80-Bus News


November–December 1983 · Volume 2 · Issue 6

Page 31 of 67


Part 4

By Carl Lloyd–Parker

Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    39

EB1F 2B         MRPRNT: DEC     HL              ; DEC 'cos GETCHR INCs
EB20 CD36E8             CALL    GETCHR          ; Get next character
EB23 CA81EB     PRINT:  JP      Z,PRNTCR        ; CRLF if just PRINT
EB26 C8         PRNTLP: RET     Z               ; End of list - Exit
EB27 FEA5               CP      ZTAB            ; "TAB(" token?
EB29 CAAFEB             JP      Z,DOTAB         ; Yes - Do TAB routine
EB2C FEA8               CP      ZSPC            ; "SPC(" token?
EB2E CAAFEB             JP      Z,DOTAB         ; Yes - Do SPC routine
EB31 E5                 PUSH    HL              ; Save code string address
EB32 FE2C               CP      ","             ; Comma?
EB34 CA98EB             JP      Z,DOCOM         ; Yes - Move to next zone
EB37 FE3B               CP      ";"             ; Semi-colon?
EB39 CAD2EB             JP      Z,NEXITM        ; Do semi-colon routine
EB3C C1                 POP     BC              ; Code string address to BC
EB3D CD5AED             CALL    EVAL            ; Evaluate expression
EB40 E5                 PUSH    HL              ; Save code string address
EB41 3AAD10             LD      A,(TYPE)        ; Get variable type
EB44 B7                 OR      A               ; Is it a string variable?
EB45 C26DEB             JP      NZ,PRNTST       ; Yes - Output string contents
EB48 CDB8F9             CALL    NUMASC          ; Convert number to text
EB4B CDCEF1             CALL    CRTST           ; Create temporary string
EB4E 3620               LD      (HL)," "        ; Followed by a space
EB50 2AE410             LD      HL,(FPREG)      ; Get length of output
EB53 34                 INC     (HL)            ; Plus 1 for the space
EB54 2AE410             LD      HL,(FPREG)      ; < Not needed >
EB57 3A4210             LD      A,(LWIDTH)      ; Get width of line
EB5A 47                 LD      B,A             ; To B
EB5B 04                 INC     B               ; Width 255 (No limit)?
EB5C CA69EB             JP      Z,PRNTNB        ; Yes - Output number string
EB5F 04                 INC     B               ; Adjust it
EB60 3AAB10             LD      A,(CURPOS)      ; Get cursor position
EB63 86                 ADD     A,(HL)          ; Add length of string
EB64 3D                 DEC     A               ; Adjust it
EB65 B8                 CP      B               ; Will output fit on this line?
EB66 D481EB             CALL    NC,PRNTCR       ; No - CRLF first
EB69 CD13F2     PRNTNB: CALL    PRS1            ; Output string at (HL)
EB6C AF                 XOR     A               ; Skip CALL by setting "Z" flag
EB6D C413F2     PRNTST: CALL    NZ,PRS1         ; Output string at (HL)
EB70 E1                 POP     HL              ; Restore code string address
EB71 C31FEB             JP      MRPRNT          ; See if more to PRINT

EB74 3AAB10     STTLIN: LD      A,(CURPOS)      ; Make sure on new line
EB77 B7                 OR      A               ; Already at start?
EB78 C8                 RET     Z               ; Yes - Do nothing
EB79 C381EB             JP      PRNTCR          ; Start a new line

Go to part 3 of NASCOM ROM BASIC dis-assembled.

NASCOM ROM BASIC dis-assembled is available in ASM and LST file format.

Page 31 of 67