80-Bus News

  

November-December 1983, Volume 2, Issue 6











Page 33 of 67











Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    42

EC39 CD90E6     NEDMOR: CALL    CHKSYN          ; Check for comma between items
EC3C 2C                 DEFB    ","
EC3D CD2DEF     GTVLUS: CALL    GETVAR          ; Get variable name
EC40 E3                 EX      (SP),HL         ; Save code str" , Get pointer
EC41 D5                 PUSH    DE              ; Save variable address
EC42 7E                 LD      A,(HL)          ; Get next "INPUT"/"DATA" byte
EC43 FE2C               CP      ","             ; Comma?
EC45 CA65EC             JP      Z,ANTVLU        ; Yes - Get another value
EC48 3ACD10             LD      A,(READFG)      ; Is it READ?
EC4B B7                 OR      A
EC4C C2D2EC             JP      NZ,FDTLP        ; Yes - Find next DATA stmt
EC4F 3E3F               LD      A,"?"           ; More INPUT needed
EC51 CD9BE6             CALL    OUTC            ; Output character
EC54 CDFCE4             CALL    PROMPT          ; Get INPUT with prompt
EC57 D1                 POP     DE              ; Variable address
EC58 C1                 POP     BC              ; Code string address
EC59 DA77E8             JP      C,INPBRK        ; Break pressed
EC5C 23                 INC     HL              ; Point to next DATA byte
EC5D 7E                 LD      A,(HL)          ; Get byte
EC5E B7                 OR      A               ; Is it zero (No input) ?
EC5F 2B                 DEC     HL              ; Back space INPUT pointer
EC60 C5                 PUSH    BC              ; Save code string address
EC61 CA6FEA             JP      Z,NXTDTA        ; Find end of buffer
EC64 D5                 PUSH    DE              ; Save variable address
EC65 3AAD10     ANTVLU: LD      A,(TYPE)        ; Check data type
EC68 B7                 OR      A               ; Is it numeric?
EC69 CA8FEC             JP      Z,INPBIN        ; Yes - Convert to binary
EC6C CD36E8             CALL    GETCHR          ; Get next character
EC6F 57                 LD      D,A             ; Save input character
EC70 47                 LD      B,A             ; Again
EC71 FE22               CP      '"'             ; Start of literal sting?
EC73 CA83EC             JP      Z,STRENT        ; Yes - Create string entry
EC76 3ACD10             LD      A,(READFG)      ; "READ" or "INPUT" ?
EC79 B7                 OR      A
EC7A 57                 LD      D,A             ; Save 00 if "INPUT"
EC7B CA80EC             JP      Z,ITMSEP        ; "INPUT" - End with 00
EC7E 163A               LD      D,":"           ; "DATA" - End with 00 or ":"
EC80 062C       ITMSEP: LD      B,","           ; Item separator
EC82 2B                 DEC     HL              ; Back space for DTSTR
EC83 CDD2F1     STRENT: CALL    DTSTR           ; Get string terminated by D
EC86 EB                 EX      DE,HL           ; String address to DE
EC87 219AEC             LD      HL,LTSTND       ; Where to go after LETSTR
EC8A E3                 EX      (SP),HL         ; Save HL , get input pointer
EC8B D5                 PUSH    DE              ; Save address of string
EC8C C3A2EA             JP      LETSTR          ; Assign string to variable

Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    43

EC8F CD36E8     INPBIN: CALL    GETCHR          ; Get next character
EC92 CD1AF9             CALL    ASCTFP          ; Convert ASCII to FP number
EC95 E3                 EX      (SP),HL         ; Save input ptr, Get var addr
EC96 CD6BF8             CALL    FPTHL           ; Move FPREG to variable
EC99 E1                 POP     HL              ; Restore input pointer
EC9A 2B         LTSTND: DEC     HL              ; DEC 'cos GETCHR INCs
EC9B CD36E8             CALL    GETCHR          ; Get next character
EC9E CAA6EC             JP      Z,MORDT         ; End of line - More needed?
ECA1 FE2C               CP      ","             ; Another value?
ECA3 C2ECEB             JP      NZ,BADINP       ; No - Bad input
ECA6 E3         MORDT:  EX      (SP),HL         ; Get code string address
ECA7 2B                 DEC     HL              ; DEC 'cos GETCHR INCs
ECA8 CD36E8             CALL    GETCHR          ; Get next character
ECAB C239EC             JP      NZ,NEDMOR       ; More needed - Get it
ECAE D1                 POP     DE              ; Restore DATA pointer
ECAF 3ACD10             LD      A,(READFG)      ; "READ" or "INPUT" ?
ECB2 B7                 OR      A
ECB3 EB                 EX      DE,HL           ; DATA pointer to HL
ECB4 C25CE8             JP      NZ,UPDATA       ; Update DATA pointer if "READ"
ECB7 D5                 PUSH    DE              ; Save code string address
ECB8 B6                 OR      (HL)            ; More input given?
ECB9 21C1EC             LD      HL,EXTIG        ; "?Extra ignored" message
ECBC C410F2             CALL    NZ,PRS          ; Output string if extra given
ECBF E1                 POP     HL              ; Restore code string address
ECC0 C9                 RET

ECC1 3F457874   EXTIG:  DEFB    "?Extra ignored",CR,LF,0

ECD2 CD70EA     FDTLP:  CALL    DATA            ; Get next statement
ECD5 B7                 OR      A               ; End of line?
ECD6 C2EBEC             JP      NZ,FANDT        ; No - See if DATA statement
ECD9 23                 INC     HL
ECDA 7E                 LD      A,(HL)          ; End of program?
ECDB 23                 INC     HL
ECDC B6                 OR      (HL)            ; 00 00 Ends program
ECDD 1E06               LD      E,OD            ; ?OD Error
ECDF CAC1E3             JP      Z,ERROR         ; Yes - Out of DATA
ECE2 23                 INC     HL
ECE3 5E                 LD      E,(HL)          ; LSB of line number
ECE4 23                 INC     HL
ECE5 56                 LD      D,(HL)          ; MSB of line number
ECE6 EB                 EX      DE,HL
ECE7 22C910             LD      (DATLIN),HL     ; Set line of current DATA item
ECEA EB                 EX      DE,HL
ECEB CD36E8     FANDT:  CALL    GETCHR          ; Get next character
ECEE FE83               CP      ZDATA           ; "DATA" token
ECF0 C2D2EC             JP      NZ,FDTLP        ; No "DATA" - Keep looking
ECF3 C365EC             JP      ANTVLU          ; Found - Convert input


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











Page 33 of 67