80-Bus News

  

November–December 1983, Volume 2, Issue 6











Page 32 of 67











Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    40

EB7C 3600       ENDINP: LD      (HL),0          ; Mark end of buffer
EB7E 216010             LD      HL,BUFFER-1     ; Point to buffer
EB81 3E0D       PRNTCR: LD      A,CR            ; Load a CR
EB83 CD9BE6             CALL    OUTC            ; Output character
EB86 AF         DONULL: XOR     A               ; Set to position 0
EB87 32AB10             LD      (CURPOS),A      ; Store it
EB8A 3A4110             LD      A,(NULLS)       ; Get number of nulls
EB8D 3D         NULLP:  DEC     A               ; Count them
EB8E C8                 RET     Z               ; Return if done
EB8F F5                 PUSH    AF              ; Save count
EB90 AF                 XOR     A               ; Load a null
EB91 CD9BE6             CALL    OUTC            ; Output it
EB94 F1                 POP     AF              ; Restore count
EB95 C38DEB             JP      NULLP           ; Keep counting

EB98 3A4310     DOCOM:  LD      A,(COMMAN)      ; Get comma width
EB9B 47                 LD      B,A             ; Save in B
EB9C 3AAB10             LD      A,(CURPOS)      ; Get current position
EB9F B8                 CP      B               ; Within the limit?
EBA0 D481EB             CALL    NC,PRNTCR       ; No - output CRLF
EBA3 D2D2EB             JP      NC,NEXITM       ; Get next item
EBA6 D60E       ZONELP: SUB     14              ; Next zone of 14 characters
EBA8 D2A6EB             JP      NC,ZONELP       ; Repeat if more zones
EBAB 2F                 CPL                     ; Number of spaces to output
EBAC C3C7EB             JP      ASPCS           ; Output them

EBAF F5         DOTAB:  PUSH    AF              ; Save token
EBB0 CD81F4             CALL    FNDNUM          ; Evaluate expression
EBB3 CD90E6             CALL    CHKSYN          ; Make sure ")" follows
EBB6 29                 DEFB    ")"
EBB7 2B                 DEC     HL              ; Back space on to ")"
EBB8 F1                 POP     AF              ; Restore token
EBB9 D6A8               SUB     ZSPC            ; Was it "SPC(" ?
EBBB E5                 PUSH    HL              ; Save code string address
EBBC CAC2EB             JP      Z,DOSPC         ; Yes - Do "E" spaces
EBBF 3AAB10             LD      A,(CURPOS)      ; Get current position
EBC2 2F         DOSPC:  CPL                     ; Number of spaces to print to
EBC3 83                 ADD     A,E             ; Total number to print
EBC4 D2D2EB             JP      NC,NEXITM       ; TAB < Current POS(X)
EBC7 3C         ASPCS:  INC     A               ; Output A spaces
EBC8 47                 LD      B,A             ; Save number to print
EBC9 3E20               LD      A," "           ; Space
EBCB CD9BE6     SPCLP:  CALL    OUTC            ; Output character in A
EBCE 05                 DEC     B               ; Count them
EBCF C2CBEB             JP      NZ,SPCLP        ; Repeat if more
EBD2 E1         NEXITM: POP     HL              ; Restore code string address
EBD3 CD36E8             CALL    GETCHR          ; Get next character
EBD6 C326EB             JP      PRNTLP          ; More to print
Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    41

EBD9 3F526564   REDO:   DEFB    "?Redo from start",CR,LF,0

EBEC 3ACD10     BADINP: LD      A,(READFG)      ; READ or INPUT?
EBEF B7                 OR      A
EBF0 C2A7E3             JP      NZ,DATSNR       ; READ - ?SN Error
EBF3 C1                 POP     BC              ; Throw away code string addr
EBF4 21D9EB             LD      HL,REDO         ; "Redo from start" message
EBF7 CD10F2             CALL    PRS             ; Output string
EBFA C3F8E4             JP      DOAGN           ; Do last INPUT again

EBFD CD7BF1     INPUT:  CALL    IDTEST          ; Test for illegal direct
EC00 7E                 LD      A,(HL)          ; Get character after "INPUT"
EC01 FE22               CP      '"'             ; Is there a prompt string?
EC03 3E00               LD      A,0             ; Clear A and leave flags
EC05 324510             LD      (CTLOFG),A      ; Enable output
EC08 C217EC             JP      NZ,NOPMPT       ; No prompt - get input
EC0B CDCFF1             CALL    QTSTR           ; Get string terminated by '"'
EC0E CD90E6             CALL    CHKSYN          ; Check for ";" after prompt
EC11 3B                 DEFB    ";"
EC12 E5                 PUSH    HL              ; Save code string address
EC13 CD13F2             CALL    PRS1            ; Output prompt string
EC16 3E                 DEFB    (LD A,n)        ; Skip "PUSH HL"
EC17 E5         NOPMPT: PUSH    HL              ; Save code string address
EC18 CDFCE4             CALL    PROMPT          ; Get input with "? " prompt
EC1B C1                 POP     BC              ; Restore code string address
EC1C DA77E8             JP      C,INPBRK        ; Break pressed - Exit
EC1F 23                 INC     HL              ; Next byte
EC20 7E                 LD      A,(HL)          ; Get it
EC21 B7                 OR      A               ; End of line?
EC22 2B                 DEC     HL              ; Back again
EC23 C5                 PUSH    BC              ; Re-save code string address
EC24 CA6FEA             JP      Z,NXTDTA        ; Yes - Find next DATA stmt
EC27 362C               LD      (HL),","        ; Store comma as separator
EC29 C331EC             JP      NXTITM          ; Get next item

EC2C E5         READ:   PUSH    HL              ; Save code string address
EC2D 2ADC10             LD      HL,(NXTDAT)     ; Next DATA statement
EC30 F6                 DEFB    (OR n)          ; Flag "READ"
EC31 AF         NXTITM: XOR     A               ; Flag "INPUT"
EC32 32CD10             LD      (READFG),A      ; Save "READ"/"INPUT" flag
EC35 E3                 EX      (SP),HL         ; Get code str' , Save pointer
EC36 C33DEC             JP      GTVLUS          ; Get values

This is an OCR’d version of the scanned page and likely contains recognition errors.

NASCOM ROM BASIC source code is available in ASM and LST file format.











Page 32 of 67