80-Bus News

  

January-February 1984, Volume 3, Issue 1











Page 25 of 55











Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    57

F0D0 2ADA10     FRE:    LD      HL,(ARREND)     ; Start of free memory
F0D3 EB                 EX      DE,HL           ; To DE
F0D4 210000             LD      HL,0            ; End of free memory
F0D7 39                 ADD     HL,SP           ; Current stack value
F0D8 3AAD10             LD      A,(TYPE)        ; Dummy argument type
F0DB B7                 OR      A
F0DC CAECF0             JP      Z,FRENUM        ; Numeric - Free variable space
F0DF CD53F3             CALL    GSTRCU          ; Current string to pool
F0E2 CD53F2             CALL    GARBGE          ; Garbage collection
F0E5 2A5A10             LD      HL,(STRSPC)     ; Bottom of string space in use
F0E8 EB                 EX      DE,HL           ; To DE
F0E9 2AC310             LD      HL,(STRBOT)     ; Bottom of string space
F0EC 7D         FRENUM: LD      A,L             ; Get LSB of end
F0ED 93                 SUB     E               ; Subtract LSB of beginning
F0EE 4F                 LD      C,A             ; Save difference if C
F0EF 7C                 LD      A,H             ; Get MSB of end
F0F0 9A                 SBC     A,D             ; Subtract MSB of beginning
F0F1 41         ACPASS: LD      B,C             ; Return integer AC
F0F2 50         ABPASS: LD      D,B             ; Return integer AB
F0F3 1E00               LD      E,0
F0F5 21AD10             LD      HL,TYPE         ; Point to type
F0F8 73                 LD      (HL),E          ; Set type to numeric
F0F9 0690               LD      B,80H+16        ; 16 bit integer
F0FB C32AF8             JP      RETINT          ; Return the integr

F0FE 3AAB10     POS:    LD      A,(CURPOS)      ; Get cursor position
F101 47         PASSA:  LD      B,A             ; Put A into AB
F102 AF                 XOR     A               ; Zero A
F103 C3F2F0             JP      ABPASS          ; Return integer AB

F106 CD89F1     DEF:    CALL    CHEKFN          ; Get "FN" and name
F109 CD7BF1             CALL    IDTEST          ; Test for illegal direct
F10C 0170EA             LD      BC,DATA         ; To get next statement
F10F C5                 PUSH    BC              ; Save address for RETurn
F110 D5                 PUSH    DE              ; Save address of function ptr
F111 CD90E6             CALL    CHKSYN          ; Make sure "(" follows
F114 28                 DEFB    "("
F115 CD2DEF             CALL    GETVAR          ; Get argument variable name
F118 E5                 PUSH    HL              ; Save code string address
F119 EB                 EX      DE,HL           ; Argument address to HL
F11A 2B                 DEC     HL
F11B 56                 LD      D,(HL)          ; Get first byte of arg name
F11C 2B                 DEC     HL
F11D 5E                 LD      E,(HL)          ; Get second byte of arg name
F11E E1                 POP     HL              ; Restore code string address
F11F CD44ED             CALL    TSTNUM          ; Make sure numeric argument
F122 CD90E6             CALL    CHKSYN          ; Make sure ")" follows
F125 29                 DEFB    ")"
F126 CD90E6             CALL    CHKSYN          ; Make sure "=" follows
F129 B4                 DEFB    ZEQUAL          ; "=" token
F12A 44                 LD      B,H             ; Code string address to BC
F12B 4D                 LD      C,L
F12C E3                 EX      (SP),HL         ; Save code str , Get FN ptr
F12D 71                 LD      (HL),C          ; Save LSB of FN code string
F12E 23                 INC     HL
F12F 70                 LD      (HL),B          ; Save MSB of FN code string
F130 C3C8F1             JP      SVSTAD          ; Save address and do function

Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    58

F133 CD89F1     DOFN:   CALL    CHEKFN          ; Make sure FN follows
F136 D5                 PUSH    DE              ; Save function pointer address
F137 CD09EE             CALL    EVLPAR          ; Evaluate expression in "()"
F13A CD44ED             CALL    TSTNUM          ; Make sure numeric result
F13D E3                 EX      (SP),HL         ; Save code str , Get FN ptr
F13E 5E                 LD      E,(HL)          ; Get LSB of FN code string
F13F 23                 INC     HL
F140 56                 LD      D,(HL)          ; Get MSB of FN code string
F141 23                 INC     HL
F142 7A                 LD      A,D             ; And function DEFined?
F143 B3                 OR      E
F144 CAB9E3             JP      Z,UFERR         ; No - ?UF Error
F147 7E                 LD      A,(HL)          ; Get LSB of argument address
F148 23                 INC     HL
F149 66                 LD      H,(HL)          ; Get MSB of argument address
F14A 6F                 LD      L,A             ; HL = Arg variable address
F14B E5                 PUSH    HL              ; Save it
F14C 2ADE10             LD      HL,(FNRGNM)     ; Get old argument name
F14F E3                 EX      (SP),HL ;       ; Save old , Get new
F150 22DE10             LD      (FNRGNM),HL     ; Set new argument name
F153 2AE210             LD      HL,(FNARG+2)    ; Get LSB,NLSB of old arg value
F156 E5                 PUSH    HL              ; Save it
F157 2AE010             LD      HL,(FNARG)      ; Get MSB,EXP of old arg value
F15A E5                 PUSH    HL              ; Save it
F15B 21E010             LD      HL,FNARG        ; HL = Value of argument
F15E D5                 PUSH    DE              ; Save FN code string address
F15F CD6BF8             CALL    FPTHL           ; Move FPREG to argument
F162 E1                 POP     HL              ; Get FN code string address
F163 CD41ED             CALL    GETNUM          ; Get value from function
F166 2B                 DEC     HL              ; DEC 'cos GETCHR INCs
F167 CD36E8             CALL    GETCHR          ; Get next character
F16A C2ADE3             JP      NZ,SNERR        ; Bad character in FN - Error
F16D E1                 POP     HL              ; Get MSB,EXP of old arg
F16E 22E010             LD      (FNARG),HL      ; Restore it
F171 E1                 POP     HL              ; Get LSB,NLSB of old arg
F172 22E210             LD      (FNARG+2),HL    ; Restore it
F175 E1                 POP     HL              ; Get name of old arg
F176 22DE10             LD      (FNRGNM),HL     ; Restore it
F179 E1                 POP     HL              ; Restore code string address
F17A C9                 RET

F17B E5         IDTEST: PUSH    HL              ; Save code string address
F17C 2A5C10             LD      HL,(LINEAT)     ; Get current line number
F17F 23                 INC     HL              ; -1 means direct statement
F180 7C                 LD      A,H
F181 B5                 OR      L
F182 E1                 POP     HL              ; Restore code string address
F183 C0                 RET     NZ              ; Return if in program
F184 1E16               LD      E,ID            ; ?ID Error
F186 C3C1E3             JP      ERROR


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











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