD3:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+        LD      HL,$01C2        ;
+<a name="L0FD9"></a>;; <b>CLAIMED</b>
+L0FD9:  LD      B,$80           ;
+        CALL    <A href="#L0FC7">L0FC7</a>           ; routine CHK-REST
+        JR      NC,<A href="#L0FED">L0FED</a>        ; forward to WT-SYNC
+        DEC     HL              ;
+        DEC     HL              ;
+        LD      A,H             ;
+        OR      L               ;
+        JR      NZ,<A href="#L0FD9">L0FD9</a>        ; back to CLAIMED
+        LD      A,(IX+$0B)      ; NCIRIS
+        AND     A               ;
+        JR      Z,<A href="#L0FD9">L0FD9</a>         ; back to CLAIMED
+        RET                     ;
+<a name="L0FED"></a>;; <b>WT-SYNC</b>
+L0FED:  IN      A,($F7)         ;
+        RRCA                    ;
+        JR      C,<A href="#L1013">L1013</a>         ; forward to SCOUT-END
+        LD      A,$7F           ;
+        IN      A,($FE)         ;
+        OR      $FE             ;
+        IN      A,($FE)         ;
+        RRA                     ;
+        CALL    NC,<A href="#L163E">L163E</a>        ; routine TEST-BRK
+        DEC     HL              ;
+        LD      A,H             ;
+        OR      L               ;
+        JR      NZ,<A href="#L0FED">L0FED</a>        ; back to WT-SYNC
+        LD      A,(IX+$0B)      ; NCIRIS
+        AND     A               ;
+        JR      Z,<A href="#L0FED">L0FED</a>         ; back to WT-SYNC
+        RET                     ;
+; --------------------------------------
+; THE <b><font color=#333388>'BREAK INTO I/O OPERATION'</font></b> ROUTINE
+; --------------------------------------
+; <font color=#9900FF>Note.</font> an obsolete duplicate.
+<a name="L100A"></a>;; <b>E-READ-N</b>
+L100A:  EI                      ;
+        CALL    <A href="#L0D4D">L0D4D</a>           ; routine BORD-REST
+        LD      (IY+$00),$14    ; sv ERR_NR
+        RST     28H             ; Error Main ROM
+; ----------------------
+; THE <b><font color=#333388>'SCOUT END'</font></b> BRANCH
+; ----------------------
+;
+<a name="L1013"></a>;; <b>SCOUT-END</b>
+L1013:  LD      L,$09
+<a name="L1015"></a>;; <b>LP-SCOUT</b>
+L1015:  DEC     L
+        SCF
+        RET     Z
+        LD      B,$0E
+<a name="L101A"></a>;; <b>DELAY-SC</b>
+L101A:  DJNZ    <A href="#L101A">L101A</a>           ; back to DELAY-SC
+        JR      <A href="#L1015">L1015</a>           ; back to LP-SCOUT
+; ------------------------
+; THE <b><font color=#333388>'SEND-SCOUT'</font></b> ROUTINE
+; ------------------------
+;
+<a name="L101E"></a>;; <b>SEND-SC</b>
+L101E:  CALL    <A href="#L0FBC">L0FBC</a>           ; routine NET-STATE
+        LD      C,$F7
+        LD      HL,$0009
+        LD      A,($5CC5)       ; sv NTSTAT
+        LD      E,A
+        IN      A,($F7)
+        RRCA
+        JR      C,<A href="#L101E">L101E</a>         ; back to SEND-SC
+<a name="L102F"></a>;; <b>ALL-BITS</b>
+L102F:  OUT     (C),H
+        LD      D,H
+        LD      H,$00
+        RLC     E
+        RL      H
+        LD      B,$08
+<a name="L103A"></a>;; <b>S-SC-DEL</b>
+L103A:  DJNZ    <A href="#L103A">L103A</a>           ; back to S-SC-DEL
+        IN      A,($F7)
+        AND     $01
+        CP      D
+        JR      Z,<A href="#L101E">L101E</a>         ; back to SEND-SC
+        DEC     L
+        JR      NZ,<A href="#L102F">L102F</a>        ; back to ALL-BITS
+        LD      A,$01
+        OUT     ($F7),A
+        LD      B,$0E
+<a name="L104C"></a>;; <b>END-S-DEL</b>
+L104C:  DJNZ    <A href="#L104C">L104C</a>           ; back to END-S-DEL
+        RET
+; -------------------
+; THE <b><font color=#333388>'INPAK'</font></b> ROUTINE
+; -------------------
+;
+<a name="L104F"></a>;; <b>INPAK</b>
+L104F:  LD      B,$FF
+<a name="L1051"></a>;; <b>N-ACTIVE</b>
+L1051:  IN      A,($F7)
+        RRA
+        JR      C,<A href="#L105A">L105A</a>         ; forward to INPAK-2
+        DJNZ    <A href="#L1051">L1051</a>           ; back to N-ACTIVE
+        INC     B
+        RET
+; ---
+<a name="L105A"></a>;; <b>INPAK-2</b>
+L105A:  LD      B,E
+<a name="L105B"></a>;; <b>INPAK-L</b>
+L105B:  LD      E,$80
+        LD      A,$CE
+        OUT     ($EF),A
+        NOP
+        NOP
+        INC     IX
+        DEC     IX
+        INC     IX
+        DEC     IX
+<a name="L106B"></a>;; <b>UNTIL-MK</b>
+L106B:  LD      A,$00
+        IN      A,($F7)
+        RRA
+        RR      E
+        JP      NC,<A href="#L106B">L106B</a>        ; jump to UNTIL-MK
+        LD      (HL),E
+        INC     HL
+        DJNZ    <A href="#L105B">L105B</a>           ; back to INPAK-L
+        CP      A
+        RET
+; --------------------------------
+; THE <b><font color=#333388>'SEND RESPONSE BYTE'</font></b> ROUTINE
+; --------------------------------
+;
+<a name="L107B"></a>;; <b>SEND-RESP</b>
+L107B:  LD      A,$01
+        LD      HL,$5CCD        ; sv NTRESP
+        LD      (HL),A
+        LD      E,A
+; --------------------
+; THE <b><font color=#333388>'OUTPAK'</font></b> ROUTINE
+; --------------------
+;
+<a name="L1082"></a>;; <b>OUTPAK</b>
+L1082:  XOR     A
+        OUT     ($F7),A
+        LD      B,$04
+<a name="L1087"></a>;; <b>DEL-0-1</b>
+L1087:  DJNZ    <A href="#L1087">L1087</a>           ; back to DEL-0-1
+<a name="L1089"></a>;; <b>OUTPAK-L</b>
+L1089:  LD      A,(HL)
+        CPL
+        SCF
+        RLA
+        LD      B,$0A
+<a name="L108F"></a>;; <b>UNT-MARK</b>
+L108F:  OUT     ($F7),A
+        RRA
+        AND     A
+        DEC     B
+        LD      D,$00
+        JP      NZ,<A href="#L108F">L108F</a>        ; jump to UNT-MARK
+        INC     HL
+        DEC     E
+        PUSH    HL
+        POP     HL
+        JP      NZ,<A href="#L1089">L1089</a>        ; jump to OUTPAK-L
+        LD      A,$01
+        OUT     ($F7),A
+        RET
+; *****************************************************
+; **  T H E   M I C R O D R I V E   R O U T I N E S  **
+; *****************************************************
+; The shadow ROM uses the alternate HL register solely in connection with the
+; microdrive maps. This does not conflict with the Main ROM use in the
+; calculator.  When used as a Hook Codes, then the calculator is implicitly in
+; use by the user and so HL' should be preserved throughout.
+; -----------------------------------------
+; THE <b><font color=#333388>'SET A TEMPORARY "M" CHANNEL'</font></b> ROUTINE
+; -----------------------------------------
+; <font color=#339933>(Hook Code: $2B)</font>
+; This routine is used to create all microdrive channels. The routine that
+; creates a permanent channel (as used by a print file) uses this routine and
+; then converts the temporary channel to a permanent one.
+; Temporary channels are created by LOAD, SAVE, CAT etc. and last just as long
+; as required. They are deleted before returning to the Main ROM by the next
+; routine DEL-M-BUF.
+<a name="L10A5"></a>;; <b>SET-T-MCH</b>
+L10A5:  EXX                     ; exx
+        LD      HL,$0000        ; set HL' to zero as the default no-map-exists
+                                ; condition.
+        EXX                     ; exx
+        LD      IX,($5C4F)      ; set IX from system variable CHANS.
+        LD      DE,$0014        ; skip over the twenty bytes of the standard
+        ADD     IX,DE           ; channels to point to the next or end-marker.
+; now enter a search of existing "M" channels to see if any use the same drive.
+<a name="L10B3"></a>;; <b>CHK-LOOP</b>
+L10B3:  LD      A,(IX+$00)      ; fetch the next byte.
+        CP      $80             ; compare to end-marker.
+        JR      Z,<A href="#L10F1">L10F1</a>         ; forward, if so, to CHAN-SPC.
+        LD      A,(IX+$04)      ; fetch the letter of the extended channel.
+        AND     $7F             ; reset bit 7.
+        CP      $4D             ; is it character 'M' ?
+        JR      NZ,<A href="#L10E7">L10E7</a>        ; forward, if not, to NEXT-CHAN.
+; an existing Microdrive Channel has been found.
+        LD      A,($5CD6)       ; fetch drive number from system variable D_STR1
+        CP      (IX+$19)        ; compare to CHDRIV the drive associated with
+                                ; this channel.
+        JR      NZ,<A href="#L10E7">L10E7</a>        ; forward, if not the same, to NEXT-CHAN.
+; a Microdrive Channel has been found that matches the current drive.
+; It will not be necessary to create a new map for the temporary channel.
+        EXX                     ; -
+        LD      L,(IX+$1A)      ; load address of the associated microdrive.
+        LD      H,(IX+$1B)      ; map into the HL' register.
+        EXX                     ; -
+        LD      BC,($5CDA)      ; load BC with length of filename from N_STR1.
+        LD      HL,($5CDC)      ; load HL with address of filename.
+        CALL    <A href="#L1403">L1403</a>           ; routine CHK-NAME checks name in channel
+                                ; against name addressed by HL.
+        JR      NZ,<A href="#L10E7">L10E7</a>        ; forward, with name mismatch, to NEXT-CHAN.
+        BIT     0,(IX+$18)      ; test CHFLAG.
+        JR      Z,<A href="#L10E7">L10E7</a>         ; forward to NEXT-CHAN.
+        RST     20H             ; Shadow Error Restart.
+        DEFB    $0D             ; Reading a 'write' file.
+<a name="L10E7"></a>;; <b>NEXT-CHAN</b>
+L10E7:  LD      E,(IX+$09)      ; fetch length of channel.
+        LD      D,(IX+$0A)      ; to the DE register pair.
+        ADD     IX,DE           ; add to point to the following location.
+        JR      <A href="#L10B3">L10B3</a>           ; loop back to CHK-LOOP until end-marker found.
+; ---
+; Now create the space for the channel.
+<a name="L10F1"></a>;; <b>CHAN-SPC</b>
+L10F1:  LD      HL,($5C53)      ; set pointer from system variable PROG.
+        DEC     HL              ; now points to channels end-marker (as does IX)
+        PUSH    HL              ; * save a copy of new location.
+        LD      BC,$0253        ; set amount of bytes required.
+;   <font color=#9900FF>Note.</font> interrupts are disabled so on the original shadow ROM, which launched
+;   straight into the MAKE-ROOM routine, the system hung if there was
+;   insufficient free memory, at the HALT instruction in the Main error report.
+;   The solution here is to perform the same checks that will be performed by
+;   the Main MAKE-ROOM routine.
+        PUSH    HL              ; save first location
+        PUSH    BC              ; and amount while free memory is checked.
+        LD      HL,($5C65)      ; fetch start of free memory from STKEND
+        ADD     HL,BC           ; add bytes required producing carry if
+                                ; result is higher than 65535
+        JP      C,<A href="#L119A">L119A</a>         ; jump, if so, to OUTMEM2
+        LD      BC,$0050        ; now allow for overhead of eighty bytes.
+        ADD     HL,BC           ; and perform same test.
+        JP      C,<A href="#L119A">L119A</a>         ; jump, if too high, to OUTMEM2
+        SBC     HL,SP           ; finally test that result is less than the
+                                ; stack pointer at the other side of free memory.
+        JP      NC,<A href="#L119A">L119A</a>        ; jump, if higher, to OUTMEM2.
+        POP     BC              ; restore the new room
+        POP     HL              ; parameters.
+; now call the MAKE-ROOM routine in the certain knowledge that nothing can
+; go wrong.
+        RST     10H             ; CALBAS
+        DEFW    $1655           ; main MAKE-ROOM
+        POP     DE              ; * restore pointer to first new location.
+        PUSH    DE              ; * and save on machine stack again.
+        LD      HL,<A href="#L14B1">L14B1</a>        ; the default "M" CHANNEL DATA.
+        LD      BC,$0019        ; twenty five bytes to copy including blank
+        LDIR                    ; filename to start of new channel.
+        LD      A,($5CD6)       ; fetch drive number from D_STR1.
+        LD      (IX+$19),A      ; insert at CHDRIV.
+        LD      BC,$0253        ; set BC to amount of room that was created.
+        PUSH    IX              ; move start of channel
+        POP     HL              ; to HL register.
+        CALL    <A href="#L1A82">L1A82</a>           ; routine REST-N-AD corrects filename pointers
+                                ; leaving DE at first filename D_STR1.
+        EX      DE,HL           ; transfer filename pointer to HL.
+        LD      BC,($5CDA)      ; set BC to length of filename from N_STR1.
+        BIT     7,B             ; test for the default $FF bytes.
+        JR      NZ,<A href="#L1143">L1143</a>        ; forward, with no name, to TEST-MAP
+; now enter a loop to transfer the filename to CHNAME, counting BC down to zero.
+; The filename could be in ROM with <b><font color=#333388>'run'</font></b> or more usually in string workspace
+; with its parameters on the calculator stack as with
+; LOAD * "m";1;"crapgame"
+; SAVE * "M";7; CHR$0 + "secret".
+<a name="L1135"></a>;; <b>T-CH-NAME</b>
+L1135:  LD      A,B             ; check length
+        OR      C               ; for zero.
+        JR      Z,<A href="#L1143">L1143</a>         ; forward, if so, to TEST-MAP.
+        LD      A,(HL)          ; fetch character of filename.
+        LD      (IX+$0E),A      ; transfer to same position in CHNAME.
+        INC     HL              ; increment
+        INC     IX              ; both pointers.
+        DEC     BC              ; decrement length.
+        JR      <A href="#L1135">L1135</a>           ; loop back to T-CH-NAME.
+; ---
+<a name="L1143"></a>;; <b>TEST-MAP</b>
+L1143:  POP     IX              ; * restore pointer to first location of channel.
+        EXX                     ; exchange set - no need now to keep balanced.
+        LD      A,H             ; test map address for zero .
+        OR      L               ; indicating that this drive has no map.
+        JR      NZ,<A href="#L1168">L1168</a>        ; forward, if map exists, to ST-MAP-AD.
+; a microdrive map is now created for this drive.
+        LD      HL,($5C4F)      ; set pointer from system variable CHANS.
+        PUSH    HL              ; save this pointer to the new area.
+        DEC     HL              ; set HL to location before new room.
+        LD      BC,$0020        ; thirty two bytes are required.
+        RST     10H             ; CALBAS
+        DEFW    $1655           ; main MAKE-ROOM.
+; now handle dynamic pointers outside the control of the Main ROM
+        POP     HL              ; restore pointer to first location.
+        LD      BC,$0020        ; thirty two bytes were created.
+        ADD     IX,BC           ; channel was moved up so adjust that pointer.
+        CALL    <A href="#L1A82">L1A82</a>           ; routine REST-N-AD corrects filename pointers.
+; fill map with $FF bytes
+        LD      A,$FF           ; the fill byte.
+        LD      B,$20           ; thirty two locations.
+        PUSH    HL              ; save map address pointer.
+<a name="L1163"></a>;; <b>FILL-MAP</b>
+L1163:  LD      (HL),A          ; insert the byte
+        INC     HL              ; next location.
+        DJNZ    <A href="#L1163">L1163</a>           ; loop back to FILL-MAP
+        POP     HL              ; restore address.
+<a name="L1168"></a>;; <b>ST-MAP-AD</b>
+L1168:  LD      (IX+$1A),L      ; place map address in
+        LD      (IX+$1B),H      ; channel at CHMAP.
+; now make DE point to IX+$19 the header preamble and copy ROM preamble bytes.
+        PUSH    IX              ; push start of channel
+        POP     HL              ; pop to HL
+        LD      DE,$001C        ; the offset is $1C
+        ADD     HL,DE           ; add to point to start of header preamble.
+        EX      DE,HL           ; transfer this destination to DE.
+        LD      HL,<A href="#L14CA">L14CA</a>        ; point HL to PREAMBLE data in this ROM.
+        LD      BC,$000C        ; twelve bytes to copy to channel.
+        LDIR                    ; in they go.
+; now use the same technique to copy the same 12 bytes of ROM preamble
+; to IX+$37, the data block preamble in the channel.
+; A little long-winded as the destination only requires adjustment.
+        PUSH    IX              ;
+        POP     HL              ;
+        LD      DE,$0037        ;
+        LD      BC,$000C        ;
+        ADD     HL,DE           ;
+        EX      DE,HL           ;
+        LD      HL,<A href="#L14CA">L14CA</a>        ; the PREAMBLE data.
+        LDIR                    ;
+; now form the offset from CHANS to this channel for a return value to be
+; inserted in the STRMS area.
+        PUSH    IX              ; transfer
+        POP     HL              ; pointer.
+        LD      DE,($5C4F)      ; fetch start of CHANS area from CHANS
+        OR      A               ; clear carry for subtraction.
+        SBC     HL,DE           ; the true offset.
+        INC     HL              ; add one as the offset is to second location.
+        RET                     ; return.               &gt;&gt;&gt;
+; ---
+<a name="L119A"></a>;; <b>OUTMEM2</b>
+L119A:  LD      (IY+$00),$03    ; set ERR_NR for '4 Out of memory'
+        RST     28H             ; Error Main ROM
+; ---------------------------------
+; THE <b><font color=#333388>'RECLAIM "M" CHANNEL'</font></b> ROUTINE
+; ---------------------------------
+; <font color=#339933>(Hook Code: $2C)</font>
+; This routine is used to reclaim a temporary "M" channel such as that created
+; by the routine above and to reclaim a permanent "M" channel by the CLOSE
+; command routines.
+<a name="L119F"></a>;; <b>DEL-M-BUF</b>
+L119F:  LD      L,(IX+$1A)      ; fetch map address.
+        LD      H,(IX+$1B)      ; from CHMAP.
+        PUSH    HL              ; and save.
+        LD      A,(IX+$19)      ; fetch drive number from CHDRIV.
+        PUSH    AF              ; and save also.
+        PUSH    IX              ; transfer channel base address
+        POP     HL              ; to the HL register pair.
+        LD      BC,$0253        ; set BC to bytes to reclaim.
+        RST     10H             ; CALBAS
+        DEFW    $19E8           ; main RECLAIM-2 reclaims the channel.
+        PUSH    IX              ; transfer channel
+        POP     HL              ; base address again.
+        LD      DE,($5C4F)      ; set DE to start of channels from CHANS
+        OR      A               ; clear carry.
+        SBC     HL,DE           ; subtract to form the offset.
+        INC     HL              ; add 1 as points to second byte.
+        LD      BC,$0253        ; set the number of bytes reclaimed.
+        CALL    <A href="#L1444">L1444</a>           ; routine REST-STRM corrects all stream offsets
+                                ; in the standard systems variables area
+                                ; reducing them if they followed the deleted
+                                ; channel.
+        POP     AF              ; restore drive number
+        POP     HL              ; and old map address.
+; now consider deleting the map if it was used only by the reclaimed channel.
+        LD      B,A             ; transfer drive to B
+        LD      IX,($5C4F)      ; set IX from CHANS
+        LD      DE,$0014        ; prepare to step over the twenty standard bytes
+        ADD     IX,DE           ; to address next channel or end-marker.
+<a name="L11D0"></a>;; <b>TEST-MCHL</b>
+L11D0:  LD      A,(IX+$00)      ; fetch current byte.
+        CP      $80             ; compare to end-marker.
+        JR      Z,<A href="#L11EF">L11EF</a>         ; forward, with match, to RCLM-MAP
+        LD      A,(IX+$04)      ; fetch the channel letter.
+        AND     $7F             ; cancel any inverted bit.
+        CP      $4D             ; is character "M" ?
+        JR      NZ,<A href="#L11E5">L11E5</a>        ; forward, if not, to NXTCHAN
+        LD      A,(IX+$19)      ; fetch this channel drive number.
+        CP      B               ; compare to that of deleted channel.
+        RET     Z               ; return with match - the microdrive map is
+                                ; still in use.                              &gt;&gt;
+; else continue search.
+<a name="L11E5"></a>;; <b>NXTCHAN</b>
+L11E5:  LD      E,(IX+$09)      ; fetch length of channel
+        LD      D,(IX+$0A)      ; to DE register.
+        ADD     IX,DE           ; add to address next channel.
+        JR      <A href="#L11D0">L11D0</a>           ; loop back to TEST-MCHL
+; ---
+; the branch was here when the end-marker was encountered without finding a
+; channel that uses the map.
+<a name="L11EF"></a>;; <b>RCLM-MAP</b>
+L11EF:  LD      BC,$0020        ; thirty two bytes to reclaim.
+        PUSH    HL              ; save pointer to start.
+        PUSH    BC              ; save the 32 bytes.
+        RST     10H             ; CALBAS
+        DEFW    $19E8           ; main RECLAIM-2 reclaims the microdrive map.
+        POP     BC              ; restore 32 counter.
+        POP     HL              ; restore map address.
+        CALL    <A href="#L1476">L1476</a>           ; routine REST-MAP adjusts all channel map
+                                ; addresses.
+        RET                     ; return.
+; -------------------------------
+; THE <b><font color=#333388>'"M" CHANNEL INPUT'</font></b> ROUTINE
+; -------------------------------
+;
+<a name="L11FD"></a>;; <b>M-INPUT</b>
+L11FD:  LD      IX,($5C51)      ; sv CURCHL
+        LD      HL,<A href="#L1207">L1207</a>        ; addr: MCHAN-IN
+        JP      <A href="#L0D5A">L0D5A</a>           ; jump to CALL-INP
+; ---------------------------------------
+; THE <b><font color=#333388>'"M" CHANNEL INPUT SERVICE'</font></b> ROUTINE
+; ---------------------------------------
+;
+<a name="L1207"></a>;; <b>MCHAN-IN</b>
+L1207:  BIT     0,(IX+$18)      ; test CHFLAG
+        JR      Z,<A href="#L120F">L120F</a>         ; forward, if reset, to TEST-M-BF
+<a name="L120D"></a>;; <b>rwf-err</b>
+L120D:  RST     20H             ; Shadow Error Restart
+        DEFB    $0D             ; Reading a 'write' file
+; ---
+<a name="L120F"></a>;; <b>TEST-M-BF</b>
+L120F:  LD      E,(IX+$0B)      ; load DE with the offset from CHDATA of the
+        LD      D,(IX+$0C)      ; next byte to be received from CHBYTE.
+        LD      L,(IX+$45)      ; load HL with the number of data bytes
+        LD      H,(IX+$46)      ; in CHDATA from RECLEN.
+        SCF                     ; set carry to include
+        SBC     HL,DE           ; subtract the two relative positions.
+        JR      C,<A href="#L1233">L1233</a>         ; forward to CHK-M-EOF
+        INC     DE              ; else increment pointer.
+        LD      (IX+$0B),E      ; store back
+        LD      (IX+$0C),D      ; in CHBYTE.
+        DEC     DE              ; decrement pointer.
+        PUSH    IX              ; save start of channel.
+        ADD     IX,DE           ; add the offset within CHDATA first.
+        LD      A,(IX+$52)      ; now apply offset of CHDATA from start of
+                                ; channel to character.
+        POP     IX              ; restore channel start.
+        SCF                     ; set carry flag.
+        RET                     ; return.
+; ---
+<a name="L1233"></a>;; <b>CHK-M-EOF</b>
+L1233:  BIT     1,(IX+$43)      ; bit 1 of RECFLG is set if this is the last
+                                ; record in this file.
+        JR      Z,<A href="#L123D">L123D</a>         ; forward, if not EOF, to NEW-BUFF.
+        XOR     A               ; set accumulator to zero.
+        ADD     A,$0D           ; add to carriage return clearing the
+                                ; carry flag and resetting the zero flag.
+        RET                     ; return.
+; ---
+<a name="L123D"></a>;; <b>NEW-BUFF</b>
+L123D:  LD      DE,$0000        ; set next byte offset to zero.
+        LD      (IX+$0B),E      ; and update the
+        LD      (IX+$0C),D      ; pointer CHBYTE.
+        INC     (IX+$0D)        ; increment record number CHREC.
+        CALL    <A href="#L1252">L1252</a>           ; routine GET-RECD gets the record specified
+                                ; by CHREQ matching filename CHNAME from the
+                                ; cartridge in the drive CHDRIV which is
+                                ; started.
+        XOR     A               ; signal stop all motors.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE.
+        JR      <A href="#L120F">L120F</a>           ; back to TEST-M-BF.
+; --------------------------
+; THE <b><font color=#333388>'GET A RECORD'</font></b> ROUTINE
+; --------------------------
+;   This routine is used to read a specific record from a PRINT type file.
+;   It is called twice -
+;   1) From the "M" input routine when the current record is exhausted and the
+;      next record is to be read in.
+;   2) From Hook Code $27 READ-RANDOM.
+<a name="L1252"></a>;; <b>GET-RECD</b>
+L1252:  LD      A,(IX+$19)      ; get drive number from CHDRIV.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE starts the motor.
+; -&gt;
+<a name="L1258"></a>;; <b>GET-R-2</b>
+L1258:  LD      BC,$04FB        ; set sector counter to 1275 = 255*5
+        LD      ($5CC9),BC      ; update system variable SECTOR
+<a name="L125F"></a>;; <b>GET-R-LP</b>
+L125F:  CALL    <A href="#L1280">L1280</a>           ; routine G-HD-RC reads in the next header and
+                                ; matching record to pass the tape head.
+        JR      C,<A href="#L1279">L1279</a>         ; forward, with name mismatch, to NXT-SCT
+        JR      Z,<A href="#L1279">L1279</a>         ; forward, if not in use, to NXT-SCT
+        LD      A,(IX+$44)      ; fetch the record number 0-n from RECNUM
+        CP      (IX+$0D)        ; compare with that required in CHREC
+        JR      NZ,<A href="#L1279">L1279</a>        ; forward, if no number match, to NXT-SCT
+        PUSH    IX              ; transfer address of Microdrive channel
+        POP     HL              ; from the IX to HL registers.
+        LD      DE,$0052        ; offset to CHDATA
+        ADD     HL,DE           ; add to form address of start of 512 byte data
+        CALL    <A href="#L142B">L142B</a>           ; routine CHKS-BUFF
+        RET     Z               ; return if checksums match.
+<a name="L1279"></a>;; <b>NXT-SCT</b>
+L1279:  CALL    <A href="#L13F7">L13F7</a>           ; routine DEC-SECT
+        JR      NZ,<A href="#L125F">L125F</a>        ; loop back, if not zero, to GET-R-LP
+; else produce the Error Report.
+        RST     20H             ; Shadow Error Restart
+        DEFB    $11             ; File not found
+; ---------------------------------------
+; THE <b><font color=#333388>'GET HEADER AND DATA BLOCK'</font></b> ROUTINE
+; ---------------------------------------
+; This routine fetches at random a header and matching record and sets the
+; flags to indicate three possible outcomes.
+;
+; Zero flag set - record is not in use.
+; Carry flag set - name does not match required
+; Both flags reset - the name matches required.
+<a name="L1280"></a>;; <b>G-HD-RC</b>
+L1280:  CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads in and checksums
+                                ; the next 14 byte header to pass tape heads.
+        LD      DE,$001B        ; prepare the offset from header to RECFLG and
+        ADD     HL,DE           ; add to address the start of 528 byte RECORD
+        CALL    <A href="#L15EB">L15EB</a>           ; routine GET-M-BUF reads in the record
+                                ; descriptor and data.
+                                ; register HL addresses RECFLG
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R checksums the 14 bytes
+                                ; of the record descriptor.
+        JR      NZ,<A href="#L12B1">L12B1</a>        ; forward, with error, to G-REC-ERR
+        BIT     0,(IX+$43)      ; check RECFLG - should be reset.
+        JR      NZ,<A href="#L12B1">L12B1</a>        ; forward, if not, to G-REC-ERR
+; now test descriptor for an unused record.
+        LD      A,(IX+$43)      ; load A with RECFLG - bit 1 indicates EOF
+        OR      (IX+$46)        ; combine with RECLEN_hi bit 1 set if full.
+        AND     $02             ; test for either full record or EOF.
+        RET     Z               ; return if not with zero set and carry reset
+                                ; signaling that record is unused.
+; the record is a contender for a header record.
+        PUSH    IX              ; transfer start of channel
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0047        ; offset to 10 characters of filename.
+        ADD     HL,DE           ; add so HL addresses the start of RECNAM.
+        LD      BC,$000A        ; ten bytes to compare against required CHNAME.
+        CALL    <A href="#L1403">L1403</a>           ; routine CHK-NAME
+        JR      NZ,<A href="#L12B1">L12B1</a>        ; forward, with name mismatch, to G-REC-ERR
+; else set flags to signal success before returning.
+        LD      A,$FF           ; prepare to reset zero flag
+        OR      A               ; also reset carry
+        RET                     ; return with zero reset and carry reset.
+; ---
+; else set carry to signal names do not match.
+<a name="L12B1"></a>;; <b>G-REC-ERR</b>
+L12B1:  SCF                     ; set carry flag to signal failure and
+                                ; instigate another search.
+        RET                     ; return with zero reset and carry set.
+; --------------------------------
+; THE <b><font color=#333388>'"M" CHANNEL OUTPUT'</font></b> ROUTINE
+; --------------------------------
+; labeled MWRCH in source code.
+<a name="L12B3"></a>;; <b>MCHAN-OUT</b>
+L12B3:  LD      IX,$FFFA
+        ADD     IX,DE
+        BIT     0,(IX+$18)      ; ???? CHFLAG
+        JR      NZ,<A href="#L12C1">L12C1</a>        ; forward to NOREAD
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0C             ; Writing to a 'read' file
+<a name="L12C1"></a>;; <b>NOREAD</b>
+L12C1:  LD      E,(IX+$0B)      ; CHBYTE
+        LD      D,(IX+$0C)      ; CHBYTE_hi
+        PUSH    IX
+        ADD     IX,DE
+        LD      (IX+$52),A      ; indexed
+        POP     IX
+        INC     DE
+        LD      (IX+$0B),E      ; CHBYTE
+        LD      (IX+$0C),D      ; CHBYTE_hi
+        BIT     1,D             ; is CHBYTE the maximum $0200 ?
+        RET     Z               ; return if not.
+; ------------------------------------------
+; THE <b><font color=#333388>'WRITE RECORD ONTO MICRODRIVE'</font></b> ROUTINE
+; ------------------------------------------
+; <font color=#339933>(Hook Code: $26)</font>
+;
+<a name="L12DA"></a>;; <b>WR-RECD</b>
+L12DA:  LD      A,(IX+$19)      ; fetch drive number.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE
+        LD      BC,$32C8        ; set BC to 13000 decimal
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC
+        CALL    <A href="#L12EE">L12EE</a>           ; routine WRITE-PRC
+        XOR     A               ; signal stop motor
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE
+        RET                     ; return.
+; -----------------------------
+; THE <b><font color=#333388>'WRITE RECORD'</font></b> SUBROUTINE
+; -----------------------------
+;
+;
+<a name="L12EE"></a>;; <b>WRITE-PRC</b>
+L12EE:  CALL    <A href="#L1349">L1349</a>           ; routine CHK-FULL.
+        JR      NZ,<A href="#L12FC">L12FC</a>        ; forward, if not, to NOFULL.
+        CALL    <A href="#L119F">L119F</a>           ; routine DEL-M-BUF reclaims the buffer.
+        XOR     A               ; set accumulator to zero.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE stops the motor.
+        RST     20H             ; Shadow Error Restart.
+        DEFB    $0F             ; 'Microdrive full'
+; ---
+<a name="L12FC"></a>;; <b>NOFULL</b>
+L12FC:  PUSH    IX              ; save the pointer to channel base.
+        LD      B,$0A           ; count ten characters.
+<a name="L1300"></a>;; <b>CP-NAME</b>
+L1300:  LD      A,(IX+$0E)      ; copy a character of CHNAME
+        LD      (IX+$47),A      ; to RECNAM
+        INC     IX              ; increment the index pointer.
+        DJNZ    <A href="#L1300">L1300</a>           ; loop back for all ten characters to CP-NAME
+        POP     IX              ; restore base of "M" channel.
+        LD      C,(IX+$0B)      ; fetch  CHBYTE_lo
+        LD      (IX+$45),C      ; update RECLEN_lo
+        LD      A,(IX+$0C)      ; fetch  CHBYTE_hi
+        LD      (IX+$46),A      ; update RECLEN_hi
+        LD      A,(IX+$0D)      ; fetch  CHREC
+        LD      (IX+$44),A      ; update RECNUM
+        RES     0,(IX+$43)      ; reset RECFLG indicating a record.
+        PUSH    IX              ; transfer channel base address
+        POP     HL              ; to the HL register.
+        LD      DE,$0043        ; prepare offset to point to RECFLG
+        ADD     HL,DE           ; and add to address the record descriptor.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R checksums the 14 bytes.
+        LD      DE,$000F        ; add extra offset to CHDATA
+        ADD     HL,DE           ; the 512 bytes of data.
+        CALL    <A href="#L142B">L142B</a>           ; routine CHKS-BUFF checksums the buffer.
+        PUSH    IX              ; <font color=#9900FF>Note.</font> this code is redundant and erroneous.
+        POP     HL              ; the three registers are set up properly
+        LD      DE,$0047        ; in the next routine.
+        CALL    <A href="#L135A">L135A</a>           ; routine SEND-BLK writes block to microdrive
+                                ; cartridge as indicated my microdrive map
+                                ; which is updated.
+; now prepare channel for next record. accumulator could be used to set CHBYTE.
+        LD      DE,$0000        ; set DE to zero.
+        LD      (IX+$0B),E      ; set CHBYTE_lo to zero
+        LD      (IX+$0C),D      ; set CHBYTE_hi to zero
+        INC     (IX+$0D)        ; increment the record counter CHREC
+        RET                     ; return.
+; ----------------------
+; THE <b><font color=#333388>'CHK-FULL'</font></b> ROUTINE
+; ----------------------
+; Check the thirty two bytes of a microdrive map for a reset bit.
+<a name="L1349"></a>;; <b>CHK-FULL</b>
+L1349:  LD      L,(IX+$1A)      ; load the address of the microdrive map
+        LD      H,(IX+$1B)      ; from CHMAP to HL.
+        LD      B,$20           ; set counter to thirty two.
+<a name="L1351"></a>;; <b>NXT-B-MAP</b>
+L1351:  LD      A,(HL)          ; fetch each byte in turn.
+        CP      $FF             ; compare to the all-full indicator.
+        RET     NZ              ; return if there is a spare sector       &gt;&gt;
+        INC     HL              ; next address.
+        DJNZ    <A href="#L1351">L1351</a>           ; loop back to NXT-B-MAP
+        XOR     A               ; set the zero flag for failure.
+        RET                     ; return.
+; ----------------------
+; THE <b><font color=#333388>'SEND-BLK'</font></b> ROUTINE
+; ----------------------
+;   This important routine is called from the FORMAT routine and the WRITE-PRC
+;   routine to write the record to the cartridge at the next available free
+;   sector as indicated by the microdrive map.
+<a name="L135A"></a>;; <b>SEND-BLK</b>
+L135A:  PUSH    IX              ; transfer the channel
+        POP     HL              ; address to HL.
+        LD      DE,$0037        ; offset to data preamble.
+        ADD     HL,DE           ; add to address using HL
+        PUSH    HL              ; save pointer to data block
+; now enter a loop to find the header of an available record on microdrive.
+; This SEND-BLK routine is only called when there is known to be a record
+; available on the tape.
+<a name="L1362"></a>;; <b>FAILED</b>
+L1362:  CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 gets any old header.
+        CALL    <A href="#L13C4">L13C4</a>           ; routine CHECK-MAP checks if sector is free
+                                ; on the microdrive map.
+        JR      NZ,<A href="#L1362">L1362</a>        ; back, if not, to FAILED.
+; A usable sector has been found on the drive. HL addresses byte within map.
+        EX      (SP),HL         ; map address to stack, bring back data pointer.
+        PUSH    BC              ; preserve B the map byte mask.
+        IN      A,($EF)         ; test the drive.
+        AND     $01             ; examine 'write protect' bit.
+        JR      NZ,<A href="#L1374">L1374</a>        ; forward, if not protected, to NO-PRT.
+        RST     20H             ; Shadow Error Restart.
+        DEFB    $0E             ; Drive 'write' protected
+<a name="L1374"></a>;; <b>NO-PRT</b>
+L1374:  LD      A,$E6           ;      xx100110
+        OUT     ($EF),A         ; enable writing.
+        LD      BC,$0168        ; a delay value of 360 decimal.
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC pauses briefly as the
+                                ; record now approaches the tape heads.
+        CALL    <A href="#L15B3">L15B3</a>           ; routine OUT-M-BUF writes descriptor and
+                                ; data buffer.
+        LD      A,$EE           ;       xx101110
+        OUT     ($EF),A         ; disable writing.
+        POP     BC              ; restore the map bit.
+        POP     HL              ; and the address of the byte within microdrive
+                                ; map.
+        LD      A,B             ; transfer masked bit to A.
+        OR      (HL)            ; combine with status of other 7 sectors.
+        LD      (HL),A          ; update the map to show this sector is now
+                                ; used.
+        RET                     ; return.
+; ------------------------
+; THE <b><font color=#333388>'CLOSE FILE'</font></b> ROUTINE
+; ------------------------
+; <font color=#9900FF>Note.</font> The first entry point is not used.
+<a name="L138B"></a>;; <b>close-m</b>
+L138B:  PUSH    HL              ;
+        POP     IX              ;
+; <font color=#339933>(Hook Code: $23)</font>
+<a name="L138E"></a>;; <b>CLOSE-M2</b>
+L138E:  BIT     0,(IX+$18)      ; CHFLAG
+        JR      Z,<A href="#L139B">L139B</a>         ; forward to NOEMP
+        SET     1,(IX+$43)      ; RECFLG
+        CALL    <A href="#L12DA">L12DA</a>           ; routine WR-RECD
+<a name="L139B"></a>;; <b>NOEMP</b>
+L139B:  XOR     A               ;
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE
+        CALL    <A href="#L119F">L119F</a>           ; routine DEL-M-BUF
+        RET                     ; return after subroutine.
+; ------------------------------------------
+; THE <b><font color=#333388>'MAIN ERROR RESTART EMULATION'</font></b> ROUTINE
+; ------------------------------------------
+<a name="L13A3"></a>;; <b>ERR-RS</b>
+L13A3:  POP     HL              ;
+        LD      A,(HL)          ;
+        LD      ($5C3A),A       ; sv ERR_NR
+        RST     28H             ; Error Main ROM
+; ------------------------------------------
+; THE <b><font color=#333388>'FETCH HEADER FROM MICRODRIVE'</font></b> ROUTINE
+; ------------------------------------------
+;   This routine fetches the next valid 14-byte header to pass the tape heads
+;   ensuring that it is a header as opposed to a record descriptor.
+<a name="L13A9"></a>;; <b>GET-M-HD2</b>
+L13A9:  PUSH    IX              ; transfer start of channel
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0028        ; offset to HDFLAG
+        ADD     HL,DE           ; add to form first receiving location.
+        CALL    <A href="#L15E2">L15E2</a>           ; routine GET-M-HD reads 15 bytes from
+                                ; microdrive - last is a checksum byte.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R checksums the bytes.
+        JR      NZ,<A href="#L13A9">L13A9</a>        ; back, with error, to GET-M-HD2
+        BIT     0,(IX+$28)      ; test HDFLAG should be set.
+        JR      Z,<A href="#L13A9">L13A9</a>         ; back, if not a header, to GET-M-HD2
+        RET                     ; return - with HL addressing start of header.
+; ---------------------------------
+; THE <b><font color=#333388>'CHECK MAP BIT STATE'</font></b> ROUTINE
+; ---------------------------------
+;
+<a name="L13BF"></a>;; <b>CHK-MAP-2</b>
+L13BF:  LD      E,(IX+$44)      ; pick up record from RECNUM
+        JR      <A href="#L13C7">L13C7</a>           ; forward to ENTRY
+; ---
+<a name="L13C4"></a>;; <b>CHECK-MAP</b>
+L13C4:  LD      E,(IX+$29)      ; pick up sector from HDNUMB
+; -&gt;
+<a name="L13C7"></a>;; <b>ENTRY</b>
+L13C7:  LD      L,(IX+$1A)      ; fetch address of associated
+        LD      H,(IX+$1B)      ; microdrive map from CHMAP
+; the pseudo-map routine enters here with a temporary map address.
+<a name="L13CD"></a>;; <b>ENTRY-2</b>
+L13CD:  XOR     A               ; clear accumulator is one way to
+        LD      D,A             ; clear D in preparation for addition.
+        LD      A,E             ; transfer sector to A.
+        AND     $07             ; and mask off lower 8 bits for later
+        SRL     E               ; returning to E,
+        SRL     E               ; divide the
+        SRL     E               ; sector or record by eight.
+        ADD     HL,DE           ; add to map base to give address of map bit.
+        LD      B,A             ; now load sector mod 8 to B and
+        INC     B               ; increment to form counter 1 - 8.
+        XOR     A               ; clear A
+        SCF                     ; and set carry bit ready to rotate in.
+<a name="L13DD"></a>;; <b>ROTATE</b>
+L13DD:  RLA                     ; rotate left A
+        DJNZ    <A href="#L13DD">L13DD</a>           ; back, while counter not zero, to ROTATE
+        LD      B,A             ; return sector bit in B.
+        AND     (HL)            ; AND accumulator with map sector byte.
+        RET                     ; return - Z = free, NZ = occupied.
+; -----------------------------------
+; THE <b><font color=#333388>'RESET BIT IN MAP AREA'</font></b> ROUTINE
+; -----------------------------------
+;   This routine is called when opening a channel and by FORMAT, CAT and ERASE
+;   to mark a map bit representing a sector as available.
+<a name="L13E3"></a>;; <b>RES-B-MAP</b>
+L13E3:  CALL    <A href="#L13C4">L13C4</a>           ; routine CHECK-MAP fetches bit mask for map
+                                ; location addressed by HL into B register.
+        LD      A,B             ; fetch sector mask with one bit set.
+        CPL                     ; complement - seven bits set and one bit reset.
+        AND     (HL)            ; combine with other sector bits.
+        LD      (HL),A          ; and update map byte resetting the bit.
+        RET                     ; return.
+; ------------------------------------------
+; THE <b><font color=#333388>'CHECK '</font></b>PSEUDO-MAP' BIT STATE' ROUTINE
+; ------------------------------------------
+;
+<a name="L13EB"></a>;; <b>TEST-PMAP</b>
+L13EB:  PUSH    IX              ;
+        POP     HL              ;
+        LD      DE,$0052        ;
+        ADD     HL,DE           ;
+        LD      E,(IX+$29)      ; HDNUMB
+        JR      <A href="#L13CD">L13CD</a>           ; back to ENTRY-2
+; -------------------------------------
+; THE <b><font color=#333388>'DECREASE SECTOR COUNTER'</font></b> ROUTINE
+; -------------------------------------
+;
+<a name="L13F7"></a>;; <b>DEC-SECT</b>
+L13F7:  LD      BC,($5CC9)      ; sv SECTOR
+        DEC     BC              ;
+        LD      ($5CC9),BC      ; sv SECTOR
+        LD      A,B             ;
+        OR      C               ;
+        RET                     ;
+; ------------------------
+; THE <b><font color=#333388>'CHECK-NAME'</font></b> ROUTINE
+; ------------------------
+;
+<a name="L1403"></a>;; <b>CHK-NAME</b>
+L1403:  PUSH    IX              ; preserve original channel base address.
+        LD      B,$0A           ;
+<a name="L1407"></a>;; <b>ALL-CHARS</b>
+L1407:  LD      A,(HL)          ;
+        CP      (IX+$0E)        ; CHNAME
+        JR      NZ,<A href="#L1423">L1423</a>        ; forward to CKNAM-END
+        INC     HL              ;
+        INC     IX              ;
+        DEC     B               ;
+        DEC     C               ;
+        JR      NZ,<A href="#L1407">L1407</a>        ; back to ALL-CHARS
+        LD      A,B             ;
+        OR      A               ;
+        JR      Z,<A href="#L1423">L1423</a>         ; forward to CKNAM-END
+<a name="L1418"></a>;; <b>ALLCHR-2</b>
+L1418:  LD      A,(IX+$0E)      ; CHNAME
+        CP      $20             ;
+        JR      NZ,<A href="#L1423">L1423</a>        ; forward to CKNAM-END
+        INC     IX              ;
+        DJNZ    <A href="#L1418">L1418</a>           ; back to ALLCHR-2
+<a name="L1423"></a>;; <b>CKNAM-END</b>
+L1423:  POP     IX              ;
+        RET                     ;
+; -----------------------------------------
+; THE <b><font color=#333388>'CALCULATE/COMPARE CHECKSUMS'</font></b> ROUTINE
+; -----------------------------------------
+; Used for microdrive channels only.
+; While the two checksums within a Network buffer are simple 8-bit sums of
+; the data, the algorithm used for the microdrive channels is a little more
+; sophisticated as it avoids the formation of the result $FF. While across the
+; network a byte is as good as its neighbour, with microdrives the value $FF
+; might arise as a result of a failed read.
+; The same routine is used both to prepare the checksum prior to saving and to
+; calculate and compare the checksum after reading.
+; The first entry point is used for the 14 bytes of HDCHK and DESCHK
+; and the second entry point is used for the 512 bytes of DCHK.
+<a name="L1426"></a>;; <b>CHKS-HD-R</b>
+L1426:  LD      BC,$000E        ; fourteen bytes
+        JR      <A href="#L142E">L142E</a>           ; forward to CHKS-ALL
+; ---
+; -&gt;
+<a name="L142B"></a>;; <b>CHKS-BUFF</b>
+L142B:  LD      BC,$0200        ; 512 bytes.
+; common code.
+<a name="L142E"></a>;; <b>CHKS-ALL</b>
+L142E:  PUSH    HL              ; save pointer to first address.
+        LD      E,$00           ; initialize checksum to zero
+<a name="L1431"></a>;; <b>NXT-BYTE</b>
+L1431:  LD      A,E             ; fetch running sum
+        ADD     A,(HL)          ; add to current location.
+        INC     HL              ; point to next location.
+        ADC     A,$01           ; avoid the value $FF.
+        JR      Z,<A href="#L1439">L1439</a>         ; forward to STCHK
+        DEC     A               ; decrement.
+<a name="L1439"></a>;; <b>STCHK</b>
+L1439:  LD      E,A             ; update the 8-bit sum.
+        DEC     BC              ; reduce counter
+        LD      A,B             ; and check
+        OR      C               ; for zero.
+        JR      NZ,<A href="#L1431">L1431</a>        ; back, if not, to NXT-BYTE
+        LD      A,E             ; fetch running sum
+        CP      (HL)            ; compare to checksum contents
+        LD      (HL),A          ; before inserting the byte.
+        POP     HL              ; restore pointer to first address.
+        RET                     ; return - with zero flag set if sums agree.
+; ---------------------------------
+; THE <b><font color=#333388>'RESTORE STREAM DATA'</font></b> ROUTINE
+; ---------------------------------
+; When a channel is deleted, then the streams that point to channels beyond
+; that one have to have their offsets reduced by the deleted amount.
+; Also a stream that exactly matches the offset to the deleted channel, and
+; there could be several, will have its entry set to zero.
+; On entry, HL = offset, BC = $0253
+<a name="L1444"></a>;; <b>REST-STRM</b>
+L1444:  PUSH    HL              ; save the offset
+        LD      A,$10           ; maximum streams + 1
+        LD      HL,$5C16        ; the start of the user streams area STRMS_00
+<a name="L144A"></a>;; <b>NXT-STRM</b>
+L144A:  LD      ($5C5F),HL      ; save stream pointer temporarily in X_PTR
+        LD      E,(HL)          ; fetch low byte of offset.
+        INC     HL              ; bump address.
+        LD      D,(HL)          ; fetch high byte of streams offset.
+        POP     HL              ; retrieve the
+        PUSH    HL              ; supplied offset.
+        OR      A               ; clear carry.
+        SBC     HL,DE           ; subtract looking for an exact match
+        JR      NZ,<A href="#L145C">L145C</a>        ; forward, if not, to NOTRIGHT
+        LD      DE,$0000        ; else set displacement to zero.
+        JR      <A href="#L1463">L1463</a>           ; forward to STO-DISP to close the stream.
+; ---
+<a name="L145C"></a>;; <b>NOTRIGHT</b>
+L145C:  JR      NC,<A href="#L1469">L1469</a>        ; forward, if entry lower, to UPD-POINT -&gt;
+; else this stream entry is to be reduced by $0253 bytes.
+        EX      DE,HL           ; streams offset to HL
+        OR      A               ; clear carry
+        SBC     HL,BC           ; reduce by 595 decimal bytes
+        EX      DE,HL           ; transfer reduced entry to DE.
+<a name="L1463"></a>;; <b>STO-DISP</b>
+L1463:  LD      HL,($5C5F)      ; fetch stream address from X_PTR
+        LD      (HL),E          ; and insert
+        INC     HL              ; the updated
+        LD      (HL),D          ; offset.
+; -&gt;
+<a name="L1469"></a>;; <b>UPD-POINT</b>
+L1469:  LD      HL,($5C5F)      ; fetch stream address from X_PTR.
+        INC     HL              ; bump - each stream entry
+        INC     HL              ; is two bytes.
+        DEC     A               ; decrement the loop counter.
+        JR      NZ,<A href="#L144A">L144A</a>        ; back, if not zero, to NXT-STRM
+; else clean up and return.
+        LD      ($5C5F),A       ; set X_PTR_hi to zero resting value.
+        POP     HL              ; balance stack.
+        RET                     ; return.
+; -----------------------------------
+; THE <b><font color=#333388>'RESTORE MAP ADDRESSES'</font></b> ROUTINE
+; -----------------------------------
+; When a microdrive map is reclaimed, then all the addresses of the microdrive
+; maps in the "M" channels are examined and if higher than the deleted map, the
+; address is reduced by thirty two bytes.
+; On entry, HL = map address, BC = $0020.
+<a name="L1476"></a>;; <b>REST-MAP</b>
+L1476:  LD      BC,$0020        ; set BC to thirty two. Already done.
+        LD      IX,($5C4F)      ; load IX from system variable CHANS.
+        LD      DE,$0014        ; there are 20 bytes of the standard 4 channels
+        ADD     IX,DE           ; add to skip these.
+; now enter a loop.
+<a name="L1482"></a>;; <b>LCHAN</b>
+L1482:  LD      A,(IX+$00)      ; fetch first byte.
+        CP      $80             ; is it the channels area end-marker ?
+        RET     Z               ; return if so - all maps adjusted.       &gt;&gt;
+        PUSH    HL              ; save map address.
+        LD      A,(IX+$04)      ; fetch channel letter.
+        AND     $7F             ; reset bit 7.
+        CP      $4D             ; compare to "M"
+        JR      NZ,<A href="#L14A6">L14A6</a>        ; forward, if not, to LPEND
+; a microdrive channel has been found so compare the address of the map.
+        LD      E,(IX+$1A)      ; fetch address of the microdrive
+        LD      D,(IX+$1B)      ; map for this channel from CHMAP.
+        SBC     HL,DE           ; subtract from that of deleted map.
+        JR      NC,<A href="#L14A6">L14A6</a>        ; forward, if is lower, to LPEND
+; address of this microdrive map is higher than the one deleted.
+        EX      DE,HL           ; transfer address to HL.
+        OR      A               ; clear carry.
+        SBC     HL,BC           ; subtract thirty two.
+        LD      (IX+$1A),L      ; and place back
+        LD      (IX+$1B),H      ; in CHMAP.
+<a name="L14A6"></a>;; <b>LPEND</b>
+L14A6:  POP     HL              ; restore address of deleted map.
+        LD      E,(IX+$09)      ; fetch length of channel
+        LD      D,(IX+$0A)      ; to DE.
+        ADD     IX,DE           ; add to address next channel.
+        JR      <A href="#L1482">L1482</a>           ; loop back to LCHAN.
+; ------------------------------
+; THE <b><font color=#333388>'"M" CHANNEL DEFAULT'</font></b> DATA
+; ------------------------------
+;
+<a name="L14B1"></a>;; <b>MCH-DAT</b>
+L14B1:  DEFW    $0008           ; main ERROR-1
+        DEFW    $0008           ; main ERROR-1
+        DEFB    $CD             ; inverted "M" character
+        DEFW    <A href="#L12B3">L12B3</a>           ; MCHAN-OUT
+        DEFW    <A href="#L11FD">L11FD</a>           ; M-INPUT
+        DEFW    $0253           ; length
+        DEFW    $0000           ;
+        DEFB    $00             ;
+        DEFM    "          "    ; 10 spaces
+        DEFB    $FF             ; CHFLAG
+; -------------------
+; THE <b><font color=#333388>'PREAMBLE DATA'</font></b>
+; -------------------
+;   The PREAMBLE consists of twelve distinctive bytes that are saved to a
+;   microdrive cartridge before the data.  They are not read back but allow
+;   the ULA of the microdrive to recognize the start of a saved data block.
+<a name="L14CA"></a>;; <b>PREAMBLE</b>
+L14CA:  DEFB    $00, $00, $00
+        DEFB    $00, $00, $00
+        DEFB    $00, $00, $00
+        DEFB    $00, $FF, $FF
+; -------------------------------
+; THE <b><font color=#333388>'NOT-USED TOOLKIT'</font></b> ROUTINES
+; -------------------------------
+; The following four routines are for debugging
+; purposes during development.
+; ----------------------
+; THE <b><font color=#333388>'DISP-HEX'</font></b> ROUTINE
+; ----------------------
+;   display a byte as two hex characters.
+<a name="L14D6"></a>;; <b>DISP-HEX</b>
+L14D6:  PUSH    AF              ;
+        RRA                     ;
+        RRA                     ;
+        RRA                     ;
+        RRA                     ;
+        CALL    <A href="#L14DF">L14DF</a>           ; routine DISP-NIB
+        POP     AF              ;
+<a name="L14DF"></a>;; <b>DISP-NIB</b>
+L14DF:  AND     $0F             ;
+        CP      $0A             ;
+        JR      C,<A href="#L14E7">L14E7</a>         ; forward to CONV-1
+        ADD     A,$07           ;
+<a name="L14E7"></a>;; <b>CONV-1</b>
+L14E7:  ADD     A,$30           ;
+        CALL    <A href="#L14F8">L14F8</a>           ; routine DISP-CH
+        RET                     ;
+; -----------------------
+; THE <b><font color=#333388>'DISP-HEX2'</font></b> ROUTINE
+; -----------------------
+;   display a byte in hexadecimal followed by a space
+<a name="L14ED"></a>;; <b>DISP-HEX2</b>
+L14ED:  PUSH    AF              ;
+        CALL    <A href="#L14D6">L14D6</a>           ; routine DISP-HEX
+        LD      A,$20           ;
+        CALL    <A href="#L14F8">L14F8</a>           ; routine DISP-CH
+        POP     AF              ;
+        RET                     ;
+; ---------------------
+; THE <b><font color=#333388>'DISP-CH'</font></b> ROUTINE
+; ---------------------
+;
+<a name="L14F8"></a>;; <b>DISP-CH</b>
+L14F8:  PUSH    HL              ;
+        PUSH    DE              ;
+        PUSH    BC              ;
+        PUSH    AF              ;
+        EXX                     ;
+        PUSH    HL              ;
+        PUSH    DE              ;
+        PUSH    BC              ;
+        PUSH    AF              ;
+        LD      HL,($5C51)      ; sv CURCHL
+        PUSH    HL              ;
+        PUSH    AF              ;
+        LD      A,$02           ;
+        RST     10H             ; CALBAS
+        DEFW    $1601           ; main CHAN-OPEN
+        POP     AF              ;
+        RST     10H             ; CALBAS
+        DEFW    $0010           ; main PRINT-A
+        POP     HL              ;
+        LD      ($5C51),HL      ; sv CURCHL
+        POP     AF              ;
+        POP     BC              ;
+        POP     DE              ;
+        POP     HL              ;
+        EXX                     ;
+        POP     AF              ;
+        POP     BC              ;
+        POP     DE              ;
+        POP     HL              ;
+        RET                     ;
+; ----------------------
+; THE <b><font color=#333388>'HEX-LINE'</font></b> ROUTINE
+; ----------------------
+;   The Master routine which displays ten bytes of memory, addressed by HL,
+;   in Hexadecimal followed by a CR.  The thirty output characters sit
+;   comfortably within the 32 character display of the Spectrum.
+<a name="L151D"></a>;; <b>HEX-LINE</b>
+L151D:  PUSH    HL              ;
+        PUSH    BC              ;
+        PUSH    AF              ;
+        LD      B,$0A           ;
+<a name="L1522"></a>;; <b>HEX-LINE2</b>
+L1522:  LD      A,(HL)          ;
+        CALL    <A href="#L14ED">L14ED</a>           ; routine DISP-HEX2
+        INC     HL              ;
+        DJNZ    <A href="#L1522">L1522</a>           ; back to HEX-LINE2
+        LD      A,$0D           ;
+        CALL    <A href="#L14F8">L14F8</a>           ; routine DISP-CH
+        POP     AF              ;
+        POP     BC              ;
+        POP     HL              ;
+        RET                     ; return.
+; --------------------------------
+; THE <b><font color=#333388>'SELECT DRIVE MOTOR'</font></b> ROUTINE
+; --------------------------------
+; <font color=#339933>(Hook Code: $21)</font>
+;   This important routine is called on over twenty occasions to activate a
+;   microdrive whose number is in the accumulator, or with a parameter of
+;   zero, to stop all motors.  It is the sole means of controlling the real
+;   or virtual bank of eight microdrives.
+;   It is called with interrupts disabled and this condition should be in
+;   force when the Hook Code is used.
+<a name="L1532"></a>;; <b>SEL-DRIVE</b>
+L1532:  PUSH    HL              ; preserve the original HL value throughout.
+        CP      $00             ; is the parameter zero ?
+        JR      NZ,<A href="#L153D">L153D</a>        ; forward, if not, to TURN-ON.
+;   The requirement is to ensure that all eight drives are switched off.
+        CALL    <A href="#L1565">L1565</a>           ; routine SW-MOTOR with A holding zero.
+        EI                      ; Enable Interrupts.
+        POP     HL              ; restore original HL value.
+        RET                     ; return.                               &gt;&gt;
+; --------------------
+; THE <b><font color=#333388>'TURN ON'</font></b> BRANCH
+; --------------------
+;   This route turns on a drive in the range 1 - 8.  If the Hook Code has
+;   been erroneously invoked with a higher value, then this will be treated
+;   in much the same way as with zero.  See later.
+<a name="L153D"></a>;; <b>TURN-ON</b>
+L153D:  DI                      ; Disable Interrupts.
+        CALL    <A href="#L1565">L1565</a>           ; routine SW-MOTOR
+        LD      HL,$1388        ; prepare decimal 5,000 delay value.
+<a name="L1544"></a>;; <b>TON-DELAY</b>
+L1544:  DEC     HL              ; a simple
+        LD      A,H             ; delay loop to
+        OR      L               ; let things settle down.
+        JR      NZ,<A href="#L1544">L1544</a>        ; back, if not zero, to TON-DELAY
+        LD      HL,$1388        ; load with five thousand again.
+; Now enter another 5000 loop testing for break and searching for a GAP on
+; the tape at each iteration.
+<a name="L154C"></a>;; <b>REPTEST</b>
+L154C:  LD      B,$06           ; six consecutive reads required to register
+                                ; as a gap.
+<a name="L154E"></a>;; <b>CHK-PRES</b>
+L154E:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK allows the user to stop.
+        IN      A,($EF)         ; read the microdrive port.
+        AND     $04             ; test for the gap bit
+        JR      NZ,<A href="#L155B">L155B</a>        ; forward, if not, to NOPRES
+        DJNZ    <A href="#L154E">L154E</a>           ; loop back six times to CHK-PRES
+; A gap has been found - a formatted cartridge is in the drive.
+        POP     HL              ; restore original HL value.
+        RET                     ; return with motor running, interrupts
+                                ; disabled.                               &gt;&gt;
+; -------------------
+; THE <b><font color=#333388>'NO GAP'</font></b> BRANCH
+; -------------------
+;   If no gap signal found on drive so far then continue counting down from
+;   5000 and looping back to test for six gaps.
+<a name="L155B"></a>;; <b>NOPRES</b>
+L155B:  DEC     HL              ; decrement the counter
+        LD      A,H             ; test for
+        OR      L               ; zero.
+        JR      NZ,<A href="#L154C">L154C</a>        ; back, if not, to REPTEST
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE with accumulator zero
+                                ; stops the drive motor.
+        RST     20H             ; Shadow Error Restart
+        DEFB    $10             ; 'Microdrive not present'
+; -----------------------------
+; THE <b><font color=#333388>'SWITCH MOTOR'</font></b> SUBROUTINE
+; -----------------------------
+;   The main developer of the microdrives and acknowledged co-inventor was
+;   the late Ben Cheese, 14-Jul-1954 - 15-Jan-2001.
+;
+;   This ROM software always handles the switching of microdrives as if
+;   there were eight drives connected.  There is no short cut to directly
+;   switch on a drive and they must be handled as an array of eight devices.
+;   Each microdrive includes a D-flip flop, capable of holding logic state
+;   one or zero.  When the flip-flop is set at logic one then the
+;   recording/playback device is switched on.
+;
+;   The first microdrive has the D-input terminal of the flip-flop connected
+;   to the comms data line of the Interface 1 and the clock-input terminal
+;   connected to the clock-output terminal of Interface 1.  Subsequent
+;   microdrives have the D-input terminal connected to the Q-output terminal
+;   of the next innermost drive/flip-flop and the CLOCK-input terminal
+;   connected to the CLOCK-input terminal of the same adjacent
+;   drive/flip-flop.
+;
+;   The eight microdrives thus behave as a shift register allowing a logic 1
+;   condition, originating at the Interface 1 control device, to be loaded
+;   into the first flip-flop by a single clock pulse and to be shifted out
+;   to the appropriate flip-flop by a series of further clock pulses.
+;
+;   As eight pulses will be required, then the logic state of drive eight is
+;   considered first and drive one is the last to be considered.
+;
+;   By negating the drive number and adding nine, the routine below begins
+;   by effecting this reversal and, by converting zero to nine, it ensures
+;   that eight logic zeros are shifted out for this case and for the case
+;   of any out-of-range parameter, which can arise in the case of a User
+;   experimenting with Hook Codes.
+;   The limit of eight microdrives is set in the routine below and not in
+;   hardware.
+;
+;   As Ben pointed out on his patent from which some of these details are
+;   taken, "it will be appreciated that the control device may be used to
+;   select associated devices other than recording/playback devices and that
+;   any number of associated devices may be accommodated by use of the
+;   technique described."
+<a name="L1565"></a>;; <b>SW-MOTOR</b>
+L1565:  PUSH    DE              ; preserve the original DE value throughout.
+        LD      DE,$0100        ; load DE with the constants logic one and
+                                ; logic zero.
+        NEG                     ; negate the supplied drive number 0 - n
+        ADD     A,$09           ; add 9 so that 0 = 9, -1 = 8, -8 = 1, -10 = -1
+        LD      C,A             ; place the reversed parameter in C.
+        LD      B,$08           ; set clock shift counter to eight.
+<a name="L1570"></a>;; <b>ALL-MOTRS</b>
+L1570:  DEC     C               ; decrement the drive selector.
+        JR      NZ,<A href="#L1586">L1586</a>        ; forward, if not in position, to OFF-MOTOR.
+; The time has come to send out a signal to start this drive.
+        LD      A,D             ; select logic one.
+        OUT     ($F7),A         ; output to data port.
+        LD      A,$EE           ; select comms clock 1, comms data 0
+        OUT     ($EF),A         ; output to D-flip flop.
+        CALL    <A href="#L15A2">L15A2</a>           ; routine DEL-S-1 holds for a millisecond.
+        LD      A,$EC           ; select comms clock 0, comms data 0
+        OUT     ($EF),A         ; output to D-flip flops.
+        CALL    <A href="#L15A2">L15A2</a>           ; routine DEL-S-1 holds for a millisecond.
+        JR      <A href="#L1597">L1597</a>           ; forward to NXT-MOTOR
+; ---
+<a name="L1586"></a>;; <b>OFF-MOTOR</b>
+L1586:  LD      A,$EF           ; select comms clock 1, comms data 1
+        OUT     ($EF),A         ; output to D-flip flop.
+        LD      A,E             ; select logic 0.
+        OUT     ($F7),A         ; output to data port.
+        CALL    <A href="#L15A2">L15A2</a>           ; routine DEL-S-1 holds for a millisecond.
+        LD      A,$ED           ; select comms clock 0, comms data 1
+        OUT     ($EF),A         ; output to microdrive port.
+        CALL    <A href="#L15A2">L15A2</a>           ; routine DEL-S-1 holds for a millisecond.
+<a name="L1597"></a>;; <b>NXT-MOTOR</b>
+L1597:  DJNZ    <A href="#L1570">L1570</a>           ; back, for all eight drives, to ALL-MOTRS.
+        LD      A,D             ; select logic one.
+        OUT     ($F7),A         ; output to data port.
+        LD      A,$EE           ; select comms clock 1, comms data 0.
+        OUT     ($EF),A         ; output to microdrive port.
+        POP     DE              ; restore original DE value.
+        RET                     ; return.
+; ---------------------------------
+; THE <b><font color=#333388>'1 MILLISECOND DELAY'</font></b> ROUTINE
+; ---------------------------------
+;   This subroutine is used to time the transitions of the Delay-flip-flops
+;   used, above, to control the array of microdrives attached to Interface 1.
+;   Delay flip flops become unstable if transitions are too close together
+;   and this routine provides a 1 millisecond delay between clock pulses.
+<a name="L15A2"></a>;; <b>DEL-S-1</b>
+L15A2:  PUSH    BC              ; preserve counters.
+        PUSH    AF              ;
+        LD      BC,$0087        ; 135 decimal.
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC
+        POP     AF              ;
+        POP     BC              ; restore counters
+        RET                     ; return.
+; ---------------------------------------------
+; THE <b><font color=#333388>'SEND HEADER BLOCK TO MICRODRIVE'</font></b> ROUTINE
+; ---------------------------------------------
+;   Routine is called once from the FORMAT routine.
+<a name="L15AD"></a>;; <b>OUT-M-HD</b>
+L15AD:  PUSH    HL              ;
+        LD      DE,$001E        ; 30 bytes.
+        JR      <A href="#L15B7">L15B7</a>           ; forward to OUT-M-BLK -&gt;
+; -------------------------------------------
+; THE <b><font color=#333388>'SEND DATA BLOCK TO MICRODRIVE'</font></b> ROUTINE
+; -------------------------------------------
+;
+<a name="L15B3"></a>;; <b>OUT-M-BUF</b>
+L15B3:  PUSH    HL              ;
+        LD      DE,$021F        ; 543 bytes.
+; -&gt; Common code.
+<a name="L15B7"></a>;; <b>OUT-M-BLK</b>
+L15B7:  IN      A,($EF)         ;
+        AND     $01             ; isolate write prot. bit.
+        JR      NZ,<A href="#L15BF">L15BF</a>        ; forward to NOT-PROT
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0E             ; Drive 'write' protected
+; ---
+<a name="L15BF"></a>;; <b>NOT-PROT</b>
+L15BF:  LD      A,($5CC6)       ; sv IOBORD
+        OUT     ($FE),A         ;
+        LD      A,$E2           ;
+        OUT     ($EF),A         ;
+        INC     D               ;
+        LD      A,D             ;
+        LD      B,E             ;
+        LD      C,$E7           ;
+        NOP                     ;
+        NOP                     ;
+        NOP                     ;
+<a name="L15D0"></a>;; <b>OUT-M-BYT</b>
+L15D0:  OTIR                    ;
+        DEC     A               ;
+        JR      NZ,<A href="#L15D0">L15D0</a>        ; back to OUT-M-BYT
+        LD      A,$E6           ;
+        OUT     ($EF),A         ;
+        CALL    <A href="#L0D4D">L0D4D</a>           ; routine BORD-REST
+        POP     HL              ;
+        RET                     ; return.
+; -----------------------------
+; THE <b><font color=#333388>'SIGNAL ERROR'</font></b> EXIT POINT
+; -----------------------------
+;   This exit point is used  twice from the next routines when the required
+;   header or record block is not found within the requisite time.
+<a name="L15DE"></a>;; <b>SIGN-ERR</b>
+L15DE:  POP     BC              ; balance the stack.
+        POP     HL              ; first byte of destination.
+        INC     (HL)            ; increment RECFLG or HDFLAG.
+        RET                     ; return.
+; --------------------------------------------------
+; THE <b><font color=#333388>'RECEIVE BLOCK FROM MICRODRIVE HEADER'</font></b> ROUTINE
+; --------------------------------------------------
+;
+<a name="L15E2"></a>;; <b>GET-M-HD</b>
+L15E2:  PUSH    HL              ; save destination
+        LD      DE,$000F        ; set fifteen bytes to load.
+        LD      HL,$0000        ; set large delay when waiting for a header.
+        JR      <A href="#L15F2">L15F2</a>           ; forward to GET-M-BLK
+; --------------------------------------------------
+; THE <b><font color=#333388>'RECEIVE BLOCK FROM MICRODRIVE RECORD'</font></b> ROUTINE
+; --------------------------------------------------
+;
+<a name="L15EB"></a>;; <b>GET-M-BUF</b>
+L15EB:  PUSH    HL              ; save destination.
+        LD      DE,$0210        ; set 528d bytes to load.
+        LD      HL,$01F4        ; set delay counter to 500d.
+; --&gt;
+<a name="L15F2"></a>;; <b>GET-M-BLK</b>
+L15F2:  LD      B,E             ; load B register for first INIR load.
+        LD      C,D             ; load C register with count of further loads.
+        INC     C               ; adjust to count down to zero.
+        PUSH    BC              ; save the INIR counters.
+;
+<a name="L15F6"></a>;; <b>CHK-AGAIN</b>
+L15F6:  LD      B,$08           ; set gap counter to eight.
+        DEC     HL              ;
+        LD      A,H             ;
+        OR      L               ;
+        JR      Z,<A href="#L15DE">L15DE</a>         ; back to SIGN-ERR
+<a name="L15FD"></a>;; <b>CHKLOOP</b>
+L15FD:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+        IN      A,($EF)         ;
+        AND     $04             ; isolate gap bit.
+        JR      Z,<A href="#L15F6">L15F6</a>         ; back to CHK-AGAIN
+        DJNZ    <A href="#L15FD">L15FD</a>           ; back to CHKLOOP
+<a name="L1608"></a>;; <b>CHK-AG-2</b>
+L1608:  LD      B,$06           ;
+        DEC     HL              ;
+        LD      A,H             ;
+        OR      L               ;
+        JR      Z,<A href="#L15DE">L15DE</a>         ; back to SIGN-ERR
+<a name="L160F"></a>;; <b>CHK-LP-2</b>
+L160F:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+        IN      A,($EF)         ;
+        AND     $04             ; isolate gap bit.
+        JR      NZ,<A href="#L1608">L1608</a>        ; back to CHK-AG-2
+        DJNZ    <A href="#L160F">L160F</a>           ; back to CHK-LP-2
+        LD      A,$EE           ;
+        OUT     ($EF),A         ;
+        LD      B,$3C           ; set count 60 decimal.
+<a name="L1620"></a>;; <b>DR-READY</b>
+L1620:  IN      A,($EF)         ;
+        AND     $02             ; isolate sync bit.
+        JR      Z,<A href="#L162A">L162A</a>         ; forward to READY-RE
+        DJNZ    <A href="#L1620">L1620</a>           ; back to DR-READY
+        JR      <A href="#L15F6">L15F6</a>           ; back to CHK-AGAIN
+; ---
+<a name="L162A"></a>;; <b>READY-RE</b>
+L162A:  POP     BC              ; retrieve counters from the stack.
+        POP     HL              ; retrieve the destination
+        PUSH    HL              ; and stack again.
+        CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK.
+        LD      A,C             ; transfer repeat counter to A.
+        LD      C,$E7           ; set port to $E7.
+;   Now the INIR (INput to memory Increment and Repeat) instruction is used.
+<a name="L1633"></a>;; <b>IN-M-BLK</b>
+L1633:  INIR                    ; read B bytes from port C to destination HL.
+;   B (zero) will now count 256 bytes if first block was not the total.
+        DEC     A               ; decrement repeat counter.
+        JR      NZ,<A href="#L1633">L1633</a>        ; back, if not zero, to IN-M-BLK
+;   All bytes, 15 or 528 have now been read.
+        LD      A,$EE           ;
+        OUT     ($EF),A         ;
+        POP     HL              ; restore pointer to first byte.
+        RET                     ; return.
+; ----------------------
+; THE <b><font color=#333388>'TEST-BRK'</font></b> ROUTINE
+; ----------------------
+;   <font color=#9900FF>Note.</font> used more consistently in this ROM.
+<a name="L163E"></a>;; <b>TEST-BRK</b>
+L163E:  LD      A,$7F           ; read port $7FFE - keys B, N, M, SYM, SPACE.
+        IN      A,($FE)         ;
+        RRA                     ; test for SPACE key.
+        RET     C               ; return if not pressed.
+        LD      A,$FE           ; read port $FEFE - keys SHIFT, Z, X, C, V.
+        IN      A,($FE)         ;
+        RRA                     ; test for SHIFT key.
+        RET     C               ; return if not pressed.
+        CALL    <A href="#L0D4D">L0D4D</a>           ; routine BORD-REST.
+        LD      (IY+$00),$14    ; set ERR_NR to main 'L BREAK into program'
+        RST     28H             ; invoke the Main ROM error routine.
+; ----------------------
+; THE <b><font color=#333388>'DELAY-BC'</font></b> ROUTINE
+; ----------------------
+;
+<a name="L1652"></a>;; <b>DELAY-BC</b>
+L1652:  PUSH    AF              ;
+<a name="L1653"></a>;; <b>DELAY-BC1</b>
+L1653:  DEC     BC              ;
+        LD      A,B             ;
+        OR      C               ;
+        JR      NZ,<A href="#L1653">L1653</a>        ; back to DELAY-BC1
+        POP     AF              ;
+        RET                     ;
+; ------------------------
+; THE <b><font color=#333388>'READ BLOCK'</font></b> ROUTINE
+; ------------------------
+;   <font color=#9900FF>Note.</font> new in this ROM.
+;   Used by format routine.
+<a name="L165A"></a>;; <b>READ-BLK</b>
+L165A:  PUSH    HL
+        PUSH    BC
+<a name="L165C"></a>;; <b>RDLOOP1</b>
+L165C:  LD      B,$08
+<a name="L165E"></a>;; <b>RDLOOP2</b>
+L165E:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+        IN      A,($EF)
+        AND     $04             ; isolate gap bit.
+        JR      Z,<A href="#L165C">L165C</a>         ; back to RDLOOP1
+        DJNZ    <A href="#L165E">L165E</a>           ; back to RDLOOP2
+<a name="L1669"></a>;; <b>RDLOOP3</b>
+L1669:  LD      B,$06
+<a name="L166B"></a>;; <b>RDLOOP4</b>
+L166B:  CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+        IN      A,($EF)
+        AND     $04             ; isolate gap bit.
+        JR      NZ,<A href="#L1669">L1669</a>        ; back to RDLOOP3
+        DJNZ    <A href="#L166B">L166B</a>           ; back to RDLOOP4
+        LD      A,$EE
+        OUT     ($EF),A
+        LD      B,$3C           ; set counter to 60d.
+<a name="L167C"></a>;; <b>SYNC-RD</b>
+L167C:  IN      A,($EF)
+        AND     $02             ; isolate sync bit.
+        JR      Z,<A href="#L1686">L1686</a>         ; forward to READY-R2
+        DJNZ    <A href="#L167C">L167C</a>           ; back to SYNC-RD
+        JR      <A href="#L165C">L165C</a>           ; back to RDLOOP1
+; ---
+<a name="L1686"></a>;; <b>READY-R2</b>
+L1686:  POP     BC
+        POP     HL
+        PUSH    HL
+        CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+        LD      C,$E7           ; port
+        LD      E,$FC           ; required test byte
+        LD      B,$0F           ; initial counter.
+        LD      D,$64           ; final counter.
+        INIR
+<a name="L1696"></a>;; <b>RD-BYT-1</b>
+L1696:  IN      A,(C)
+        CP      E
+        JR      NZ,<A href="#L16AD">L16AD</a>        ; forward to ENDRD
+        DJNZ    <A href="#L1696">L1696</a>           ; back to RD-BYT-1
+<a name="L169D"></a>;; <b>RD-BYT-2</b>
+L169D:  IN      A,(C)
+        CP      E
+        JR      NZ,<A href="#L16AD">L16AD</a>        ; forward to ENDRD
+        DJNZ    <A href="#L169D">L169D</a>           ; back to RD-BYT-2
+        LD      B,D             ; final counter is $64
+<a name="L16A5"></a>;; <b>RD-BYT-3</b>
+L16A5:  IN      A,(C)
+        CP      E
+        JR      NZ,<A href="#L16AD">L16AD</a>        ; forward to ENDRD
+        DJNZ    <A href="#L16A5">L16A5</a>           ; back to RD-BYT-3
+        XOR     A               ; set zero flag to signal successful read
+<a name="L16AD"></a>;; <b>ENDRD</b>
+L16AD:  POP     HL
+        RET                     ; return.
+; -------------------------
+; THE <b><font color=#333388>'WRITE BLOCK'</font></b> ROUTINE
+; -------------------------
+;   <font color=#9900FF>Note.</font> new in this ROM.
+;   Called once from the FORMAT routine.
+<a name="L16AF"></a>;; <b>WR-BLK</b>
+L16AF:  PUSH    HL              ; preserve HL throughout.
+        LD      A,($5CC6)       ; fetch the value of IOBORD
+        OUT     ($FE),A         ; and change the border colour.
+        LD      A,$E2
+        OUT     ($EF),A         ; enable writing
+        LD      E,$66
+        LD      C,$E7
+        LD      B,$1B
+        LD      A,$FC           ; test byte written
+        NOP                     ;
+        OTIR                    ;
+<a name="L16C4"></a>;; <b>WR-BYT-1</b>
+L16C4:  OUT     (C),A
+        DJNZ    <A href="#L16C4">L16C4</a>           ; back to WR-BYT-1
+<a name="L16C8"></a>;; <b>WR-BYT-2</b>
+L16C8:  OUT     (C),A
+        DJNZ    <A href="#L16C8">L16C8</a>           ; back to WR-BYT-2
+        LD      B,E             ; load counter with $66
+<a name="L16CD"></a>;; <b>WR-BYT-3</b>
+L16CD:  OUT     (C),A
+        DJNZ    <A href="#L16CD">L16CD</a>           ; back to WR-BYT-3
+        LD      A,$E6
+        OUT     ($EF),A
+        CALL    <A href="#L0D4D">L0D4D</a>           ; routine BORD-REST
+        POP     HL              ; restore initial HL value.
+        RET                     ; return.
+; --------------------
+; THE <b><font color=#333388>'UNUSED'</font></b> SECTION
+; --------------------
+;   Contains copyright holder and initials of the main programmer.  The rest
+;   is set to $FF.  This section is situated before the fixed-position CLOSE
+;   rectification routine.
+        DEFB    $7F             ; copyright  &copy;
+        DEFM    " 1983 Sinclair"
+        DEFM    " Research Ltd"
+        DEFM    " MJB "         ; Martin Brennan
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+        DEFB    $FF
+; --------------------------
+; THE <b><font color=#333388>'CLOSE STREAM'</font></b> ROUTINE
+; --------------------------
+;   <font color=#9900FF>Note.</font> An instruction fetch on main address L1708 pages in this ROM.
+<a name="L1708"></a>;; <b>CLOSE-CH</b>
+L1708:  INC     HL              ; Same instruction as in Main ROM
+        RST     30H             ; Create the new system variables
+;   <font color=#9900FF>Note.</font> If extra System Variables were created then the accumulator will
+;   now hold the value 1 from the setting of COPIES.
+;   A command like       OPEN #7,"s" : CLOSE #7      will not work.
+;   If the system variables were already created then it is possible to
+;   derive the stream from the accumulator by reversing the operations
+;   that were performed on the value in the main ROM.
+        SRL     A               ; Shift Right Logical halves the value
+        SUB     $03             ; Subtraction produced the original stream.
+        RES     1,(IY+$7C)      ; set FLAGS_3 to indicate a CLOSE operation.
+        CALL    <A href="#L1718">L1718</a>           ; routine CLOSE (below)
+        JP      <A href="#L05C1">L05C1</a>           ; jump back to normal command exit at END1
+; ---------------------------
+; THE <b><font color=#333388>'CLOSE COMMAND'</font></b> ROUTINE
+; ---------------------------
+;   This command is called from above and also from ALL-STRMS as part of the
+;   CLEAR # command execution.
+<a name="L1718"></a>;; <b>CLOSE</b>
+L1718:  RST     10H             ; CALBAS
+        DEFW    $1727           ; main STR-DATA1
+;   Now perform the check that should have taken place in the original ROM.
+        LD      A,C             ; Test offset for zero.
+        OR      B               ;
+        RET     Z               ; Return if the stream is already closed.
+        PUSH    BC              ;
+        PUSH    HL              ;
+        LD      HL,($5C4F)      ; sv CHANS
+        DEC     HL              ;
+        ADD     HL,BC           ;
+        EX      (SP),HL         ;
+        RST     10H             ; CALBAS
+        DEFW    $16EB           ; main CLOSEX
+        LD      HL,($5C4F)      ; sv CHANS
+        LD      DE,$0014        ;
+        ADD     HL,DE           ;
+        POP     DE              ;
+        SCF                     ;
+        SBC     HL,DE           ;
+        POP     BC              ;
+        RET     NC              ;
+        PUSH    BC              ;
+        PUSH    DE              ;
+        EX      DE,HL           ;
+        LD      ($5C51),HL      ; sv CURCHL
+        INC     HL              ;
+        INC     HL              ;
+        INC     HL              ;
+        INC     HL              ;
+        LD      A,(HL)          ; fetch the letter.
+;   Now mark the channel as temporary so that if anything goes wrong, such
+;   as the user pressing BREAK, then the channel can be reclaimed by CLEAR #.
+L1741:  SET     7,(HL)          ; As suggested by Andrew Pennell 1983.
+        LD      DE,$0005        ;
+        ADD     HL,DE           ;
+        LD      E,(HL)          ;
+        INC     HL              ;
+        LD      D,(HL)          ;
+        PUSH    DE              ;
+        CP      $54             ; compare to "T"
+        JR      NZ,<A href="#L175C">L175C</a>        ; forward to CL-N-CH
+        BIT     1,(IY+$7C)      ; sv FLAGS_3
+        JR      NZ,<A href="#L177D">L177D</a>        ; forward to RCLM-CH
+        LD      A,$0D
+        CALL    <A href="#L0D07">L0D07</a>           ; routine BCHAN-OUT
+        JR      <A href="#L177D">L177D</a>           ; forward to RCLM-CH
+; ---
+<a name="L175C"></a>;; <b>CL-N-CH</b>
+L175C:  CP      $4E             ; character "N" ?
+        JR      NZ,<A href="#L176B">L176B</a>        ; forward to CL-M-CH
+        BIT     1,(IY+$7C)      ; sv FLAGS_3
+        JR      NZ,<A href="#L177D">L177D</a>        ; forward to RCLM-CH
+        CALL    <A href="#L0FAE">L0FAE</a>           ; routine SEND-NEOF
+        JR      <A href="#L177D">L177D</a>           ; forward to RCLM-CH
+; ---
+<a name="L176B"></a>;; <b>CL-M-CH</b>
+L176B:  CP      $4D             ; character "M"
+        JR      NZ,<A href="#L177D">L177D</a>        ; forward to RCLM-CH
+        POP     DE              ;
+        POP     IX              ;
+        POP     DE              ;
+        BIT     1,(IY+$7C)      ; sv FLAGS_3
+        JP      Z,<A href="#L138E">L138E</a>         ; jump to CLOSE-M2
+        JP      <A href="#L119F">L119F</a>           ; jump to DEL-M-BUF
+; ---
+<a name="L177D"></a>;; <b>RCLM-CH</b>
+L177D:  POP     BC              ;
+        POP     HL              ;
+        PUSH    BC              ;
+        RST     10H             ; CALBAS
+        DEFW    $19E8           ; main RECLAIM-2
+        XOR     A               ;
+        LD      HL,$5C16        ; sv STRMS_00
+<a name="L1787"></a>;; <b>UPD-STRM</b>
+L1787:  LD      E,(HL)          ;
+        INC     HL              ;
+        LD      D,(HL)          ;
+        DEC     HL              ;
+        LD      ($5C5F),HL      ; sv X_PTR
+        POP     BC              ;
+        POP     HL              ;
+        PUSH    HL              ;
+        PUSH    BC              ;
+        AND     A               ;
+        SBC     HL,DE           ;
+        JR      NC,<A href="#L17A2">L17A2</a>        ; forward to UPD-NXT-S
+        EX      DE,HL           ;
+        AND     A               ;
+        SBC     HL,BC           ;
+        EX      DE,HL           ;
+        LD      HL,($5C5F)      ; sv X_PTR
+        LD      (HL),E          ;
+        INC     HL              ;
+        LD      (HL),D          ;
+<a name="L17A2"></a>;; <b>UPD-NXT-S</b>
+L17A2:  LD      HL,($5C5F)      ; sv X_PTR
+        INC     HL              ;
+        INC     HL              ;
+        INC     A               ;
+        CP      $10             ;
+        JR      C,<A href="#L1787">L1787</a>         ; back to UPD-STRM
+        LD      (IY+$26),$00    ; sv X_PTR_hi
+        POP     HL              ;
+        POP     HL              ;
+        RES     1,(IY+$7C)      ; sv FLAGS_3
+        RET                     ; return.
+; ----------------------------------------
+; THE <b><font color=#333388>'RECLAIM TEMPORARY CHANNELS'</font></b> ROUTINE
+; ----------------------------------------
+;
+<a name="L17B7"></a>;; <b>RCL-T-CH</b>
+L17B7:  LD      IX,($5C4F)      ; sv CHANS
+        LD      DE,$0014
+        ADD     IX,DE
+<a name="L17C0"></a>;; <b>EX-CHANS</b>
+L17C0:  LD      A,(IX+$00)      ; first character of channel
+        CP      $80             ; is it the end-marker ?
+        JR      NZ,<A href="#L17D0">L17D0</a>        ; forward to CHK-TEMPM
+        LD      A,$EE
+        OUT     ($EF),A
+        XOR     A
+        JP      <A href="#L1532">L1532</a>           ; jump to SEL-DRIVE
+; ---
+        RET                     ; unused - the above JP was probably once a CALL.
+; ---
+<a name="L17D0"></a>;; <b>CHK-TEMPM</b>
+L17D0:  LD      A,(IX+$04)      ; channel letter
+        CP      $CD             ; is it an inverted "M" ?
+        JR      NZ,<A href="#L17DC">L17DC</a>        ; forward to CHK-TEMPN
+        CALL    <A href="#L119F">L119F</a>           ; routine DEL-M-BUF
+        JR      <A href="#L17B7">L17B7</a>           ; back to RCL-T-CH
+<a name="L17DC"></a>;; <b>CHK-TEMPN</b>
+L17DC:  CP      $CE             ; is channel letter an inverted "N" ?
+        JR      NZ,<A href="#L17EB">L17EB</a>        ; forward to PT-N-CHAN
+        LD      BC,$0114
+        PUSH    IX
+        POP     HL
+        RST     10H             ; CALBAS
+        DEFW    $19E8           ; main RECLAIM-2
+        JR      <A href="#L17B7">L17B7</a>           ; back to RCL-T-CH
+<a name="L17EB"></a>;; <b>PT-N-CHAN</b>
+L17EB:  LD      E,(IX+$09)      ; length of
+        LD      D,(IX+$0A)      ; channel
+        ADD     IX,DE
+        JR      <A href="#L17C0">L17C0</a>           ; back to EX-CHANS
+; --------------------------
+; THE <b><font color=#333388>'MOVE COMMAND'</font></b> ROUTINE
+; --------------------------
+;
+<a name="L17F5"></a>;; <b>MOVE</b>
+L17F5:  SET     4,(IY+$7C)      ; update FLAGS_3 to indicate a MOVE is in
+                                ; progress - see INKEY$
+        CALL    <A href="#L1859">L1859</a>           ; routine OP-STRM
+        LD      HL,($5C4F)      ; sv CHANS
+        PUSH    HL
+        CALL    <A href="#L059F">L059F</a>           ; routine EX-D-STR
+        CALL    <A href="#L1859">L1859</a>           ; routine OP-STRM
+        CALL    <A href="#L059F">L059F</a>           ; routine EX-D-STR
+        POP     DE
+        LD      HL,($5C4F)      ; sv CHANS
+        OR      A
+        SBC     HL,DE
+        LD      DE,($5CDA)      ; sv N_STR1
+        ADD     HL,DE
+        LD      ($5CDA),HL      ; sv N_STR1
+<a name="L1818"></a>;; <b>M-AGAIN</b>
+L1818:  LD      HL,($5CDA)      ; sv N_STR1
+        LD      ($5C51),HL      ; sv CURCHL
+<a name="L181E"></a>;; <b>I-AGAIN</b>
+L181E:  RST     10H             ; CALBAS
+        DEFW    $15E6           ; main INPUT-AD
+        JR      C,<A href="#L1827">L1827</a>         ; forward to MOVE-OUT
+        JR      Z,<A href="#L181E">L181E</a>         ; back to I-AGAIN
+        JR      <A href="#L1832">L1832</a>           ; forward to MOVE-EOF
+<a name="L1827"></a>;; <b>MOVE-OUT</b>
+L1827:  LD      HL,($5CE2)      ; sv D_STR2
+        LD      ($5C51),HL      ; sv CURCHL
+        RST     10H             ; CALBAS
+        DEFW    $0010           ; main PRINT-A
+        JR      <A href="#L1818">L1818</a>           ; back to M-AGAIN
+<a name="L1832"></a>;; <b>MOVE-EOF</b>
+L1832:  RES     4,(IY+$7C)      ; sv FLAGS_3
+        LD      HL,($5C4F)      ; sv CHANS
+        PUSH    HL
+        CALL    <A href="#L059F">L059F</a>           ; routine EX-D-STR
+        CALL    <A href="#L18A8">L18A8</a>           ; routine CL-CHAN
+        CALL    <A href="#L059F">L059F</a>           ; routine EX-D-STR
+        POP     DE
+        LD      HL,($5C4F)      ; sv CHANS
+        OR      A
+        SBC     HL,DE
+        LD      DE,($5CDA)      ; sv N_STR1
+        ADD     HL,DE
+        LD      ($5CDA),HL      ; sv N_STR1
+        CALL    <A href="#L18A8">L18A8</a>           ; routine CL-CHAN
+        CALL    <A href="#L17B7">L17B7</a>           ; routine RCL-T-CH
+        RET                     ; RETURN
+; ---------------------------------------------
+; THE <b><font color=#333388>'USE STREAM OR TEMPORARY CHANNEL'</font></b> ROUTINE
+; ---------------------------------------------
+;
+<a name="L1859"></a>;; <b>OP-STRM</b>
+L1859:  LD      A,($5CD8)       ; sv D_STR1
+        INC     A
+        JR      Z,<A href="#L186A">L186A</a>         ; forward to OP-CHAN
+        DEC     A
+        RST     10H             ; CALBAS
+        DEFW    $1601           ; main CHAN-OPEN
+        LD      HL,($5C51)      ; sv CURCHL
+        LD      ($5CDA),HL      ; sv N_STR1
+        RET
+<a name="L186A"></a>;; <b>OP-CHAN</b>
+L186A:  LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $4D             ; is character "M" ?
+        JR      NZ,<A href="#L1883">L1883</a>        ; forward to CHECK-N
+        CALL    <A href="#L1B05">L1B05</a>           ; routine OP-TEMP-M creates a temporary
+                                ; microdrive channel, starts motor, and
+                                ; fetches record zero of named file.
+        XOR     A
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE
+        LD      ($5CDA),IX      ; sv N_STR1
+        BIT     2,(IX+$43)      ; RECFLG
+        RET     Z
+        RST     20H             ; Shadow Error Restart
+        DEFB    $16             ; Wrong file type
+<a name="L1883"></a>;; <b>CHECK-N</b>
+L1883:  CP      $4E             ; is character "N" ?
+        JR      NZ,<A href="#L188F">L188F</a>        ; forward to CHECK-R
+        CALL    <A href="#L0F46">L0F46</a>           ; routine OP-TEMP-N
+        LD      ($5CDA),IX      ; sv N_STR1
+        RET
+; ---
+;   Finally, check for the RS232 channel before producing an error.
+<a name="L188F"></a>;; <b>CHECK-R</b>
+L188F:  CP      $54             ; is character "T" ?
+        JR      Z,<A href="#L1899">L1899</a>         ; forward to USE-R
+        CP      $42             ; is character "B" ?
+        JR      Z,<A href="#L1899">L1899</a>         ; forward to USE-R
+        RST     20H             ; Shadow Error Restart
+        DEFB    $00             ; Nonsense in BASIC
+; ---
+<a name="L1899"></a>;; <b>USE-R</b>
+L1899:  CALL    <A href="#L0B17">L0B17</a>           ; routine OP-RS-CH
+        LD      ($5CDA),DE      ; sv N_STR1
+        PUSH    DE              ;
+        POP     IX              ;
+        SET     7,(IX+$04)      ; channel letter
+        RET                     ; return.
+; ----------------------------------
+; THE <b><font color=#333388>'CLOSE '</font></b>MOVE' CHANNEL' ROUTINE
+; ----------------------------------
+;
+<a name="L18A8"></a>;; <b>CL-CHAN</b>
+L18A8:  LD      A,($5CD8)       ; sv D_STR1
+        INC     A
+        RET     NZ
+        LD      A,($5CD9)       ; sv L_STR1 device letter.
+        CP      $4D             ; is character "M" ?
+        JR      NZ,<A href="#L18BC">L18BC</a>        ; forward to CL-CHK-N
+        LD      IX,($5CDA)      ; sv N_STR1
+        CALL    <A href="#L138E">L138E</a>           ; routine CLOSE-M2
+        RET                     ;
+<a name="L18BC"></a>;; <b>CL-CHK-N</b>
+L18BC:  CP      $4E             ; is character "N" ?
+        RET     NZ              ;
+        LD      IX,($5CDA)      ; sv N_STR1
+        LD      ($5C51),IX      ; sv CURCHL
+        CALL    <A href="#L0FAE">L0FAE</a>           ; routine SEND-NEOF
+        RET
+; ---------------------------------------------
+; THE <b><font color=#333388>'SAVE DATA BLOCK INTO MICRODRIVE'</font></b> ROUTINE
+; ---------------------------------------------
+;
+<a name="L18CB"></a>;; <b>SA-DRIVE</b>
+L18CB:  LD      A,($5CD6)       ; fetch drive number from D_STR1
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE starts motor.
+        IN      A,($EF)         ; read microdrive port.
+        AND     $01             ; isolate 'write protect' bit.
+        JR      NZ,<A href="#L18D9">L18D9</a>        ; forward, if not low, to STAR-SA
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0E             ; 'Drive 'write' protected'
+; ---
+<a name="L18D9"></a>;; <b>STAR-SA</b>
+L18D9:  LD      HL,($5CE9)      ; sv HD_0D
+        LD      ($5CE4),HL      ; sv D_STR2
+        CALL    <A href="#L1B05">L1B05</a>           ; routine OP-TEMP-M creates a temporary
+                                ; microdrive channel, starts motor, and
+                                ; attempts to fetch record zero of named file.
+        BIT     0,(IX+$18)      ; test CHFLAG
+        JR      NZ,<A href="#L18ED">L18ED</a>        ; forward, with no existing file, to NEW-NAME
+        CALL    <A href="#L138E">L138E</a>           ; routine CLOSE-M2 closes temporary channel
+                                ; and stops the motor.
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0C             ; Writing to a 'read' file
+; ---
+<a name="L18ED"></a>;; <b>NEW-NAME</b>
+L18ED:  SET     2,(IX+$43)      ; update RECFLG signal not a PRINT type file.
+;   <font color=#9900FF>Note.</font> the microdrive motor has been left running by OP-TEMP-M so the next
+;   two lines are not necessary.  Redundant code elsewhere suggests that
+;   OP-TEMP-M once stopped the drive.
+        LD      A,(IX+$19)      ; fetch drive from CHDRIV.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE stops and then restarts the
+                                ; motor.
+        PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0052        ; prepare offset to data buffer.
+        ADD     HL,DE           ; add to address start of data.
+        EX      DE,HL           ; transfer this destination to DE.
+        LD      HL,$5CE6        ; set source to the nine byte header at HD_00
+        LD      BC,$0009        ; nine bytes to copy.
+        LD      (IX+$0B),C      ; update CHBYTE_lo with length saved so far.
+        LDIR                    ; block move the header info into the buffer.
+        PUSH    DE              ; save destination.
+;   Now calculate the number of sectors required using a similar method to
+;   the one used for calculating the number of records to load.
+;   <font color=#9900FF>Note.</font> there is an error in the calculation as one byte should be subtracted
+;   from the total bytes to ensure that there is at least one byte in the EOF
+;   record. The next instruction should be to load HL with eight.
+L190B:  LD      HL,$0009        ; start with the nine header bytes. ??
+        LD      BC,($5CE7)      ; fetch data length from HD_0B.
+        ADD     HL,BC           ; add to give total size of block.
+        SRL     H               ; halve MSB to convert to 512 byte chunks.
+        INC     H               ; increment to include EOF block. Wrong.
+;   <font color=#9900FF>Note.</font>
+;   511  bytes = 502 bytes + 9 header = $01FF, SRL=$00, INC=$01 sectors OK.
+;   512  bytes = 503 bytes + 9 header = $0200, SRL=$01, INC=$02 sectors WRONG!!
+;   513  bytes = 504 bytes + 9 header = $0201, SRL=$01, INC=$02 sectors OK.
+        PUSH    HL              ; preserve register H the sector counter.
+        CALL    <A href="#L1D43">L1D43</a>           ; routine FREESECT calculates free sectors on
+                                ; cartridge.
+        POP     HL              ; bring back the sector estimate in H.
+        LD      A,E             ; load accumulator with actual sectors.
+        CP      H               ; compare with estimate
+        JR      NC,<A href="#L1921">L1921</a>        ; forward, if equal or greater, to SA-DRI-2
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0F             ; 'Microdrive full'
+; ---
+<a name="L1921"></a>;; <b>SA-DRI-2</b>
+L1921:  POP     DE              ; bring back destination.
+        LD      HL,($5CE4)      ; fetch start from D_STR2
+        LD      BC,($5CE7)      ; fetch data length from HD_0B
+<a name="L1929"></a>;; <b>SA-DRI-3</b>
+L1929:  LD      A,B             ; test for
+        OR      C               ; zero bytes.
+        JR      Z,<A href="#L194F">L194F</a>         ; forward, if all chunks saved, to SA-DRI-4
+        LD      A,(IX+$0C)      ; fetch high byte of byte counter from CHBYTE_hi
+        CP      $02             ; compare to 2 which would indicate 512 bytes.
+        JR      NZ,<A href="#L1943">L1943</a>        ; forward, if less, to SA-DRI-WR
+; a sector is written to microdrive.
+        PUSH    HL              ; preserve start of data.
+        PUSH    BC              ; preserve length.
+        CALL    <A href="#L12EE">L12EE</a>           ; routine WRITE-PRC.
+        POP     BC              ; restore length.
+        PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0052        ; add offset to
+        ADD     HL,DE           ; point to data buffer.
+        EX      DE,HL           ; transfer this destination to DE.
+        POP     HL              ; restore the start of data.
+<a name="L1943"></a>;; <b>SA-DRI-WR</b>
+L1943:  LDI                     ; transfer one byte at a time decrementing BC
+                                ; the total byte counter.
+;   now increment the channel byte counter which started at zero and has a
+;   limit of 512 bytes.
+        INC     (IX+$0B)        ; increment CHBYTE_lo
+        JR      NZ,<A href="#L1929">L1929</a>        ; back, if not 256, to SA-DRI-3
+        INC     (IX+$0C)        ; increment CHBYTE_hi
+        JR      <A href="#L1929">L1929</a>           ; back to SA-DRI-3 to check high byte.
+; ---
+<a name="L194F"></a>;; <b>SA-DRI-4</b>
+L194F:  SET     1,(IX+$43)      ; update RECFLG mark this as EOF record.
+        CALL    <A href="#L12EE">L12EE</a>           ; routine WRITE-PRC writes last record in set.
+        LD      A,($5CEF)       ; fetch user-alterable system variable COPIES
+        DEC     A               ; decrement
+        JR      Z,<A href="#L196A">L196A</a>         ; forward, if zero, to END-SA-DR
+        LD      ($5CEF),A       ; place decremented value back in COPIES
+        RES     1,(IX+$43)      ; update RECFLG - signal not the EOF record.
+        LD      A,$00           ; prepare to start saving at record zero again.
+        LD      (IX+$0D),A      ; update the channel record counter CHREC.
+        JR      <A href="#L18ED">L18ED</a>           ; back to NEW-NAME
+; ---
+<a name="L196A"></a>;; <b>END-SA-DR</b>
+L196A:  XOR     A               ; set accumulator to zero.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE stops the motor.
+        JP      <A href="#L119F">L119F</a>           ; jump to DEL-M-BUF
+; ----------------------------------------------------
+; THE <b><font color=#333388>'GET HEADER INFORMATION FROM MICRODRIVE'</font></b> ROUTINE
+; ----------------------------------------------------
+; this routine extracts the nine bytes of global header information that
+; is prepended to the data saved on microdrive. This relates to the type -
+; Basic, Code and length etc. and is the equivalent of a tape header without
+; the name which, in contrast, does have to be saved to every record.
+; It is obtained therefore from the start of data at record zero.
+;
+; <font color=#9900FF>Note.</font> the destination for this data, (program area or variable location),
+; has already been calculated and since opening a channel will move this
+; destination up in memory, the "Start of data" is transferred to the D_STR2
+; location, otherwise used for the second filename during moves, so that its
+; value is adjusted by REST-N-AD during OP-TEMP-M.
+<a name="L1971"></a>;; <b>F-M-HEAD</b>
+L1971:  LD      HL,($5CE1)      ; copy start of data from D_STR2(+3)
+        LD      ($5CE4),HL      ; to dynamic location D_STR2(+6)
+        CALL    <A href="#L1B05">L1B05</a>           ; routine OP-TEMP-M creates a temporary
+                                ; microdrive channel, starts motor, and
+                                ; fetches record zero of named file.
+        BIT     0,(IX+$18)      ; test CHFLAG for valid first record.
+        JR      Z,<A href="#L1982">L1982</a>         ; forward, if OK, to F-HD-2
+        RST     20H             ; Shadow Error Restart
+        DEFB    $11             ; 'File not found'
+; ---
+<a name="L1982"></a>;; <b>F-HD-2</b>
+L1982:  BIT     2,(IX+$43)      ; test RECFLG is it a print file
+        JR      NZ,<A href="#L198A">L198A</a>        ; forward, if not, to F-HD-3
+        RST     20H             ; Shadow Error Restart
+        DEFB    $16             ; 'Wrong file type'
+; ---
+<a name="L198A"></a>;; <b>F-HD-3</b>
+L198A:  PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0052        ; offset to CHDATA
+        ADD     HL,DE           ; add to address start of data.
+        LD      DE,$5CE6        ; set destination to nine system variables
+                                ; starting at location HD_00.
+        LD      BC,$0009        ; nine bytes to copy.
+        LDIR                    ; block move to HD_00 - HD_11.
+        RET                     ; return.
+; --------------------------------------------------
+; THE <b><font color=#333388>'LOAD OR VERIFY BLOCK FROM MICRODRIVE'</font></b> ROUTINE
+; --------------------------------------------------
+;   This subroutine is called once only from LV-ANY to load a block of code,
+;   previously SAVED to a number of sectors, from microdrive.
+;   At this stage a temporary channel has already been created and it holds
+;   the first 512 byte record containing at the start the nine header bytes.
+;   There will be an accurate microdrive map for the drive which has its
+;   motor running.
+;   The block could be a program, code bytes or an array and the first
+;   receiving location is in HL and the length in DE.
+<a name="L199A"></a>;; <b>LV-MCH</b>
+L199A:  LD      ($5CE9),HL      ; save start in system variable HD_0D
+;   now directly read the header values at the start of the data buffer.
+        LD      E,(IX+$53)      ; directly read the saved length
+        LD      D,(IX+$54)      ; from the data buffer into DE.
+;   now calculate how many 512 byte microdrive records need to be read in
+;   by taking the total minus one to ensure an EOF record.
+;   e.g.
+;   1023 bytes = 1014 bytes + 9 header - 1 = $03FE, SRL=$01, INC=$02 sectors
+;   1024 bytes = 1015 bytes + 9 header - 1 = $03FF, SRL=$01, INC=$02 sectors
+;   1025 bytes = 1016 bytes + 9 header - 1 = $0400, SRL=$02, INC=$03 sectors
+        LD      HL,$0008        ; add eight in effect +9 for header -1.
+        ADD     HL,DE           ; add the program/code length.
+;   the MSB is the number of 256 chunks.
+        SRL     H               ; shift right to halve and give 512 byte
+                                ; chunks.
+        INC     H               ; increment to include the extra sector.
+        LD      A,H             ; use accumulator to store record count
+        LD      ($5CE7),A       ; in the temporary system variable HD_0B
+;   the microdrive map is now saved on the machine stack, for later recall,
+;   and at the same time the current map locations are all set to zero.
+;   The new map is to be used for records rather than sectors.
+        CALL    <A href="#L1A04">L1A04</a>           ; routine SA-MAP saves the thirty two bytes
+                                ; of the map on the machine stack safely
+                                ; dipping into the 80 bytes of spare memory.
+;   now, since this is record zero, subtract the nine header bytes from the
+;   current record length and put back.
+        LD      DE,$0009        ;
+        LD      L,(IX+$45)      ; RECLEN_lo
+        LD      H,(IX+$46)      ; RECLEN_hi
+        OR      A               ; clear carry
+        SBC     HL,DE           ;
+        LD      (IX+$45),L      ; RECLEN_lo
+        LD      (IX+$46),H      ; RECLEN_hi
+;
+        PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$005B        ; prepare offset $0052 to data and then an
+        ADD     HL,DE           ; extra nine bytes. Add to skip the header.
+        LD      DE,($5CE9)      ; set destination from HD_0D
+        JR      <A href="#L19EA">L19EA</a>           ; forward to LOOK-MAP to enter the record
+                                ; loading loop at the mid-point as record
+                                ; zero is already in the channel.
+; ---
+;   The record loading loop loads records in random order.  Consider that
+;   multiple copies of a filename may have been saved so there may be several
+;   sectors with the same record number.
+<a name="L19D0"></a>;; <b>USE-REC</b>
+L19D0:  CALL    <A href="#L1A5D">L1A5D</a>           ; routine F-REC2 fetches only a header and
+                                ; record that matches the name specified
+                                ; in CHNAME and only if the map bit is reset
+                                ; indicating no sector with this record number
+                                ; has already been loaded.
+        LD      A,(IX+$44)      ; re-fetch record number from RECNUM.
+; <font color=#9900FF>Note.</font> the next test is a nonsense as a record zero has already been marked
+; so no sector with record zero could be reloaded.
+        OR      A               ; test for a record zero.
+        JR      Z,<A href="#L19D0">L19D0</a>         ; back, if so, to USE-REC.
+; now calculate the destination if this 512 byte sector.
+        RLA                     ; double recnum to give 512 byte chunks
+        DEC     A               ; decrement to adjust for nine bytes of header.
+        LD      D,A             ; place in MSB of offset
+        LD      E,$F7           ; set LSB of offset to $00 - $09 for header.
+        LD      HL,($5CE9)      ; fetch start of data from HD_0D
+        ADD     HL,DE           ; add to calculate destination for this sector.
+        EX      DE,HL           ; transfer destination to DE.
+        PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      BC,$0052        ; prepare offset to start of 512 byte buffer
+        ADD     HL,BC           ; add so that HL addresses start of data.
+; -&gt; The mid loop entry point.
+<a name="L19EA"></a>;; <b>LOOK-MAP</b>
+L19EA:  EXX                     ; preserve HL and DE by using alternate
+                                ; registers.
+        CALL    <A href="#L13BF">L13BF</a>           ; routine CHK-MAP-2 sets HL to the map byte
+                                ; and B to the mask.
+; <font color=#9900FF>Note.</font> the routine also resets the zero flag if this record has previously
+; been loaded but this is not possible.
+        JR      NZ,<A href="#L19D0">L19D0</a>        ; back, if already loaded, to USE-REC.
+;   since this is the first time for this record mark so that not loaded again.
+        LD      A,(HL)          ; mark the record bit
+        OR      B               ; by setting it so that it is not
+        LD      (HL),A          ; considered for loading again.
+        EXX                     ; restore HL (source) and DE (destination).
+        CALL    <A href="#L1A39">L1A39</a>           ; routine LD-VE-M loads or verifies a
+                                ; data record.
+;   now decrement the record count which is beyond reach of IY register.
+        LD      A,($5CE7)       ; fetch count of records to be loaded HD_0B
+        DEC     A               ; decrement
+        LD      ($5CE7),A       ; and place back in system variable HD_0B
+        JR      NZ,<A href="#L19D0">L19D0</a>        ; back, if not finished to USE-REC
+;   the block is loaded
+        CALL    <A href="#L1A1E">L1A1E</a>           ; routine RE-MAP restores the true microdrive
+                                ; map from the stack.
+        RET                     ; return.
+; ------------------------------------------
+; THE <b><font color=#333388>'SAVE MICRODRIVE MAP CONTENTS'</font></b> ROUTINE
+; ------------------------------------------
+;   This routine saves the sector-mapped microdrive map on the machine stack
+;   at the same time setting each of the 32 vacated locations to zero.
+<a name="L1A04"></a>;; <b>SA-MAP</b>
+L1A04:  POP     HL              ; drop the return address into HL
+        LD      ($5CC9),HL      ; and save in unused system variable SECTOR
+        LD      L,(IX+$1A)      ; fetch address of microdrive map from CHMAP
+        LD      H,(IX+$1B)      ; fetch address of microdrive map from CHMAP
+        LD      BC,$1000        ; set word counter B to sixteen and C to zero.
+;   now enter a loop stacking two bytes at a time.
+<a name="L1A11"></a>;; <b>SA-MAP-LP</b>
+L1A11:  LD      E,(HL)          ; fetch first byte to E.
+        LD      (HL),C          ; set location to zero.
+        INC     HL              ; bump address.
+        LD      D,(HL)          ; fetch second byte to D.
+        LD      (HL),C          ; set location to zero.
+        INC     HL              ; bump address.
+        PUSH    DE              ; save DE on machine stack.
+        DJNZ    <A href="#L1A11">L1A11</a>           ; back, for 16 pairs, to SA-MAP-LP
+        LD      HL,($5CC9)      ; restore return address from SECTOR
+        JP      (HL)            ; and jump to location.
+; ---------------------------------------------
+; THE <b><font color=#333388>'RESTORE MICRODRIVE MAP CONTENTS'</font></b> ROUTINE
+; ---------------------------------------------
+;   This routine is the opposite of the above and restores the sector-mapped
+;   microdrive map from the machine stack back to its original location
+;   overwriting the now redundant record-indicating map.
+<a name="L1A1E"></a>;; <b>RE-MAP</b>
+L1A1E:  POP     HL              ; drop the subroutine return address.
+        LD      ($5CC9),HL      ; store in the multi-purpose variable SECTOR.
+        LD      L,(IX+$1A)      ; fetch address of microdrive map from CHMAP.
+        LD      H,(IX+$1B)      ; fetch address of microdrive map from CHMAP.
+        LD      DE,$001F        ; thirty one locations are added.
+        ADD     HL,DE           ; to address the last location.
+        LD      B,$10           ; set the pop counter to sixteen.
+<a name="L1A2E"></a>;; <b>RE-MAP-LP</b>
+L1A2E:  POP     DE              ; pop two bytes of the map from the stack.
+        LD      (HL),D          ; insert a map byte.
+        DEC     HL              ; decrement the address.
+        LD      (HL),E          ; insert second map byte.
+        DEC     HL              ; decrement the address again.
+        DJNZ    <A href="#L1A2E">L1A2E</a>           ; back, sixteen times, to RE-MAP-LP.
+        LD      HL,($5CC9)      ; restore the return address from SECTOR.
+        JP      (HL)            ; and jump to address.
+; ---------------------
+; THE <b><font color=#333388>'LD-VE-M'</font></b> ROUTINE
+; ---------------------
+;   The Load or Verify from Microdrive routine.
+;   This routine loads or verifies up to 512 bytes of data currently in the
+;   microdrive channel data buffer.
+<a name="L1A39"></a>;; <b>LD-VE-M</b>
+L1A39:  LD      C,(IX+$45)      ; RECLEN_lo
+        LD      B,(IX+$46)      ; RECLEN_hi
+; now test if a VERIFY operation by performing the equivalent of bit 7,(iy+$7c)
+        LD      A,($5CB6)       ; load system variable FLAGS_3 to accumulator.
+        BIT     7,A             ; test FLAGS_3 value - performing VERIFY ?
+        JR      NZ,<A href="#L1A49">L1A49</a>        ; forward, if so, to VE-M-E
+;   the operation is a LOAD.
+        LDIR                    ; block copy the bytes.
+        RET                     ; return.
+; ---
+;   the operation is a VERIFY.
+<a name="L1A49"></a>;; <b>VE-M-E</b>
+L1A49:  LD      A,(DE)          ; fetch a byte from the destination.
+        CP      (HL)            ; compare to that of source
+        JR      NZ,<A href="#L1A55">L1A55</a>        ; forward, with mismatch, to VE-FAIL
+        INC     HL              ; increment source address.
+        INC     DE              ; increment destination address.
+        DEC     BC              ; decrement byte count.
+        LD      A,B             ; test for
+        OR      C               ; zero.
+        JR      NZ,<A href="#L1A49">L1A49</a>        ; back, if not, to VE-M-E
+        RET                     ; return.
+; ---
+<a name="L1A55"></a>;; <b>VE-FAIL</b>
+L1A55:  RST     20H             ; Shadow Error Restart
+        DEFB    $15             ; 'Verification has failed'
+; ------------------------------------------
+; THE <b><font color=#333388>'FETCH RECORD FROM MICRODRIVE'</font></b> ROUTINE
+; ------------------------------------------
+;   Entered at F-REC2,
+;   <font color=#9900FF>Note.</font> the first entry point f-rec1 is unused.
+<a name="L1A57"></a>;; <b>f-rec1</b>
+L1A57:  LD      A,(IX+$19)      ; fetch drive number.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE starts motor.
+; --&gt;
+<a name="L1A5D"></a>;; <b>F-REC2</b>
+L1A5D:  LD      BC,$04FB        ; Set sector counter to 5 * 255 = 1275
+        LD      ($5CC9),BC      ; Update System Variable SECTOR
+<a name="L1A64"></a>;; <b>UNTILFIVE</b>
+L1A64:  CALL    <A href="#L1280">L1280</a>           ; routine G-HD-RC fetches the next header and
+                                ; matching record to pass tape head.
+        JR      C,<A href="#L1A7B">L1A7B</a>         ; forward, with name mismatch, to F-ERROR
+        JR      Z,<A href="#L1A7B">L1A7B</a>         ; forward, with unused record, to F-ERROR
+        CALL    <A href="#L13BF">L13BF</a>           ; routine CHK-MAP-2  checks RECORD.
+        JR      NZ,<A href="#L1A7B">L1A7B</a>        ; forward, if already loaded, to F-ERROR
+        PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0052        ;
+        ADD     HL,DE           ;
+        CALL    <A href="#L142B">L142B</a>           ; routine CHKS-BUFF
+        RET     Z               ;
+<a name="L1A7B"></a>;; <b>F-ERROR</b>
+L1A7B:  CALL    <A href="#L13F7">L13F7</a>           ; routine DEC-SECT
+        JR      NZ,<A href="#L1A64">L1A64</a>        ; back to UNTILFIVE
+        RST     20H             ; Shadow Error Restart
+        DEFB    $11             ; File not found
+; -----------------------------------------
+; THE <b><font color=#333388>'RESTORE ADDRESS OF FILENAME'</font></b> ROUTINE
+; -----------------------------------------
+;   This subroutine performs a similar function to the Main ROM POINTERS routine
+;   by adjusting the extra system variables that point to filenames within
+;   the sliding, dynamic areas.
+;   On entry HL points to the start of the New Room and BC holds the number of
+;   bytes created.
+<a name="L1A82"></a>;; <b>REST-N-AD</b>
+L1A82:  PUSH    HL              ; Preserve HL throughout.
+        PUSH    HL              ; Preserve HL for second call.
+        LD      DE,($5CE4)      ; Fetch D_STR2 - start of 2nd filename.
+        CALL    <A href="#L1A9D">L1A9D</a>           ; routine TST-PLACE may adjust fetched value.
+        LD      ($5CE4),DE      ; Store in System Variable  D_STR2
+        POP     HL              ; Restore HL for second call.
+        LD      DE,($5CDC)      ; Fetch D_STR1 - start of 1st filename.
+        CALL    <A href="#L1A9D">L1A9D</a>           ; routine TST-PLACE
+        LD      ($5CDC),DE      ; Store in System Variable D_STR1
+        POP     HL              ; Restore original HL value.
+        RET                     ; return.
+; ---------------------------
+; THE <b><font color=#333388>'TEST PLACE'</font></b> SUBROUTINE
+; ---------------------------
+;   This subroutine is used twice from above to test if the filename address
+;   is within the Spectrum's dynamic RAM area.
+;   HL = location before new room.
+;   DE = address of filename.
+;   BC = amount of room just created.
+<a name="L1A9D"></a>;; <b>TST-PLACE</b>
+L1A9D:  SCF                     ; adjust for one before.
+        SBC     HL,DE           ; subtract filename address from start of room
+        RET     NC              ; and if before new room then return.
+        LD      HL,($5C65)      ; fetch STKEND and if the filename is above
+        SBC     HL,DE           ; then it is not in dynamic memory.
+        RET     C               ;
+        EX      DE,HL           ; add the number of bytes created
+        ADD     HL,BC           ; to the filename address
+        EX      DE,HL           ; to bring it into line.
+        RET                     ; return.
+; -----------------------------------
+; THE <b><font color=#333388>'CALLS TO THE COMMANDS'</font></b> ROUTINE
+; -----------------------------------
+;
+<a name="L1AAB"></a>;; <b>ERASE-RUN</b>
+L1AAB:  CALL    <A href="#L1D79">L1D79</a>           ; routine ERASE
+        JR      <A href="#L1AC9">L1AC9</a>           ; forward to ENDC
+; ---
+<a name="L1AB0"></a>;; <b>MOVE-RUN</b>
+L1AB0:  CALL    <A href="#L17F5">L17F5</a>           ; routine MOVE
+        JR      <A href="#L1AC9">L1AC9</a>           ; forward to ENDC
+; ---
+<a name="L1AB5"></a>;; <b>CAT-RUN</b>
+L1AB5:  CALL    <A href="#L1C52">L1C52</a>           ; routine CAT
+        JR      <A href="#L1AC9">L1AC9</a>           ; forward to ENDC
+; ---
+<a name="L1ABA"></a>;; <b>FOR-RUN</b>
+L1ABA:  CALL    <A href="#L1B5D">L1B5D</a>           ; routine FORMAT
+        JR      <A href="#L1AC9">L1AC9</a>           ; forward to ENDC
+; ---
+<a name="L1ABF"></a>;; <b>OP-RUN</b>
+L1ABF:  CALL    <A href="#L1ACC">L1ACC</a>           ; routine OP-M-STRM
+        JR      <A href="#L1AC9">L1AC9</a>           ; forward to ENDC
+; ---
+<a name="L1AC4"></a>;; <b>SAVE-RUN</b>
+L1AC4:  CALL    <A href="#L18CB">L18CB</a>           ; routine SA-DRIVE
+        JR      <A href="#L1AC9">L1AC9</a>           ; forward to ENDC
+; ---
+<a name="L1AC9"></a>;; <b>ENDC</b>
+L1AC9:  JP      <A href="#L05C1">L05C1</a>           ; jump to END1
+; ------------------------------------------
+; THE <b><font color=#333388>'OPEN A PERMANENT "M" CHANNEL'</font></b> ROUTINE
+; ------------------------------------------
+;
+<a name="L1ACC"></a>;; <b>OP-M-STRM</b>
+L1ACC:  LD      A,($5CD8)       ; sv D_STR1
+        ADD     A,A             ;
+        LD      HL,$5C16        ; sv STRMS_00
+        LD      E,A             ;
+        LD      D,$00           ;
+        ADD     HL,DE           ;
+        PUSH    HL              ;
+        CALL    <A href="#L1B05">L1B05</a>           ; routine OP-TEMP-M creates a temporary
+                                ; microdrive channel, starts motor, and
+                                ; fetches record zero of named file.
+        BIT     0,(IX+$18)      ; CHFLAG
+        JR      Z,<A href="#L1AE9">L1AE9</a>         ; forward to MAKE-PERM
+        IN      A,($EF)         ;
+        AND     $01             ; isolate write prot.
+        JR      NZ,<A href="#L1AE9">L1AE9</a>        ; forward to MAKE-PERM
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0E             ; Drive 'write' protected
+; ---
+<a name="L1AE9"></a>;; <b>MAKE-PERM</b>
+L1AE9:  RES     7,(IX+$04)      ; channel letter
+        XOR     A               ;
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE
+        BIT     0,(IX+$18)      ; CHFLAG
+        JR      NZ,<A href="#L1AFF">L1AFF</a>        ; forward to STORE-DSP
+        BIT     2,(IX+$43)      ; RECFLG
+        JR      Z,<A href="#L1AFF">L1AFF</a>         ; forward to STORE-DSP
+        RST     20H             ; Shadow Error Restart
+        DEFB    $16             ; Wrong file type
+; ---
+<a name="L1AFF"></a>;; <b>STORE-DSP</b>
+L1AFF:  EX      DE,HL           ;
+        POP     HL              ;
+        LD      (HL),E          ;
+        INC     HL              ;
+        LD      (HL),D          ;
+        RET                     ;
+; ------------------------------------------
+; THE <b><font color=#333388>'OPEN A TEMPORARY "M" CHANNEL'</font></b> ROUTINE
+; ------------------------------------------
+; <font color=#339933>(Hook Code: $22)</font>
+;
+<a name="L1B05"></a>;; <b>OP-TEMP-M</b>
+L1B05:  CALL    <A href="#L10A5">L10A5</a>           ; routine SET-T-MCH creates a temporary channel
+                                ; using either an existing microdrive map from
+                                ; a channel also using this drive or allocating
+                                ; a new one initialized to $FF bytes.
+                                ; fields CHREC etc. are set to zero.
+        PUSH    HL              ; preserve the offset to this channel from CHANS
+        LD      A,(IX+$19)      ; fetch drive number 1 - 8 from CHDRIV
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE starts motor and disables
+                                ; interrupts.
+        LD      BC,$0032        ; now set temporary unused
+        LD      ($5CC9),BC      ; system variable SECTOR_lo to fifty
+                                ; and set SECTOR_hi to zero.
+; now enter a loop
+<a name="L1B16"></a>;; <b>OP-F-L</b>
+L1B16:  CALL    <A href="#L1280">L1280</a>           ; routine G-HD-RC fetches any header and
+                                ; matching record
+        PUSH    AF              ; preserve return status flags.
+; maintain the 'maximum sectors to visit' so only one rotation of tape occurs.
+        LD      A,(IX+$29)      ; fetch sector from HDNUMB
+        ADD     A,$03           ; add 3
+        LD      HL,$5CC9        ; address current (max+3) in SECTOR_lo
+        CP      (HL)            ; compare
+        JR      C,<A href="#L1B26">L1B26</a>         ; forward, if less, to OP-F-X
+        LD      (HL),A          ; update with new max sectors to visit.
+<a name="L1B26"></a>;; <b>OP-F-X</b>
+L1B26:  POP     AF              ; restore status flags.
+        JR      C,<A href="#L1B49">L1B49</a>         ; forward, with no name match, to OP-F-4
+        JR      Z,<A href="#L1B46">L1B46</a>         ; forward, if unused, to OP-F-3
+                                ; to reset map bit.
+; the fetched record is one from the file named in CHNAME
+        RES     0,(IX+$18)      ; update CHFLAG to indicate success.
+        LD      A,(IX+$44)      ; fetch the record number within file RECNUM
+        OR      A               ; test for zero - first record.
+        JR      NZ,<A href="#L1B41">L1B41</a>        ; forward, if not, to OP-F-2
+        PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0052        ; prepare offset to data and
+        ADD     HL,DE           ; add to address start of the 512 byte buffer
+        CALL    <A href="#L142B">L142B</a>           ; routine CHKS-BUFF checks that checksum agrees.
+        JR      Z,<A href="#L1B5B">L1B5B</a>         ; forward, if OK, to DP-F-5
+<a name="L1B41"></a>;; <b>OP-F-2</b>
+L1B41:  CALL    <A href="#L1258">L1258</a>           ; routine GET-R-2 repeatedly calls the
+                                ; subroutine G-HD-RC (as at start of loop)
+                                ; until the validated record matching CHREC
+                                ; (zero) is loaded.
+        JR      <A href="#L1B5B">L1B5B</a>           ; forward, with success, to DP-F-5.
+; ---
+<a name="L1B46"></a>;; <b>OP-F-3</b>
+L1B46:  CALL    <A href="#L13E3">L13E3</a>           ; routine RES-B-MAP resets bit for unused
+                                ; sectors.
+; the branch was here
+<a name="L1B49"></a>;; <b>OP-F-4</b>
+L1B49:  LD      HL,$5CCA        ; address visited sector count SECTOR_hi
+        LD      A,(HL)          ; fetch sector counter.
+        INC     A               ; increment
+        LD      (HL),A          ; and put back in SECTOR_hi.
+        DEC     HL              ; address the max sector value.
+        CP      (HL)            ; compare.
+        JR      C,<A href="#L1B16">L1B16</a>         ; back, if less than one revolution, to OP-F-L
+; else a full revolution occurred without finding the record.
+        RES     1,(IX+$43)      ; RECFLG
+        RES     2,(IX+$43)      ; RECFLG
+; the branch was here with record zero of named file.
+<a name="L1B5B"></a>;; <b>DP-F-5</b>
+L1B5B:  POP     HL              ; restore the offset from CHANS.
+        RET                     ; return.
+; --------------------------------
+; THE <b><font color=#333388>'FORMAT "M" COMMAND'</font></b> ROUTINE
+; --------------------------------
+; e.g. FORMAT "m";1;"demos"
+<a name="L1B5D"></a>;; <b>FORMAT</b>
+L1B5D:  CALL    <A href="#L10A5">L10A5</a>           ; routine SET-T-MCH creates a temporary
+                                ; microdrive channel with name of cartridge.
+        LD      A,(IX+$19)      ; fetch drive number from CHDRIV
+        CALL    <A href="#L1565">L1565</a>           ; routine SW-MOTOR starts the motor.
+        LD      BC,$32C8        ; decimal 1300
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC
+        DI                      ; Disable Interrupts.
+        IN      A,($EF)         ; read microdrive port.
+        AND     $01             ; isolate write prot. bit.
+        JR      NZ,<A href="#L1B75">L1B75</a>        ; forward, if not low, to FORMAT-1
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0E             ; Drive 'write' protected
+; ---
+<a name="L1B75"></a>;; <b>FORMAT-1</b>
+L1B75:  LD      A,$E6           ; enable writing.
+        OUT     ($EF),A         ; update microdrive port.
+        LD      BC,$00FF        ; assume 255 sectors will fit on a tape.
+        LD      ($5CC9),BC      ; set system variable SECTOR.
+        PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$002C        ; offset to HDNAME
+        ADD     HL,DE           ;
+        EX      DE,HL           ; make destination HDNAME
+        LD      HL,$FFE2        ;
+        ADD     HL,DE           ; make source CHNAME
+        LD      BC,$000A        ; ten bytes to copy.
+        LDIR                    ; copy - C is now zero.
+; now prepare an 'unusable' record.
+        XOR     A               ; make accumulator zero.
+        LD      (IX+$47),A      ; set first character of RECNAM to zero.
+        SET     0,(IX+$28)      ; mark HDFLAG indicate a header.
+        RES     0,(IX+$43)      ; mark RECFLG indicate a record.
+        SET     1,(IX+$43)      ; mark RECFLG indicate an EOF record.
+        PUSH    IX              ; transfer the channel base address
+        POP     DE              ; to the DE register pair for a change.
+        LD      HL,$0043        ; offset to RECFLG - start of record descriptor.
+        ADD     HL,DE           ; add offset to start of record descriptor.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R inserts 14 byte checksum.
+;   Now enter a loop to write the blocks to the cartridge
+<a name="L1BAB"></a>;; <b>WR-F-TEST</b>
+L1BAB:  CALL    <A href="#L13F7">L13F7</a>           ; routine DEC-SECT decrements sector originally
+                                ; set to $FF
+        JR      Z,<A href="#L1BDF">L1BDF</a>         ; forward, if BC is zero, to TEST-SCT  -&gt;
+        LD      (IX+$29),C      ; insert reduced sector number in HDNUMB
+        PUSH    IX              ; transfer the base channel address
+        POP     HL              ; to the HL register pair.
+        LD      DE,<A href="#L0028">L0028</a>        ; offset to the header
+        ADD     HL,DE           ; add to address HDFLAG.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R inserts 14 byte checksum
+                                ; preserving the HL value.
+        LD      DE,$FFF4        ; subtract twelve
+        ADD     HL,DE           ; to address the header PREAMBLE.
+        CALL    <A href="#L15AD">L15AD</a>           ; routine OUT-M-HD writes the header to tape.
+        LD      BC,$01B2        ; set timer for gap - 434 decimal.
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC
+        PUSH    IX              ; transfer start of channel
+        POP     HL              ; to HL register pair.
+        LD      DE,$0037        ; adjust HL to point to PREAMBLE at
+        ADD     HL,DE           ; start of record descriptor.
+        CALL    <A href="#L16AF">L16AF</a>           ; routine WR-BLK writes record to tape.
+        LD      BC,$0100        ; a short delay.
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC
+        CALL    <A href="#L163E">L163E</a>           ; routine TEST-BRK
+        JR      <A href="#L1BAB">L1BAB</a>           ; loop back to WR-F-TEST for sectors 254 - 1.
+; ---
+; -&gt; the branch was to here when all sectors from 254 down to 1 have been
+;    written.
+<a name="L1BDF"></a>;; <b>TEST-SCT</b>
+L1BDF:  LD      BC,$0087        ; use value 35 decimal.
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC
+        LD      A,$EE           ; signal disable writing.
+        OUT     ($EF),A         ; output to microdrive port.
+        LD      A,(IX+$19)      ; select drive number from CHDRIV.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE.
+        LD      BC,$0032        ; set max sector to fifty, read sectors to zero.
+        LD      ($5CC9),BC      ; insert both values in SECTOR
+<a name="L1BF6"></a>;; <b>CHK-SCT</b>
+L1BF6:  CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads the next valid header
+                                ; to pass the tape head.
+        LD      A,(IX+$29)      ; fetch the unique sector number from HDNUMB
+        ADD     A,$03           ; add three to value.
+        LD      HL,$5CC9        ; address system variable SECTOR
+        CP      (HL)            ; and compare to total of sectors to visit.
+        JR      C,<A href="#L1C05">L1C05</a>         ; forward if less to CHK-SCT2
+        LD      (HL),A          ; else insert new value for sectors to visit.
+<a name="L1C05"></a>;; <b>CHK-SCT2</b>
+L1C05:  CALL    <A href="#L13C4">L13C4</a>           ; routine CHECK-MAP checks if sector is free
+                                ; on the microdrive map.
+        JR      Z,<A href="#L1C1E">L1C1E</a>         ; forward, if so, to CHK-NSECT
+        PUSH    IX              ; transfer channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0043        ; offset to the start of record descriptor.
+        ADD     HL,DE           ; add to address RECFLG.
+        CALL    <A href="#L165A">L165A</a>           ; routine READ-BLK reads in a block.
+        JR      NZ,<A href="#L1C1E">L1C1E</a>        ; forward, with bad read, to CHK-NSECT
+                                ; leaving map bit set.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R check the header checksum
+        JR      NZ,<A href="#L1C1E">L1C1E</a>        ; forward, with error, to CHK-NSECT
+        CALL    <A href="#L13E3">L13E3</a>           ; routine RES-B-MAP resets the map bit marking
+                                ; the sector as usable.
+<a name="L1C1E"></a>;; <b>CHK-NSECT</b>
+L1C1E:  LD      HL,$5CCA        ; address SECTOR_hi the visited sector counter.
+        LD      A,(HL)          ; fetch the value.
+        INC     A               ; increment
+        LD      (HL),A          ; and place back.
+        DEC     HL              ; decrement to address max sectors to visit.
+        CP      (HL)            ; compare counter to limit.
+        JR      C,<A href="#L1BF6">L1BF6</a>         ; back, if counter is less, to CHK-SCT
+        LD      L,(IX+$1A)      ; load L from CHMAP_lo
+        LD      H,(IX+$1B)      ; load H from CHMAP_hi
+;   Register HL now addresses the microdrive maps which at this stage have
+;   sectors 0 and 255 marked as unusable. If as is usual, the lower numbered
+;   sectors have overwritten the higher numbered sectors then typically
+;   the top seventy sectors, or so, will be marked as unusable though not on an
+;   emulated machine which at this stage will only have 0 and 255 marked
+;   unusable. On a real machine the splice will show up as an unusable sector
+;   and there may be some other sectors unusable due to dirt on the recording
+;   film.
+;   What happens next is unique to this ROM and is no doubt due to extensive
+;   testing and analysis of the microdrives by Sinclair Research.
+;   Microdrive sectors are encountered in descending order, as they are
+;   written, and the following routine marks any sector following a bad sector
+;   as bad also.  One can conclude that Sinclair Research's test programme
+;   revealed that the first sectors to fail were those adjacent to contaminated
+;   or damaged sectors.
+;   This perhaps explains why my use of the microdrives with ROM 2 has been
+;   more reliable than early reviews, no doubt with ROM 1, suggested.
+        LD      DE,$001F        ; add thirty one to start at the end of the map
+        ADD     HL,DE           ; - the byte that refers to sector 255.
+        LD      B,$20           ; count the thirty two bytes of a map.
+        SCF                     ; set carry flag to ensure that sector 255
+                                ; is unusable - but it is already marked so ??
+<a name="L1C35"></a>;; <b>PREP-MARK</b>
+L1C35:  LD      A,(HL)          ; fetch a byte representing eight sectors.
+        LD      C,A             ; and store it in C - <font color=#9900FF>Note.</font> unnecessary.
+        RRA                     ; rotate right accumulator  C-&gt;76543210-&gt;C
+        OR      C               ; combine with original value. Why not OR (HL) ?
+        LD      (HL),A          ; store the modified byte back in the map.
+        DEC     HL              ; point to the next byte for lower-numbered
+                                ; sectors.
+L1C3B:  DJNZ    <A href="#L1C35">L1C35</a>           ; loop back to PREP-MARK for all 32 map bytes.
+;   <font color=#9900FF>Note.</font> the above routine is untidy.  There is no need to set the carry flag
+;   and no need to store the original value in C.  While it achieves it's aims,
+;   if sector one is bad it has no effect on the next sector to be encountered.
+;   That would be hard to implement but the first sector that is marked bad,
+;   the highest numbered sector, is marked so solely because it is adjacent to
+;   the overwritten section.
+;   <font color=#9900FF>Note.</font> from details of addresses Andrew Pennell gave in the magazine "Your
+;   Sinclair" it can be deduced that the unpublished ROM 3 had two extra
+;   instruction bytes at this point and together with a cleanup, this may have
+;   addressed the above issue.
+;   Now prepare to overwrite the unusable sectors (which are mapped as usable)
+;   with record descriptors which are usable.
+        CALL    <A href="#L1E49">L1E49</a>           ; routine IN-CHK marks the channel record
+                                ; descriptor fields as usable by blanking
+                                ; both RECFLG and RECLEN and then inserting
+                                ; the descriptor checksum.
+;   A loop is now entered to write usable datablocks to every sector indicated
+;   as usable in the microdrive map.
+<a name="L1C40"></a>;; <b>MARK-FREE</b>
+L1C40:  CALL    <A href="#L1349">L1349</a>           ; routine CHK-FULL checks if there is still a
+                                ; usable sector on the cartridge.
+        JR      NZ,<A href="#L1C4D">L1C4D</a>        ; forward, if so, to MK-BLK.
+;   The FORMAT operation is now complete.
+        XOR     A               ; select no motor
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE stops the microdrive motor.
+        CALL    <A href="#L119F">L119F</a>           ; routine DEL-M-BUF deletes the microdrive
+                                ; buffer and the microdrive map.
+        RET                     ; return.                          &gt;&gt;&gt;&gt;&gt;&gt;&gt;
+; ---
+<a name="L1C4D"></a>;; <b>MK-BLK</b>
+L1C4D:  CALL    <A href="#L135A">L135A</a>           ; routine SEND-BLK writes block to microdrive
+                                ; cartridge as indicated by the microdrive map
+                                ; which is then updated by the routine.
+        JR      <A href="#L1C40">L1C40</a>           ; loop back to MARK-FREE
+; -------------------------
+; THE <b><font color=#333388>'CAT COMMAND'</font></b> ROUTINE
+; -------------------------
+;
+<a name="L1C52"></a>;; <b>CAT</b>
+L1C52:  LD      A,($5CD8)       ; fetch output stream from S_STR1
+        RST     10H             ; CALBAS
+        DEFW    $1601           ; main CHAN-OPEN
+        CALL    <A href="#L10A5">L10A5</a>           ; routine SET-T-MCH sets a temporary channel.
+        LD      A,(IX+$19)      ; fetch drive number from CHDRIV.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE starts the motor.
+        LD      BC,$0032        ; set maximum sector to 50 and initialize
+                                ; value of sectors read to zero.
+        LD      ($5CC9),BC      ; update system variable SECTOR
+;   On the original Interface 1 ROM operations like CAT and ERASE were quite
+;   slow as the routines assumed the theoretical maximum number of sectors was
+;   256.  In reality, the maximum number of sectors on a microdrive is
+;   approximately 180, so the original routines spent the last 3 seconds
+;   reading about 75 sectors for the second time.  The improved algorithm above
+;   is to keep a record of the maximum sector + 3 and when the number of
+;   visited sectors is equal to this number then a complete revolution of the
+;   tape has been made and the operation can cease. The overhead of three is
+;   to ensure that bad sectors or the tape splice do not cause the operation to
+;   end prematurely.
+;   Happily, this algorithm also works with emulators which usually provide the
+;   full 256 sectors.
+<a name="L1C68"></a>;; <b>CAT-LP</b>
+L1C68:  CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads in 14 byte header.
+        LD      A,(IX+$29)      ; fetch value of sector from HDNUMB
+        ADD     A,$03           ; add 3 to value.
+        LD      HL,$5CC9        ; address system variable SECTOR_lo
+        CP      (HL)            ; compare to contents
+        JR      C,<A href="#L1C77">L1C77</a>         ; forward if A is less to CAT-LP-E
+        LD      (HL),A          ; else update SECTOR_lo with higher value.
+<a name="L1C77"></a>;; <b>CAT-LP-E</b>
+L1C77:  CALL    <A href="#L1E5E">L1E5E</a>           ; routine G-RDES loads only a
+                                ; 14 byte record descriptor.
+        JR      NZ,<A href="#L1C68">L1C68</a>        ; back, with error or mismatch, to CAT-LP
+; a record can be considered in use if either the RECLEN is maximum $0200 or
+; the RECFLG indicates that it is the seldom full EOF record.
+        LD      A,(IX+$43)      ; RECFLG
+        OR      (IX+$46)        ; RECLEN_hi
+        AND     $02             ;
+        JR      NZ,<A href="#L1C8B">L1C8B</a>        ; forward, if used, to IN-NAME
+; else mark sector free in microdrive map and find next sector.
+        CALL    <A href="#L13E3">L13E3</a>           ; routine RES-B-MAP
+        JR      <A href="#L1CF4">L1CF4</a>           ; forward to F-N-SCT
+; a name is to be inserted in the 512 byte data buffer workspace, if it is not
+; there already. Secret files are not listed.
+<a name="L1C8B"></a>;; <b>IN-NAME</b>
+L1C8B:  LD      A,(IX+$47)      ; take first character of RECNAM
+        OR      A               ; test for zero.
+        JR      Z,<A href="#L1CF4">L1CF4</a>         ; forward, if CHR$ 0, to F-N-SCT
+        PUSH    IX              ; transfer base address
+        POP     HL              ; to HL register.
+        LD      DE,$0052        ; offset to start of data buffer.
+        ADD     HL,DE           ; add to address names.
+        LD      DE,$000A        ; set DE to ten, the length of a name.
+        LD      B,$00           ; set high byte to zero.
+        LD      C,(IX+$0D)      ; fetch name total from CHREC initially zero.
+<a name="L1CA0"></a>;; <b>SE-NAME</b>
+L1CA0:  LD      A,C             ; test name count for zero
+        OR      A               ;
+        JR      Z,<A href="#L1CDA">L1CDA</a>         ; forward, with first name, to INS-NAME
+        PUSH    HL              ; save buffer address.
+        PUSH    IX              ; save channel base address.
+        PUSH    BC              ; save name total.
+        LD      B,$0A           ; set character counter to ten.
+<a name="L1CAA"></a>;; <b>T-NA-1</b>
+L1CAA:  LD      A,(HL)          ; take letter of buffered name.
+        CP      (IX+$47)        ; compare to that in RECNAM
+        JR      NZ,<A href="#L1CB5">L1CB5</a>        ; forward, with mismatch, to T-NA-2
+        INC     HL              ; increment
+        INC     IX              ; both pointers.
+        DJNZ    <A href="#L1CAA">L1CAA</a>           ; back, for all ten, to T-NA-1
+<a name="L1CB5"></a>;; <b>T-NA-2</b>
+L1CB5:  POP     BC              ; restore
+        POP     IX              ; all
+        POP     HL              ; pointers.
+; if all ten characters match then find next sector.
+        JR      Z,<A href="#L1CF4">L1CF4</a>         ; forward to F-N-SCT
+; if buffered name is higher than new name then re-order to create a slot.
+        JR      NC,<A href="#L1CC1">L1CC1</a>        ; forward to ORD-NAM
+; else add ten to buffer address and compare with following name performing
+; a simple insert if the end of the list is reached.
+        ADD     HL,DE           ; add ten to address.
+        DEC     C               ; decrement name counter.
+        JR      <A href="#L1CA0">L1CA0</a>           ; back to SE-NAME
+; ---
+<a name="L1CC1"></a>;; <b>ORD-NAM</b>
+L1CC1:  PUSH    HL              ; save pointer to start of name slot.
+        PUSH    DE              ; save the value ten.
+        PUSH    BC              ; save the buffered name counter.
+        PUSH    HL              ; save address of name slot again.
+        SLA     C               ; double name count.
+        LD      H,B             ; set H to zero.
+        LD      L,C             ; HL = 2 * count
+        ADD     HL,BC           ; HL = 4 * count
+        ADD     HL,BC           ; HL = 6 * count        <font color=#9900FF>Note.</font> add hl,hl doubles.
+        ADD     HL,BC           ; HL = 8 * count        c.f. Main ROM
+        ADD     HL,BC           ; HL = 10 * count
+        LD      B,H             ; transfer number of bytes
+        LD      C,L             ; to be moved to BC register.
+        POP     HL              ; restore address of insertion point.
+        DEC     HL              ; decrement and then add
+        ADD     HL,BC           ; bytes to be moved to point to end of block.
+        EX      DE,HL           ; now make DE
+        ADD     HL,DE           ; the destination
+        EX      DE,HL           ; ten bytes higher.
+        LDDR                    ; slide the block of higher names upwards.
+        POP     BC              ; restore name count.
+        POP     DE              ; restore ten value.
+        POP     HL              ; restore insertion point.
+<a name="L1CDA"></a>;; <b>INS-NAME</b>
+L1CDA:  PUSH    IX              ; save channel base address.
+        LD      B,$0A           ; set character count to ten.
+<a name="L1CDE"></a>;; <b>MOVE-NA</b>
+L1CDE:  LD      A,(IX+$47)      ; fetch a character from new name at RECNAM
+        LD      (HL),A          ; insert into buffer.
+        INC     IX              ; increment both
+        INC     HL              ; pointers.
+        DJNZ    <A href="#L1CDE">L1CDE</a>           ; loop back to MOVE-NA
+        POP     IX              ; restore channel base address.
+        LD      A,(IX+$0D)      ; fetch count of names from CHREC
+        INC     A               ; increment
+        LD      (IX+$0D),A      ; and store back in CHREC
+        CP      $32             ; compare to maximum of 50.
+        JR      Z,<A href="#L1CFF">L1CFF</a>         ; forward, if buffer filled, to BF-FILLED
+<a name="L1CF4"></a>;; <b>F-N-SCT</b>
+L1CF4:  LD      HL,$5CCA        ; sv SECTOR_hi
+        LD      A,(HL)          ; fetch actual count of used sectors.
+        INC     A               ; and increment.
+        LD      (HL),A          ; update SECTOR_hi
+        DEC     HL              ; address system variable SECTOR_lo
+        CP      (HL)            ; compare
+        JP      C,<A href="#L1C68">L1C68</a>         ; jump to CAT-LP
+<a name="L1CFF"></a>;; <b>BF-FILLED</b>
+L1CFF:  PUSH    IX              ;
+        XOR     A               ; clear accumulator
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE stops the motor.
+        PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$002C        ; offset to cartridge name HDNAME.
+        ADD     HL,DE           ; add the offset to address the name.
+        CALL    <A href="#L1D5B">L1D5B</a>           ; routine PRNAME prints name and a carriage
+                                ; return.
+        LD      A,$0D           ; prepare an extra carriage return.
+        CALL    <A href="#L1D71">L1D71</a>           ; routine PRCHAR outputs it.
+        PUSH    IX              ;
+        POP     HL              ;
+        LD      DE,$0052        ; offset to CHDATA - the 512 byte data buffer.
+        ADD     HL,DE           ; add to address list of up to fifty names.
+        LD      B,(IX+$0D)      ; load B with count of names from CHREC
+        LD      A,B             ; test for
+        OR      A               ; zero.
+        JR      Z,<A href="#L1D27">L1D27</a>         ; forward, if so, to NONAMES
+<a name="L1D22"></a>;; <b>OT-NAMS</b>
+L1D22:  CALL    <A href="#L1D5B">L1D5B</a>           ; routine PRNAME
+        DJNZ    <A href="#L1D22">L1D22</a>           ; loop back to OT-NAMS
+<a name="L1D27"></a>;; <b>NONAMES</b>
+L1D27:  CALL    <A href="#L1D43">L1D43</a>           ; routine FREESECT
+        LD      A,E             ;
+        SRL     A               ;
+        RST     10H             ; CALBAS
+        DEFW    $2D28           ; main STACK-A
+        LD      A,$0D           ;
+        CALL    <A href="#L1D71">L1D71</a>           ; routine PRCHAR
+        RST     10H             ; CALBAS
+        DEFW    $2DE3           ; main PRINT-FP
+        LD      A,$0D           ;
+        CALL    <A href="#L1D71">L1D71</a>           ; routine PRCHAR
+        POP     IX              ;
+        CALL    <A href="#L119F">L119F</a>           ; routine DEL-M-BUF
+        RET                     ; return.
+; ----------------------
+; THE <b><font color=#333388>'FREESECT'</font></b> ROUTINE
+; ----------------------
+;   This routine is called from SAVE and CAT to calculate the number of free
+;   sectors that are present on a microdrive from the map information.
+;   The count of free sectors is returned in the E register.
+<a name="L1D43"></a>;; <b>FREESECT</b>
+L1D43:  LD      L,(IX+$1A)      ; address of microdrive map.
+        LD      H,(IX+$1B)      ; for channel transferred to HL.
+        LD      E,$00           ; initialize sector count to zero.
+        LD      C,$20           ; there are thirty two bytes to examine.
+<a name="L1D4D"></a>;; <b>FR-SC-LP</b>
+L1D4D:  LD      A,(HL)          ; fetch a byte from the map.
+        INC     HL              ; address next map location.
+        LD      B,$08           ; count eight bits.
+<a name="L1D51"></a>;; <b>FR-S-LPB</b>
+L1D51:  RRA                     ; rotate right.
+        JR      C,<A href="#L1D55">L1D55</a>         ; forward, with carry, to FR-S-RES.
+        INC     E               ; increment the free sector count.
+<a name="L1D55"></a>;; <b>FR-S-RES</b>
+L1D55:  DJNZ    <A href="#L1D51">L1D51</a>           ; loop back for all eight bits to FR-S-LPB.
+        DEC     C               ; decrement byte count.
+        JR      NZ,<A href="#L1D4D">L1D4D</a>        ; loop back for thirty two bytes to FR-SC-LP.
+        RET                     ; return.
+; --------------------
+; THE <b><font color=#333388>'PRNAME'</font></b> ROUTINE
+; --------------------
+;   This routine outputs a ten character name, followed by a carriage return,
+;   and is used by the CAT command to first print the cartridge name and then
+;   the filenames on the cartridge.
+;   <font color=#9900FF>Note.</font> For a routine that can output to any stream, it seems straightforward
+;   until one notices the call to TEMPS at the end.  This applies the permanent
+;   colour screen attributes to the temporary set and has been placed within
+;   the routine as a security measure to ensure that if the cartridge name
+;   or filename contains a string of colour control codes that render filenames
+;   invisible then their effect does not last beyond the current name.
+;
+;   On the other hand, colour control codes can be used in the cartridge name
+;   without affecting the cartridge contents display.
+<a name="L1D5B"></a>;; <b>PRNAME</b>
+L1D5B:  PUSH    BC              ; preserve name count.
+        LD      B,$0A           ; ten characters per name.
+<a name="L1D5E"></a>;; <b>PRNM-LP</b>
+L1D5E:  LD      A,(HL)          ; fetch a character.
+        CALL    <A href="#L1D71">L1D71</a>           ; routine PRCHAR
+        INC     HL              ; point to next character.
+        DJNZ    <A href="#L1D5E">L1D5E</a>           ; loop back for all ten to PRNM-LP
+        LD      A,$0D           ; prepare a carriage return.
+        CALL    <A href="#L1D71">L1D71</a>           ; routine PRCHAR
+        PUSH    HL              ; preserve character address.
+        RST     10H             ; CALBAS
+        DEFW    $0D4D           ; main TEMPS restores temporary colours from
+                                ; the permanent colours after each name.
+        POP     HL              ; restore character address.
+        POP     BC              ; restore name count.
+        RET                     ; return.
+; --------------------
+; THE <b><font color=#333388>'PRCHAR'</font></b> ROUTINE
+; --------------------
+;   The PRINT CHARACTER routine utilizes the output restart in the main ROM
+;   which outputs to any stream and so a stream such as the "T" channel
+;   could be sent output. The IX register has therefore to be preserved.
+<a name="L1D71"></a>;; <b>PRCHAR</b>
+L1D71:  PUSH    IX              ; preserve this ad hoc channel address.
+        RST     10H             ; CALBAS
+        DEFW    $0010           ; main PRINT-A
+        POP     IX              ; restore this channel address.
+        RET                     ; return.
+; ---------------------------
+; THE <b><font color=#333388>'ERASE COMMAND'</font></b> ROUTINE
+; ---------------------------
+; <font color=#339933>(Hook Code: $24)</font>
+;   The ERASE command is in two stages and uses the first 32 bytes of the
+;   otherwise unused data buffer to map out the sectors to be marked clear.
+;   The first stage performs this mapping and in one revolution of the tape
+;   it should find all sectors that have the specified name.  It should also
+;   find the EOF record, which all files have, and which contains in the
+;   RECNUM field the maximum record number. For example with four records the
+;   numbers will be 0, 1, 2, 3.
+;   Once the number of marked records equals the max record plus one then the
+;   second stage can begin which is to mark free all the records.
+;
+;   There are two circumstances under which the procedure might not be so
+;   straightforward.
+;   The first is if the user has pressed BREAK during a previous ERASE
+;   operation after a few records were marked free.
+;   The second is if the file has been saved with the System Variable COPIES
+;   holding a value larger than 1. For example with a value of 5, there will
+;   be five EOF records and five records with RECNUM equal to zero etc.
+;
+;   For the first case the command will make five revolutions of the tape
+;   before marking all found sectors free.
+;   This may happen in the second case also if more multi records were found
+;   before the first EOF record was encountered.
+;   It is more likely that the ERASE command will have to be invoked several
+;   times to erase the file.  It is simpler to issue the command within a
+;   loop.  Multiple copy files are usually saved as part of a well-considered
+;   scheme and are seldom subsequently erased.
+<a name="L1D79"></a>;; <b>ERASE</b>
+L1D79:  CALL    <A href="#L10A5">L10A5</a>           ; routine SET-T-MCH creates a temporary channel
+                                ; using either an existing microdrive map from
+                                ; a channel also using this drive or allocating
+                                ; a new one initialized to $FF bytes.
+        LD      A,(IX+$19)      ; fetch drive number from CHDRIV.
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE starts motor.
+        IN      A,($EF)         ; read microdrive port.
+        AND     $01             ; isolate 'write prot.' bit.
+        JR      NZ,<A href="#L1D8A">L1D8A</a>        ; forward, if not zero, to ERASE-1
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0E             ; Drive 'write' protected
+<a name="L1D8A"></a>;; <b>ERASE-1</b>
+L1D8A:  PUSH    IX              ; transfer address of start of channel.
+        POP     HL              ; to the HL register.
+        LD      DE,$0052        ; prepare offset to data buffer.
+        ADD     HL,DE           ; add to address start.
+;   A pseudo microdrive map will also be created within the buffer conserving
+;   memory.  This is initialized to $00 bytes.
+        PUSH    HL              ; transfer buffer address
+        POP     DE              ; from HL to DE register
+        INC     DE              ; and increment address.
+        LD      BC,$001F        ; set counter to 31 and B to zero.
+        XOR     A               ; set A to zero.
+        LD      (HL),A          ; insert zero in first location.
+        LDIR                    ; copy to other 31 addresses
+        LD      A,$FF           ; prepare, as a default, to examine every sector.
+        LD      (IX+$0D),A      ; update CHREC with max record number.
+        LD      BC,$04FB        ; prepare decimal 1275 (5+ revolutions)
+        LD      ($5CC9),BC      ; update system variable SECTOR
+;   <font color=#9900FF>Note.</font> if the EOF record is not found, or if the number of found sectors
+;   doesn't equal the maximum record then 5+ revolutions of the tape will
+;   occur after which all mapped sectors will be erased. Normally with a
+;   simple file it's all over in less than two revolutions.
+<a name="L1DA7"></a>;; <b>ERASE-LP</b>
+L1DA7:  CALL    <A href="#L13F7">L13F7</a>           ; routine DEC-SECT decrements the 1275 counter.
+        JR      Z,<A href="#L1E03">L1E03</a>         ; forward, if zero, to ERASE-MK
+        CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads the next 14-byte
+                                ; header to pass the tape heads.
+        CALL    <A href="#L1E5E">L1E5E</a>           ; routine G-RDES reads the corresponding
+                                ; 14-byte record descriptor for this sector.
+        JR      NZ,<A href="#L1DE5">L1DE5</a>        ; forward, with read error, to TST-NUM
+;   now check if sector is in use.  Considered it so if next position is
+;   at $0200 or if it is the EOF record.
+        LD      A,(IX+$43)      ; RECFLG
+        OR      (IX+$46)        ; RECLEN_hi
+        AND     $02
+        JR      NZ,<A href="#L1DC3">L1DC3</a>        ; forward, if in use, to ERASE-2
+                                ; to consider for erasure.
+; the sector is not used so reset the REAL microdrive map bit.
+        CALL    <A href="#L13E3">L13E3</a>           ; routine RES-B-MAP resets sector bit on
+                                ; the REAL microdrive map.
+        JR      <A href="#L1DE5">L1DE5</a>           ; forward to TST-NUM
+; ---
+;   consider for erasure if filename matches.
+<a name="L1DC3"></a>;; <b>ERASE-2</b>
+L1DC3:  PUSH    IX              ; transfer channel base address
+        POP     HL              ; to the HL register.
+        LD      DE,$0047        ; offset to 10 characters of filename.
+        ADD     HL,DE           ; add so HL addresses the start of RECNAM.
+        LD      BC,$000A        ; ten bytes to compare against required CHNAME.
+        CALL    <A href="#L1403">L1403</a>           ; routine CHK-NAME
+        JR      NZ,<A href="#L1DE5">L1DE5</a>        ; forward, with no match, to TST-NUM
+; the name matches so sector is marked free.
+        CALL    <A href="#L13EB">L13EB</a>           ; routine TEST-PMAP obtains address of sector
+                                ; bit in HL and bit mask in B.
+        LD      A,B             ; transfer mask to B
+        OR      (HL)            ; combine with addressed byte
+        LD      (HL),A          ; and update setting the sector bit.
+        BIT     1,(IX+$43)      ; test RECFLG is this an EOF record.
+        JR      Z,<A href="#L1DE5">L1DE5</a>         ; forward, if not, to TST-NUM
+; All files should have an EOF record and, if this is it, then the endpoint
+; can be reduced from $FF to record number plus one as range starts at 1.
+        LD      A,(IX+$44)      ; fetch record number from RECNUM
+        INC     A               ; increment as CHREC value starts at one not
+                                ; zero.
+        LD      (IX+$0D),A      ; update the endpoint CHREC
+<a name="L1DE5"></a>;; <b>TST-NUM</b>
+L1DE5:  PUSH    IX              ; transfer the channel base address
+        POP     HL              ; to the HL register.
+        LD      DE,$0052        ; add offset to data
+        ADD     HL,DE           ; to address the pseudomap.
+        LD      E,$00           ; initialize E to zero.
+        LD      C,$20           ; and C counter to thirty two.
+<a name="L1DF0"></a>;; <b>LP-P-MAP</b>
+L1DF0:  LD      A,(HL)          ; fetch a byte from pseudomap
+        INC     HL              ; and increment the address.
+        LD      B,$08           ; set bit counter to eight.
+<a name="L1DF4"></a>;; <b>LP-B-MAP</b>
+L1DF4:  RRA                     ; rotate end bit to carry.
+        JR      NC,<A href="#L1DF8">L1DF8</a>        ; forward, with no carry, to NOINC-C
+        INC     E               ; increment recno
+<a name="L1DF8"></a>;; <b>NOINC-C</b>
+L1DF8:  DJNZ    <A href="#L1DF4">L1DF4</a>           ; back to LP-B-MAP for all eight bits.
+        DEC     C               ; decrement byte counter.
+        JR      NZ,<A href="#L1DF0">L1DF0</a>        ; back to LP-P-MAP for all 32 bytes.
+; now E holds the number of records marked for erasure in range 1 to NR.
+        LD      A,(IX+$0D)      ; fetch records to be erased from CHREC
+        CP      E               ; compare to records marked for erasure.
+        JR      NZ,<A href="#L1DA7">L1DA7</a>        ; back, if not exact match, to ERASE-LP
+;   Now the second stage begins. Since the pseudomap has a representation of
+;   all the records to be erased we can load the headers one by one, and
+;   rewrite the corresponding records with a clear one in the channel.
+;   The same record is written after all the appropriate headers. Fields
+;   like RECNUM only have relevance when the record is in use.
+;
+;   First prepare a clear record descriptor.  The actual data buffer does not
+;   have to be clear and in fact contains the pseudomap. Note also that the
+;   checksum for the data need not be calculated but the checksum for the
+;   record descriptor is required to be accurate.
+<a name="L1E03"></a>;; <b>ERASE-MK</b>
+L1E03:  CALL    <A href="#L1E49">L1E49</a>           ; routine IN-CHK marks the channel record
+                                ; descriptor fields as usable by blanking
+                                ; both RECFLG and RECLEN and then inserting
+                                ; the descriptor checksum.
+; now enter a loop for all marked records.
+<a name="L1E06"></a>;; <b>ERASE-MK2</b>
+L1E06:  CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads the next header
+                                ; to pass the tape heads.
+        CALL    <A href="#L13EB">L13EB</a>           ; routine TEST-PMAP checks if the sector,
+                                ; (in HDNUMB) is marked to be erased in the
+                                ; pseudomap.
+        JR      Z,<A href="#L1E31">L1E31</a>         ; forward, if not, to T-OTHER
+; this record is marked for erasure.
+        PUSH    HL              ; save pseudomap sector bit address.
+        PUSH    BC              ; save pseudomap bit mask which has one set bit.
+        LD      A,$E6           ; enable writing.
+        OUT     ($EF),A         ; output to microdrive port.
+        LD      BC,$0168        ; set counter to 360 decimal.
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC pauses briefly as the
+                                ; record now approaches the tape heads.
+        PUSH    IX              ; transfer channel base address
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0037        ; offset to record PREAMBLE.
+        ADD     HL,DE           ; add to form start of save address.
+        CALL    <A href="#L15B3">L15B3</a>           ; routine OUT-M-BUF rewrites descriptor and
+                                ; data buffer. The descriptor is checksummed,
+                                ; the data is not.
+        LD      A,$EE           ; disable writing
+        OUT     ($EF),A         ; output to microdrive port
+; now update bit the real microdrive map and the pseudomap.
+        CALL    <A href="#L13E3">L13E3</a>           ; routine RES-B-MAP resets appropriate bit
+                                ; for the now free sector in the REAL
+                                ; microdrive map.
+        POP     BC              ; restore the pseudomap bit mask.
+        POP     HL              ; restore the pseudomap sector bit address.
+        LD      A,B             ; transfer bitmask to B.
+        CPL                     ; the set bit is now reset and the other seven
+                                ; bits are set.
+        AND     (HL)            ; reset the bit in the pseudomap
+        LD      (HL),A          ; and update.
+; now check if there are any more sectors to do.
+<a name="L1E31"></a>;; <b>T-OTHER</b>
+L1E31:  PUSH    IX              ; transfer channel base address
+        POP     HL              ; to the HL register.
+        LD      DE,$0052        ; prepare offset to the pseudomap
+        ADD     HL,DE           ; and add to address start of map.
+        LD      B,$20           ; set byte count to thirty two.
+<a name="L1E3A"></a>;; <b>CHK-W-MAP</b>
+L1E3A:  LD      A,(HL)          ; fetch a byte representing eight sectors.
+        OR      A               ; test for zero.
+        JR      NZ,<A href="#L1E06">L1E06</a>        ; back, if a byte is not zero, to ERASE-MK2
+        INC     HL              ; increment the map address
+        DJNZ    <A href="#L1E3A">L1E3A</a>           ; loop back to CHK-W-MAP for all 32 bytes.
+; at this point all records have been erased and it only remains to clear up.
+        XOR     A               ; select no motor
+        CALL    <A href="#L1532">L1532</a>           ; routine SEL-DRIVE stops the motor.
+        CALL    <A href="#L119F">L119F</a>           ; routine DEL-M-BUF deletes the adhoc buffer.
+        RET                     ; return.
+; -----------------------------------
+; THE <b><font color=#333388>'PREPARE '</font></b>FREE SECTOR'' ROUTINE
+; -----------------------------------
+;   The two indicators within the current channel are marked clear and the
+;   RECORD DESCRIPTOR is checksumed in preparation for writing to each sector
+;   to be marked free.
+<a name="L1E49"></a>;; <b>IN-CHK</b>
+L1E49:  XOR     A               ; clear accumulator A.
+        LD      (IX+$43),A      ; blank RECFLG.
+        LD      (IX+$45),A      ; blank RECLEN_lo.
+        LD      (IX+$46),A      ; blank RECLEN_hi.
+        PUSH    IX              ; transfer the start of channel
+        POP     HL              ; to the HL register pair.
+        LD      DE,$0043        ; prepare the offset to RECFLG.
+        ADD     HL,DE           ; add to form start of record descriptor.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R inserts 14-byte checksum.
+        RET                     ; return.
+; --------------------------------------
+; THE <b><font color=#333388>'OBTAIN RECORD DESCRIPTOR'</font></b> ROUTINE
+; --------------------------------------
+; This routine is used by CAT, ERASE and the GET-DESC Hook Code $33.
+; It loads and verifies the 14 byte record descriptor from RECFLG to RECNAM.
+; This is normally loaded with the following data block
+; or with the header block.
+; The Zero Flag is set upon successful completion.
+<a name="L1E5E"></a>;; <b>G-RDES</b>
+L1E5E:  PUSH    IX              ; transfer channel address
+        POP     HL              ; to HL register.
+        LD      DE,$0043        ; offset to RECFLG
+        ADD     HL,DE           ; add to form first receiving location.
+        CALL    <A href="#L15E2">L15E2</a>           ; routine GET-M-HD reads in 15 bytes.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R checksums the first 14 bytes
+        RET     NZ              ; return with checksum error.
+        BIT     0,(IX+$43)      ; test bit 0 of RECFLAG - should be zero
+        RET                     ; return.
+; -----------------------
+; THE <b><font color=#333388>'HOOK-CODE'</font></b> ROUTINE
+; -----------------------
+; This accesses the twenty six hook codes now reduced to the range $00 - $19.
+<a name="L1E71"></a>;; <b>HOOK-CODE</b>
+L1E71:  CP      $1A             ; compare to upper limit.
+        JR      C,<A href="#L1E77">L1E77</a>         ; forward, if valid, to CLR-ERR.
+        RST     20H             ; Shadow Error Restart.
+        DEFB    $12             ; Hook code error.
+; ---
+<a name="L1E77"></a>;; <b>CLR-ERR</b>
+L1E77:  LD      (IY+$00),$FF    ; set ERR_NR to one less than zero - no error.
+        SET     2,(IY+$01)      ; update FLAGS signal 'L' mode.
+        INC     HL              ; step past the hook code location in RAM.
+        EX      (SP),HL         ; make this the return address.
+        PUSH    HL              ; push back what was at stack pointer - the
+                                ; preserved value of AF on entry.
+        ADD     A,A             ; double the code.
+        LD      D,$00           ; set D to zero for indexing.
+        LD      E,A             ; transfer the code to E.
+        LD      HL,<A href="#L1E99">L1E99</a>        ; address: HOOK-TAB the base of the Hook Codes.
+        ADD     HL,DE           ; index into this table.
+        LD      E,(HL)          ; low byte to E.
+        INC     HL              ; increment pointer.
+        LD      D,(HL)          ; high byte to D.
+        POP     AF              ; restore AF from machine stack.
+        LD      HL,<A href="#L0700">L0700</a>        ; push the address UNPAGE
+        PUSH    HL              ; on the machine stack.
+        EX      DE,HL           ; transfer address to HL.
+        JP      (HL)            ; jump to Hook Code routine.
+; ---------------------------
+; THE <b><font color=#333388>'HOOK CODE +32'</font></b> ROUTINE
+; ---------------------------
+; <font color=#339933>(Hook Code: $32)</font>
+;   This allows the user to call any address in the shadow ROM.
+<a name="L1E94"></a>;; <b>HOOK-32</b>
+L1E94:  LD      HL,($5CED)      ; sv HD_11
+        JP      (HL)            ; jump to routine.
+; ---------------------------
+; THE <b><font color=#333388>'HOOK CODE +31'</font></b> ROUTINE
+; ---------------------------
+; <font color=#339933>(Hook Code: $31)</font>
+; This Hook Code ensures that the extra System Variables are created. Since
+; this has already occurred, as is the case with all Hook Codes, then all that
+; remains to do is to return to the address on the stack - the UNPAGE location.
+<a name="L1E98"></a>;; <b>HOOK-31</b>
+L1E98:  RET                     ; return.
+; -------------------------------
+; THE <b><font color=#333388>'HOOK CODE ADDRESSES'</font></b> TABLE
+; -------------------------------
+;   The addresses of the Hook Codes.  The last two are new to this ROM.
+<a name="L1E99"></a>;; <b>HOOK-TAB</b>
+L1E99:  DEFW    <A href="#L1ECD">L1ECD</a>           ; $1B - CONS-IN
+        DEFW    <A href="#L1EE0">L1EE0</a>           ; $1C - CONS-OUT
+        DEFW    <A href="#L0B88">L0B88</a>           ; $1D - BCHAN-IN
+        DEFW    <A href="#L0D07">L0D07</a>           ; $1E - BCHAN-OUT
+        DEFW    <A href="#L1EF0">L1EF0</a>           ; $1F - PRT-OUT
+        DEFW    <A href="#L1EF5">L1EF5</a>           ; $20 - KBD-TEST
+        DEFW    <A href="#L1532">L1532</a>           ; $21 - SEL-DRIVE
+        DEFW    <A href="#L1B05">L1B05</a>           ; $22 - OP-TEMP-M
+        DEFW    <A href="#L138E">L138E</a>           ; $23 - CLOSE-M2
+        DEFW    <A href="#L1D79">L1D79</a>           ; $24 - ERASE
+        DEFW    <A href="#L1EFD">L1EFD</a>           ; $25 - READ-SEQ
+        DEFW    <A href="#L12DA">L12DA</a>           ; $26 - WR-RECD
+        DEFW    <A href="#L1F0B">L1F0B</a>           ; $27 - RD-RANDOM
+        DEFW    <A href="#L1F3F">L1F3F</a>           ; $28 - RD-SECTOR
+        DEFW    <A href="#L1F7A">L1F7A</a>           ; $29 - RD-NEXT
+        DEFW    <A href="#L1F85">L1F85</a>           ; $2A - WR-SECTOR
+        DEFW    <A href="#L10A5">L10A5</a>           ; $2B - SET-T-MCH
+        DEFW    <A href="#L119F">L119F</a>           ; $2C - DEL-M-BUF
+        DEFW    <A href="#L0F46">L0F46</a>           ; $2D - OP-TEMP-N
+        DEFW    <A href="#L1F18">L1F18</a>           ; $2E - CLOSE-NET
+        DEFW    <A href="#L1F25">L1F25</a>           ; $2F - GET-PACK
+        DEFW    <A href="#L0E4F">L0E4F</a>           ; $30 - SEND-PACK
+        DEFW    <A href="#L1E98">L1E98</a>           ; $31 - HOOK-31
+        DEFW    <A href="#L1E94">L1E94</a>           ; $32 - HOOK-32
+        DEFW    <A href="#L1FE4">L1FE4</a>           ; $33 - GET-DESC
+        DEFW    <A href="#L1FF6">L1FF6</a>           ; $34 - OP-B-CHAN
+; ---------------------------
+; THE <b><font color=#333388>'CONSOLE INPUT'</font></b> ROUTINE
+; ---------------------------
+; <font color=#339933>(Hook Code: $1B)</font>
+<a name="L1ECD"></a>;; <b>CONS-IN</b>
+L1ECD:  EI                      ; enable interrupts.
+        RES     5,(IY+$01)      ; update FLAGS signal no new key pressed.
+<a name="L1ED2"></a>;; <b>WTKEY</b>
+L1ED2:  HALT                    ; wait for an interrupt.
+        RST     10H             ; CALBAS
+        DEFW    $02BF           ; main KEYBOARD
+        BIT     5,(IY+$01)      ; test FLAGS - new key ?
+        JR      Z,<A href="#L1ED2">L1ED2</a>         ; loop back, if not, to WTKEY
+        LD      A,($5C08)       ; place decoded key in system variable LASTK
+        RET                     ; return.
+; ----------------------------
+; THE <b><font color=#333388>'CONSOLE OUTPUT'</font></b> ROUTINE
+; ----------------------------
+; <font color=#339933>(Hook Code: $1C)</font>
+;   outputs a character to the unalterable system stream for the console.
+<a name="L1EE0"></a>;; <b>CONS-OUT</b>
+L1EE0:  PUSH    AF              ; save character to be output.
+        LD      A,$FE           ; use system stream $FE - upper screen.
+; -&gt;
+<a name="L1EE3"></a>;; <b>OUT-CODE</b>
+L1EE3:  LD      HL,$5C8C        ; address system variable SCR_CT.
+        LD      (HL),$FF        ; load with a high number to suppress scroll
+                                ; prompt.
+        RST     10H             ; CALBAS
+        DEFW    $1601           ; main CHAN-OPEN opens selected stream.
+        POP     AF              ; fetch the preserved print character.
+        RST     10H             ; CALBAS
+        DEFW    $0010           ; main PRINT-A prints character in accumulator.
+        RET                     ; return.
+; ----------------------------
+; THE <b><font color=#333388>'PRINTER OUTPUT'</font></b> ROUTINE
+; ----------------------------
+; <font color=#339933>(Hook code: $1D)</font>
+;   outputs a character to stream 3.
+<a name="L1EF0"></a>;; <b>PRT-OUT</b>
+L1EF0:  PUSH    AF              ; preserve character to be printed
+        LD      A,$03           ; select stream 3
+        JR      <A href="#L1EE3">L1EE3</a>           ; back to OUT-CODE
+; ---------------------------
+; THE <b><font color=#333388>'KEYBOARD TEST'</font></b> ROUTINE
+; ---------------------------
+; ( Hook Code: $20 )
+; Normally a single reset bit in A determines which half row is read but by
+; resetting all bits the entire keyboard is read.  A pressed key will cause
+; a bit to be reset.  Routine returns with zero flag set if no keys pressed,
+; NZ otherwise.
+<a name="L1EF5"></a>;; <b>KBD-TEST</b>
+L1EF5:  XOR     A               ; reset all eight high-order bits.
+        IN      A,($FE)         ; read the entire keyboard.
+        AND     $1F             ; retain any unpressed keys - will be $1F if
+                                ; no key.
+        SUB     $1F             ; subtract to give zero if no keys.
+        RET                     ; return.
+; -------------------------------
+; THE <b><font color=#333388>'READ SEQUENTIAL'</font></b> HOOK CODE
+; -------------------------------
+; <font color=#339933>(Hook Code: $25)</font>
+;
+<a name="L1EFD"></a>;; <b>READ-SEQ</b>
+L1EFD:  BIT     1,(IX+$43)      ; RECFLG
+        JR      Z,<A href="#L1F08">L1F08</a>         ; forward to INCREC
+        LD      (IY+$00),$07    ; set ERR_NR to '8 End of file'
+        RST     28H             ; Error Main ROM
+; ---
+<a name="L1F08"></a>;; <b>INCREC</b>
+L1F08:  INC     (IX+$0D)        ; increment the required record in CHREC
+                                ; and continue into next routine...
+; ---------------------------
+; THE <b><font color=#333388>'READ RANDOM'</font></b> HOOK CODE
+; ---------------------------
+; <font color=#339933>(Hook Code: $27)</font>
+;   reads a PRINT record randomly.
+<a name="L1F0B"></a>;; <b>RD-RANDOM</b>
+L1F0B:  CALL    <A href="#L1252">L1252</a>           ; routine GET-RECD gets the record specified
+                                ; by CHREQ matching filename CHNAME from the
+                                ; cartridge in the drive CHDRIV which is
+                                ; started.
+        BIT     2,(IX+$43)      ; test RECFLG - is it a PRINT type file.
+        RET     Z               ; return if so.
+        CALL    <A href="#L119F">L119F</a>           ; routine DEL-M-BUF reclaims the permanent
+                                ; channel thus losing the buffer contents.
+        RST     20H             ; Shadow Error Restart
+        DEFB    $16             ; 'Wrong file type'
+; -------------------------------------
+; THE <b><font color=#333388>'CLOSE NETWORK CHANNEL'</font></b> HOOK CODE
+; -------------------------------------
+; <font color=#339933>(Hook Code: $2E)</font>
+; Hook Code Only
+<a name="L1F18"></a>;; <b>CLOSE-NET</b>
+L1F18:  CALL    <A href="#L0FAE">L0FAE</a>           ; routine SEND-NEOF
+        PUSH    IX              ; pick up start address
+        POP     HL              ; of the channel.
+        LD      BC,$0114        ; bytes to reclaim.
+        RST     10H             ; CALBAS.
+        DEFW    $19E8           ; main RECLAIM-2.
+        RET                     ; return.
+; -------------------------------------
+; THE <b><font color=#333388>'GET PACKET FROM NETWORK'</font></b> ROUTINE
+; -------------------------------------
+; <font color=#339933>(Hook Code: $2F)</font>
+<a name="L1F25"></a>;; <b>GET-PACK</b>
+L1F25:  LD      A,($5CC6)       ; sv IOBORD
+        OUT     ($FE),A         ;
+        DI
+        CALL    <A href="#L0FD3">L0FD3</a>           ; routine WT-SC-E
+        JR      NC,<A href="#L1F3A">L1F3A</a>        ; forward to GP-ERROR
+        CALL    <A href="#L0EB5">L0EB5</a>           ; routine GET-NBLK
+        JR      NZ,<A href="#L1F3A">L1F3A</a>        ; forward to GP-ERROR
+        EI                      ;
+        AND     A               ;
+        JP      <A href="#L0D4D">L0D4D</a>           ; jump to BORD-REST
+; ---
+<a name="L1F3A"></a>;; <b>GP-ERROR</b>
+L1F3A:  SCF                     ;
+        EI                      ;
+        JP      <A href="#L0D4D">L0D4D</a>           ; jump to BORD-REST
+; ---------------------------
+; THE <b><font color=#333388>'READ SECTOR'</font></b> HOOK CODE
+; ---------------------------
+; <font color=#339933>(Hook Code: $28)</font>
+; fetches header from sector specified by CHREC.
+; If the sector is from a PRINT type file then it returns with success.
+; Otherwise if a program or code file the data area is 'cleared'.
+<a name="L1F3F"></a>;; <b>RD-SECTOR</b>
+L1F3F:  LD      HL,$00FF        ; ensure every sector is tried.
+                                ; <font color=#9900FF>Note.</font> was $F0 (240) in original ROM which
+                                ; would not be compatible with emulators.
+        LD      ($5CC9),HL      ; update temporary variable SECTOR
+<a name="L1F45"></a>;; <b>NO-GOOD</b>
+L1F45:  CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads the next header
+                                ; to pass the tape heads.
+        LD      A,(IX+$29)      ; fetch sector number from HDNUMB
+        CP      (IX+$0D)        ; compare with required sector in CHREC
+        JR      Z,<A href="#L1F57">L1F57</a>         ; forward, with match, to USE-C-RC
+        CALL    <A href="#L13F7">L13F7</a>           ; routine DEC-SECT decrements the counter.
+        JR      NZ,<A href="#L1F45">L1F45</a>        ; loop back, if not zero, to NO-GOOD
+        RST     20H             ; Shadow Error Restart
+        DEFB    $11             ; 'File not found'
+; ---
+<a name="L1F57"></a>;; <b>USE-C-RC</b>
+L1F57:  PUSH    IX              ; transfer channel base address
+        POP     HL              ; to the HL register.
+        LD      DE,$0043        ; offset to RECFLG
+        ADD     HL,DE           ; add to address start of record descriptor.
+        CALL    <A href="#L15EB">L15EB</a>           ; routine GET-M-BUF reads in the record
+                                ; descriptor and the 512 bytes of data.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R checksums the descriptor.
+        JR      NZ,<A href="#L1F75">L1F75</a>        ; forward, with error, to DEL-B-CT
+        LD      DE,$000F        ; additional offset to data.
+        ADD     HL,DE           ; add to address data.
+        CALL    <A href="#L142B">L142B</a>           ; routine CHKS-BUFF checksums the data buffer.
+        JR      NZ,<A href="#L1F75">L1F75</a>        ; forward, with error, to DEL-B-CT
+        OR      A               ; clear carry
+        BIT     2,(IX+$43)      ; test RECFLG - is this a PRINT file ?
+        RET     Z               ; return if so.
+<a name="L1F75"></a>;; <b>DEL-B-CT</b>
+L1F75:  CALL    <A href="#L1FD4">L1FD4</a>           ; routine CLR-BUFF sets descriptor and data
+                                ; contents to same values.
+        SCF                     ; signal error.
+        RET                     ; return from hook-code.
+; --------------------------------
+; THE <b><font color=#333388>'READ NEXT SECTOR'</font></b> HOOK CODE
+; --------------------------------
+; <font color=#339933>(Hook Code: $29)</font>
+; This hook code just reads the next header to pass the tape head and then,
+; without further qualification, reads the corresponding data using the
+; routine above. If not a PRINT file then the data is cleared.
+; It needlessly sets up a sector counter in the System Variable SECTOR.
+<a name="L1F7A"></a>;; <b>RD-NEXT</b>
+L1F7A:  LD      HL,$00FF        ; set count to 255. <font color=#9900FF>Note.</font> not used.
+        LD      ($5CC9),HL      ; insert in system variable SECTOR.
+        CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads the next header
+                                ; to pass the tape heads.
+        JR      <A href="#L1F57">L1F57</a>           ; back to USE-C-RC to read and validate the
+                                ; corresponding descriptor and data.
+; ----------------------------
+; THE <b><font color=#333388>'WRITE SECTOR'</font></b> HOOK CODE
+; ----------------------------
+; <font color=#339933>(Hook Code: $2A)</font>
+; writes to microdrive the sector in CHREC.
+<a name="L1F85"></a>;; <b>WR-SECTOR</b>
+L1F85:  LD      HL,$00FF        ; set counter to ensure at least one revolution
+        LD      ($5CC9),HL      ; of the tape and update SECTOR
+        PUSH    IX              ; transfer base address
+        POP     HL              ; of channel to HL.
+        LD      DE,$0037        ; offset to header preamble
+        ADD     HL,DE           ; add and
+        PUSH    HL              ; preserve location on machine stack.
+        LD      DE,$000C        ; offset past preamble to  RECFLG
+        ADD     HL,DE           ; the start of the record descriptor.
+        CALL    <A href="#L1426">L1426</a>           ; routine CHKS-HD-R insert checksum byte.
+        LD      DE,$000F        ; 15 byte offset to start  of data.
+        ADD     HL,DE           ; add to address first of 512 bytes.
+        CALL    <A href="#L142B">L142B</a>           ; routine CHKS-BUFF inserts buffer checksum.
+<a name="L1FA1"></a>;; <b>WR-S-1</b>
+L1FA1:  CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads any header.
+        LD      A,(IX+$29)      ; fetch sector from HDNUMB
+        CP      (IX+$0D)        ; compare to required sector in CHREC
+        JR      Z,<A href="#L1FB3">L1FB3</a>         ; forward, with match, to WR-S-2
+        CALL    <A href="#L13F7">L13F7</a>           ; routine DEC-SECT decrements the counter
+        JR      NZ,<A href="#L1FA1">L1FA1</a>        ; back, if not zero, to WR-S-1
+; else the header was not found after a complete tape revolution.
+        RST     20H             ; Shadow Error Restart
+        DEFB    $11             ; File not found
+; ---
+<a name="L1FB3"></a>;; <b>WR-S-2</b>
+L1FB3:  IN      A,($EF)         ; read microdrive port.
+        AND     $01             ; isolate 'write prot.' bit.
+        JR      NZ,<A href="#L1FBB">L1FBB</a>        ; forward, if not, to WR-S-3
+        RST     20H             ; Shadow Error Restart
+        DEFB    $0E             ; Drive 'write' protected
+; ---
+<a name="L1FBB"></a>;; <b>WR-S-3</b>
+L1FBB:  LD      A,$E6           ; enable writing
+        OUT     ($EF),A         ; output to port.
+        LD      BC,$0168        ; set delay to 360
+        CALL    <A href="#L1652">L1652</a>           ; routine DELAY-BC pauses briefly as the
+                                ; record now approaches the tape heads.
+        POP     HL              ; restore pointer to RECFLG
+        CALL    <A href="#L15B3">L15B3</a>           ; routine OUT-M-BUF writes descriptor and
+                                ; data buffer.
+        LD      A,$EE           ; disable writing
+        OUT     ($EF),A         ; output to port.
+        CALL    <A href="#L13C4">L13C4</a>           ; routine CHECK-MAP fetches bit mask for map
+                                ; location addressed by HL into B register.
+        LD      A,B             ; transfer mask to accumulator
+        OR      (HL)            ; combine with any set bits already there.
+        LD      (HL),A          ; update map marking sector used.
+        RET                     ; return.
+; -----------------------------------
+; THE <b><font color=#333388>'CLEAR BUFFER CONTENTS'</font></b> ROUTINE
+; -----------------------------------
+; This routine sets the contents of the 14 byte record descriptor and
+; the 512 byte data buffer to the same value so that they are unreadable.
+; This is invoked when the possibility that a secret file, whose name begins
+; with CHR$ 0 has been read.
+<a name="L1FD4"></a>;; <b>CLR-BUFF</b>
+L1FD4:  PUSH    IX              ; transfer the channel base
+        POP     HL              ; address to HL.
+        LD      DE,$0028        ; offset to HDFLAG.
+        ADD     HL,DE           ; add to base address.
+        LD      D,H             ; transfer same
+        LD      E,L             ; address to DE and
+        INC     DE              ; make one higher.
+        LD      BC,$0229        ; set counter to 553 bytes.
+        LDIR                    ; fill with HDFLAG contents.
+        RET                     ; return.
+; ---------------------------------------
+; THE <b><font color=#333388>'FETCH RECORD DESCRIPTOR'</font></b> HOOK CODE
+; ---------------------------------------
+; <font color=#339933>(Hook Code: $33)</font>
+; <font color=#9900FF>Note.</font> new in this ROM.
+; This Hook Code reads the next header and corresponding record descriptor
+; returning with carry flag set with header mismatch or if the name starts
+; with CHR$ 0 and should therefore be secret.
+<a name="L1FE4"></a>;; <b>GET-DESC</b>
+L1FE4:  CALL    <A href="#L13A9">L13A9</a>           ; routine GET-M-HD2 reads the next 14-byte
+                                ; header to pass the tape heads.
+        CALL    <A href="#L1E5E">L1E5E</a>           ; routine G-RDES reads the corresponding
+                                ; 14-byte record descriptor for this sector.
+        JR      NZ,<A href="#L1FF1">L1FF1</a>        ; forward, with checksum error, to NOT-RECV
+; a valid header and matching descriptor has been read.
+        LD      A,(IX+$47)      ; fetch first character of RECNAM.
+        OR      A               ; test for CHR$ 0.
+        RET     NZ              ; return if not a secret file.
+; but if a secret file then ensure that the 14 descriptor bytes (read) and
+; the 512 buffer bytes (not read) are cleared to the same value.
+<a name="L1FF1"></a>;; <b>NOT-RECV</b>
+L1FF1:  CALL    <A href="#L1FD4">L1FD4</a>           ; routine CLR-BUFF (above).
+        SCF                     ; signal error.
+        RET                     ; return from hook code.
+; --------------------------------
+; THE <b><font color=#333388>'OPEN "B" CHANNEL'</font></b> HOOK CODE
+; --------------------------------
+; <font color=#339933>(Hook Code: $34)</font>
+; New in this ROM.
+<a name="L1FF6"></a>;; <b>OP-B-CHAN</b>
+L1FF6:  LD      A,$42           ; letter "B"
+        LD      ($5CD9),A       ; place in system variable L_STR1
+        CALL    <A href="#L0B17">L0B17</a>           ; routine OP-RS-CH opens an RS232 channel.
+        RET                     ; return.
+; ---
+        DEFB    $FF             ; spare
+; ---
+.end
+; -----------------------------
+; THE <b><font color=#333388>'SHADOW'</font></b> SYSTEM VARIABLES
+; -----------------------------
+;
+; X1  23734 $5CB6  FLAGS3                 ; IY+$7C - Flags
+; X2  23735 $5CB7  VECTOR                 ; Address used to extend BASIC.
+; X10 23737 $5CB9  SBRT                   ; 10 bytes of Z80 code to Page ROM.
+; 2   23747 $5CC3  BAUD                   ; BAUD=(3500000/(26*baud rate)) -2
+; 1   23749 $5CC5  NTSTAT                 ; Own network station number.
+; 1   23750 $5CC6  IOBORD                 ; Border colour during I/O
+; N2  23751 $5CC7  SER_FL                 ; 2 byte workspace used by RS232
+; N2  23753 $5CC9  SECTOR                 ; 2 byte workspace used by Microdrive.
+; N2  23755 $5CCB  CHADD_                 ; Temporary store for CH_ADD
+; 1   23757 $5CCC  NTRESP                 ; Store for network response code.
+; --  ----- -----  ------                 ; ---------------------------------
+; 1   23758 $5CCD  NTDEST                 ;  Destination station number 0 - 64.
+; 1   23759 $5CCE  NTSRCE                 ;  Source station number.
+; X2  23760 $5CD0  NTNUMB                 ;  Network block number 0 - 65535
+; N1  23762 $5CD2  NTTYPE                 ;  Header type block.
+; X1  23763 $5CD3  NTLEN                  ;  Data block length 0 - 255.
+; N1  23764 $5CD4  NTDCS                  ;  Data block checksum.
+; N1  23765 $5CD5  NTHDS                  ;  Header block checksum.
+; --  ----- -----  ------                 ; ---------------------------------
+; N2  23766 $5CD6  D_STR1                 ; 2 byte drive number 1 - 8.
+; N1  23768 $5CD8  S_STR1                 ; Stream number 1 - 15. [ also 0 ]
+; N1  23769 $5CD9  L_STR1                 ; Device type "M", "N", "T" or "B"
+; N2  23770 $5CDA  N-STR1                 ; Length of filename.
+; N2  23772 $5CDC             (dynamic)   ; Address of filename.
+; --  ----- -----  ------                 ; ---------------------------------
+; N1  23774 $5CDE  D_STR2                 ; 2 byte drive   ; File type.
+; N1  23775 $5CDF                         ; number.        ; Length of
+; N1  23776 $5CE0  S_STR2                 ; Stream number. ; Data.
+; N1  23777 $5CE1  L_STR2                 ; Device type.   ; Start of
+; N1  23778 $5CE2  N-STR2                 ; Length of      ; data.   \
+; N1  23779 $5CE3                         ; filename.      ; Program  \
+; N1  23780 $5CE4             (dynamic)   ; Address of     ; length. ; Start of
+; N1  23781 $5CE5             (dynamic)   ; filename       ;         ; data.
+; --  ----- -----  ------                 ; ---------------------------------
+; N1  23782 $5CE6  HD_00                  ; File type .      _
+; N2  23783 $5CE7  HD_0B                  ; Length of data.   /\
+; N2  23785 $5CE9  HD_0D                  ; Start of data.   /
+; N2  23787 $5CEB  HD_0F                  ; Program length. /
+; N2  23789 $5CED  HD_11                  ; Line number.
+; --  ----- -----  ------                 ; ---------------------------------
+; 1   23791 $5CEF  COPIES                 ; Number of copies made by SAVE.
+; --  ----- -----  ------                 ; ---------------------------------
+; <font color=#9900FF>Note.</font> the System Variables HD_00 to HD_11 take their names from their
+; position in the standard audio tape header. The ten bytes HD_01 to HD_0A
+; would be the tape filename and are not held within the above area.
+; The area D_STR2 is multipurpose and sometimes the HD_?? variables are
+; copied to this region and sometimes the D_STR1 variables are copied there.
+; ----------------------------
+; THE <b><font color=#333388>'MICRODRIVE MAPS'</font></b> FORMAT
+; ----------------------------
+;
+; The creation of the extra system variables moves the start of CHANS up to
+; address 23792.  It is at this location that the first of a possible eight
+; Microdrive Maps will be created.  Each map is 32 bytes in size containing
+; 256 bits for each possible sector and as each map is created, CHANS moves
+; up by another 32 bytes.
+; 10000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
+; 00000000 00000000 00000000 00000000 00010101 01010100 00000000 00000000
+; 00000000 01100000 00000000 00000000 00000000 00000000 00000111 11111111
+; 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111
+; <font color=#9900FF>Note.</font> The continuous loop tape is formatted in such a way that sector $FE
+; is written first and sector $01 is the last to be written. Sectors $00 and
+; $FF are therefore always unavailable.  As there is only room for about 180
+; sectors on a 100 foot long tape, the higher numbered sectors are later
+; overwritten by the lower numbered sectors.
+; Where the tape is spliced together one or two bad sectors will appear.
+; When saving bytes there isn't enough time to copy the next 512 bytes from
+; the program/code area to the buffer between sectors so a program or
+; code/data block is written to alternating sectors as with the 3K example
+; above.  As the tape cartridge fills up it becomes more difficult to find
+; usable sectors and LOAD/SAVE operations take longer.
+; A growing number of Spectrum emulators feature the microdrives and they
+; usually make available all 254 sectors so a typical cartridge will hold 126
+; Kilobytes compared to say 92 K on real hardware.
+;
+; During a LOAD operation the entire sector map is pushed on the machine stack
+; and the microdrive map is used to map loaded records after which the previous
+; map is 'popped' of the stack and reverts to mapping sectors again.
+;
+; ------------------------------
+; THE <b><font color=#333388>'STANDARD CHANNELS'</font></b> FORMAT
+; ------------------------------
+; The twenty bytes of the standard channels as set up my Main ROM.
+;
+; CHANS                   $09F4           ; PRINT-OUT
+;                         $10A8           ; KEY-INPUT
+;                         $4B             ; 'K'
+;
+;                         $09F4           ; PRINT-OUT
+;                         $15C4           ; REPORT-J
+;                         $53             ; 'S'
+;
+;                         $0F81           ; ADD-CHAR
+;                         $15C4           ; REPORT-J
+;                         $52             ; 'R'
+;
+;                         $09F4           ; PRINT-OUT
+;                         $15C4           ; REPORT-J
+;                         $50             ; 'P'
+;
+;                         $80             ; End Marker
+; -------------------------------
+; THE <b><font color=#333388>'MICRODRIVE CHANNEL'</font></b> FORMAT
+; -------------------------------
+;
+;   2 IX+$00              $0008           ; main ERROR-1
+;   2 IX+$02              $0008           ; main ERROR-1
+;   1 IX+$04              $CD             ; inverted or regular "M" character
+;   2 IX+$05              $12B3           ; MCHAN-OUT
+;   2 IX+$07              $11FD           ; M-INPUT
+;   2 IX+$09              $0253           ; length of channel.
+;   2 IX+$0B  CHBYTE      $0000           ; position of next byte rec'd/stored
+;   1 IX+$0D  CHREC       $00             ; record number, also temporary sector
+;  10 IX+$0E  CHNAME      "          "    ; filename with trailing spaces.
+;   1 IX+$18  CHFLAG      %0000000x       ; bit 0 used
+;   1 IX+$19  CHDRIV                      ; drive number 0 - 7.
+;   2 IX+$1A  CHMAP                       ; address of MAP for this microdrive.
+; ------------------------------------------------------------------------------
+;  12 IX+$1C                              ; 12 bytes of header preamble
+; ------------------------------------------------------------------------------
+;   1 IX+$28  HDFLAG                      ; Flag byte.
+;                                         ; bit 0 set indicates a header.
+;   1 IX+$29  HDNUMB                      ; Sector number. [1-254]
+;   2 IX+$2A                              ; Two unused bytes.
+;  10 IX+$2C  HDNAME                      ; Cartridge name with trailing spaces.
+;   1 IX+$36  HDCHK                       ; Header checksum.
+; ------------------------------------------------------------------------------
+;  12 IX+$37                              ; 12 bytes of data block preamble.
+; ------------------------------------------------------------------------------
+;   1 IX+$43  RECFLG                      ; Flag byte.
+;                                         ; bit 0 reset indicates a record.
+;                                         ; bit 1 reset no EOF, set EOF
+;                                         ; bit 2 reset indicates a PRINT FILE
+;   1 IX+$44  RECNUM                      ; Record number in the range 0-255
+;   2 IX+$45  RECLEN                      ; Number of databytes in record 0-512.
+;  10 IX+$47  RECNAM                      ; Filename with trailing spaces.
+;   1 IX+$51  DESCHK                      ; Checksum of the preceding 14 bytes
+; ------------------------------------------------------------------------------
+; 512 IX+$52  CHDATA                      ; the 512 bytes of data.
+;   1 +$0252  DCHK                        ; Checksum of preceding 512 bytes.
+; ----------------------------
+; THE <b><font color=#333388>'NETWORK CHANNEL'</font></b> FORMAT
+; ----------------------------
+;
+;   2 IX+$00              $0008           ; main ERROR-1
+;   2 IX+$02              $0008           ; main ERROR-1
+;   1 IX+$04              $4E             ; "N" character
+;   2 IX+$05              $0E09           ; NCHAN-OUT
+;   2 IX+$07              $0DA9           ; N-INPUT
+;   2 IX+$09              $0114           ; Length of channel 276 bytes.
+;   1 IX+$0B NCIRIS                       ; The destination station number.
+;   1 IX+$0C NCSELF                       ; This Spectrum's station number.
+;   2 IX+$0D NCNUMB                       ; The block number.
+;   1 IX+$0F NCTYPE                       ; The packet type code . 0 data, 1 EOF
+;   1 IX+$10 NCOBL                        ; Number of bytes in data block.
+;   1 IX+$11 NCDCS                        ; The data checksum.
+;   1 IX+$12 NCHCS                        ; The header checksum.
+;   1 IX+$13 NCCUR                        ; The position of last buffer char taken
+;   1 IX+$14 NCIBL                        ; Number of bytes in the input buffer.
+;   1 IX+$15 NCB                          ; A 255 byte data buffer.
+; ------------------------------
+; THE <b><font color=#333388>'RS232 "T" CHANNEL'</font></b> FORMAT
+; ------------------------------
+;
+;   2 IX+$00              $0008           ; main ERROR-1
+;   2 IX+$02              $0008           ; main ERROR-1
+;   1 IX+$04              $54             ; "T" character
+;   2 IX+$05              $0C3A           ; TCHAN-OUT
+;   2 IX+$07              $0B76           ; T-INPUT
+;   2 IX+$09              $000B           ; length of channel.
+; ------------------------------
+; THE <b><font color=#333388>'RS232 "B" CHANNEL'</font></b> FORMAT
+; ------------------------------
+; created by overwriting a "T" channel
+;
+;   2 IX+$00              $0008           ; main ERROR-1
+;   2 IX+$02              $0008           ; main ERROR-1
+;   1 IX+$04              $42             ; "B" character
+;   2 IX+$05              $0D07           ; BCHAN-OUT
+;   2 IX+$07              $0B7C           ; B-INPUT
+;   2 IX+$09              $000B           ; length of channel.
+; Acknowledgements
+; ----------------
+; Dr Ian Logan          for main ROM labels ( and half on Interface 1)
+; Dr Frank O'Hara       for main ROM labels.
+; Gianluca Carri        for Interface 1 v1.2 labels
+; Credits
+; -------
+; Jonathan Needle       for requesting said labels on comp.sys.sinclair
+;                       thereby kick-starting this project.
+;                       Also for the Interface1-aware Spectaculator emulator
+;                       and help with PORTS.
+; Paul Dunn             for help with PORTS and the SPIN emulator.
+; Chris Born            for documentation.
+</PRE>
+</HTML>