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bas32K.asm
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bas32K.asm
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;==================================================================================
; The updates to the original BASIC within this file are copyright Grant Searle
;
; You have permission to use this for NON COMMERCIAL USE ONLY
; If you wish to use it elsewhere, please include an acknowledgement to myself.
;
; http://searle.hostei.com/grant/index.html
;
; eMail: home.micros01@btinternet.com
;
; If the above don't work, please perform an Internet search to see if I have
; updated the web page hosting service.
;
;==================================================================================
; NASCOM ROM BASIC Ver 4.7, (C) 1978 Microsoft
; Scanned from source published in 80-BUS NEWS from Vol 2, Issue 3
; (May-June 1983) to Vol 3, Issue 3 (May-June 1984)
; Adapted for the freeware Zilog Macro Assembler 2.10 to produce
; the original ROM code (checksum A934H). PA
; GENERAL EQUATES
CTRLC .EQU 03H ; Control "C"
CTRLG .EQU 07H ; Control "G"
BKSP .EQU 08H ; Back space
LF .EQU 0AH ; Line feed
CS .EQU 0CH ; Clear screen
CR .EQU 0DH ; Carriage return
CTRLO .EQU 0FH ; Control "O"
CTRLQ .EQU 11H ; Control "Q"
CTRLR .EQU 12H ; Control "R"
CTRLS .EQU 13H ; Control "S"
CTRLU .EQU 15H ; Control "U"
ESC .EQU 1BH ; Escape
DEL .EQU 7FH ; Delete
; BASIC WORK SPACE LOCATIONS
WRKSPC .EQU 8045H ; BASIC Work space
USR .EQU WRKSPC+3H ; "USR (x)" jump
OUTSUB .EQU WRKSPC+6H ; "OUT p,n"
OTPORT .EQU WRKSPC+7H ; Port (p)
DIVSUP .EQU WRKSPC+9H ; Division support routine
DIV1 .EQU WRKSPC+0AH ; <- Values
DIV2 .EQU WRKSPC+0EH ; <- to
DIV3 .EQU WRKSPC+12H ; <- be
DIV4 .EQU WRKSPC+15H ; <-inserted
SEED .EQU WRKSPC+17H ; Random number seed
LSTRND .EQU WRKSPC+3AH ; Last random number
INPSUB .EQU WRKSPC+3EH ; #INP (x)" Routine
INPORT .EQU WRKSPC+3FH ; PORT (x)
NULLS .EQU WRKSPC+41H ; Number of nulls
LWIDTH .EQU WRKSPC+42H ; Terminal width
COMMAN .EQU WRKSPC+43H ; Width for commas
NULFLG .EQU WRKSPC+44H ; Null after input byte flag
CTLOFG .EQU WRKSPC+45H ; Control "O" flag
LINESC .EQU WRKSPC+46H ; Lines counter
LINESN .EQU WRKSPC+48H ; Lines number
CHKSUM .EQU WRKSPC+4AH ; Array load/save check sum
NMIFLG .EQU WRKSPC+4CH ; Flag for NMI break routine
BRKFLG .EQU WRKSPC+4DH ; Break flag
RINPUT .EQU WRKSPC+4EH ; Input reflection
POINT .EQU WRKSPC+51H ; "POINT" reflection (unused)
PSET .EQU WRKSPC+54H ; "SET" reflection
RESET .EQU WRKSPC+57H ; "RESET" reflection
STRSPC .EQU WRKSPC+5AH ; Bottom of string space
LINEAT .EQU WRKSPC+5CH ; Current line number
BASTXT .EQU WRKSPC+5EH ; Pointer to start of program
BUFFER .EQU WRKSPC+61H ; Input buffer
STACK .EQU WRKSPC+66H ; Initial stack
CURPOS .EQU WRKSPC+0ABH ; Character position on line
LCRFLG .EQU WRKSPC+0ACH ; Locate/Create flag
TYPE .EQU WRKSPC+0ADH ; Data type flag
DATFLG .EQU WRKSPC+0AEH ; Literal statement flag
LSTRAM .EQU WRKSPC+0AFH ; Last available RAM
TMSTPT .EQU WRKSPC+0B1H ; Temporary string pointer
TMSTPL .EQU WRKSPC+0B3H ; Temporary string pool
TMPSTR .EQU WRKSPC+0BFH ; Temporary string
STRBOT .EQU WRKSPC+0C3H ; Bottom of string space
CUROPR .EQU WRKSPC+0C5H ; Current operator in EVAL
LOOPST .EQU WRKSPC+0C7H ; First statement of loop
DATLIN .EQU WRKSPC+0C9H ; Line of current DATA item
FORFLG .EQU WRKSPC+0CBH ; "FOR" loop flag
LSTBIN .EQU WRKSPC+0CCH ; Last byte entered
READFG .EQU WRKSPC+0CDH ; Read/Input flag
BRKLIN .EQU WRKSPC+0CEH ; Line of break
NXTOPR .EQU WRKSPC+0D0H ; Next operator in EVAL
ERRLIN .EQU WRKSPC+0D2H ; Line of error
CONTAD .EQU WRKSPC+0D4H ; Where to CONTinue
PROGND .EQU WRKSPC+0D6H ; End of program
VAREND .EQU WRKSPC+0D8H ; End of variables
ARREND .EQU WRKSPC+0DAH ; End of arrays
NXTDAT .EQU WRKSPC+0DCH ; Next data item
FNRGNM .EQU WRKSPC+0DEH ; Name of FN argument
FNARG .EQU WRKSPC+0E0H ; FN argument value
FPREG .EQU WRKSPC+0E4H ; Floating point register
FPEXP .EQU FPREG+3 ; Floating point exponent
SGNRES .EQU WRKSPC+0E8H ; Sign of result
PBUFF .EQU WRKSPC+0E9H ; Number print buffer
MULVAL .EQU WRKSPC+0F6H ; Multiplier
PROGST .EQU WRKSPC+0F9H ; Start of program text area
STLOOK .EQU WRKSPC+15DH ; Start of memory test
; BASIC ERROR CODE VALUES
NF .EQU 00H ; NEXT without FOR
SN .EQU 02H ; Syntax error
RG .EQU 04H ; RETURN without GOSUB
OD .EQU 06H ; Out of DATA
FC .EQU 08H ; Function call error
OV .EQU 0AH ; Overflow
OM .EQU 0CH ; Out of memory
UL .EQU 0EH ; Undefined line number
BS .EQU 10H ; Bad subscript
DD .EQU 12H ; Re-DIMensioned array
DZ .EQU 14H ; Division by zero (/0)
ID .EQU 16H ; Illegal direct
TM .EQU 18H ; Type miss-match
OS .EQU 1AH ; Out of string space
LS .EQU 1CH ; String too long
ST .EQU 1EH ; String formula too complex
CN .EQU 20H ; Can't CONTinue
UF .EQU 22H ; UnDEFined FN function
MO .EQU 24H ; Missing operand
HX .EQU 26H ; HEX error
BN .EQU 28H ; BIN error
.ORG 0100H
COLD: JP STARTB ; Jump for cold start
WARM: JP WARMST ; Jump for warm start
STARTB:
LD IX,0 ; Flag cold start
JP CSTART ; Jump to initialise
.WORD DEINT ; Get integer -32768 to 32767
.WORD ABPASS ; Return integer in AB
CSTART: LD HL,WRKSPC ; Start of workspace RAM
LD SP,HL ; Set up a temporary stack
JP INITST ; Go to initialise
INIT: LD DE,INITAB ; Initialise workspace
LD B,INITBE-INITAB+3; Bytes to copy
LD HL,WRKSPC ; Into workspace RAM
COPY: LD A,(DE) ; Get source
LD (HL),A ; To destination
INC HL ; Next destination
INC DE ; Next source
DEC B ; Count bytes
JP NZ,COPY ; More to move
LD SP,HL ; Temporary stack
CALL CLREG ; Clear registers and stack
CALL PRNTCRLF ; Output CRLF
LD (BUFFER+72+1),A ; Mark end of buffer
LD (PROGST),A ; Initialise program area
MSIZE: LD HL,MEMMSG ; Point to message
CALL PRS ; Output "Memory size"
CALL PROMPT ; Get input with '?'
CALL GETCHR ; Get next character
OR A ; Set flags
JP NZ,TSTMEM ; If number - Test if RAM there
LD HL,STLOOK ; Point to start of RAM
MLOOP: INC HL ; Next byte
LD A,H ; Above address FFFF ?
OR L
JP Z,SETTOP ; Yes - 64K RAM
LD A,(HL) ; Get contents
LD B,A ; Save it
CPL ; Flip all bits
LD (HL),A ; Put it back
CP (HL) ; RAM there if same
LD (HL),B ; Restore old contents
JP Z,MLOOP ; If RAM - test next byte
JP SETTOP ; Top of RAM found
TSTMEM: CALL ATOH ; Get high memory into DE
OR A ; Set flags on last byte
JP NZ,SNERR ; ?SN Error if bad character
EX DE,HL ; Address into HL
DEC HL ; Back one byte
LD A,11011001B ; Test byte
LD B,(HL) ; Get old contents
LD (HL),A ; Load test byte
CP (HL) ; RAM there if same
LD (HL),B ; Restore old contents
JP NZ,MSIZE ; Ask again if no RAM
SETTOP: DEC HL ; Back one byte
LD DE,STLOOK-1 ; See if enough RAM
CALL CPDEHL ; Compare DE with HL
JP C,MSIZE ; Ask again if not enough RAM
LD DE,0-50 ; 50 Bytes string space
LD (LSTRAM),HL ; Save last available RAM
ADD HL,DE ; Allocate string space
LD (STRSPC),HL ; Save string space
CALL CLRPTR ; Clear program area
LD HL,(STRSPC) ; Get end of memory
LD DE,0-17 ; Offset for free bytes
ADD HL,DE ; Adjust HL
LD DE,PROGST ; Start of program text
LD A,L ; Get LSB
SUB E ; Adjust it
LD L,A ; Re-save
LD A,H ; Get MSB
SBC A,D ; Adjust it
LD H,A ; Re-save
PUSH HL ; Save bytes free
LD HL,SIGNON ; Sign-on message
CALL PRS ; Output string
POP HL ; Get bytes free back
CALL PRNTHL ; Output amount of free memory
LD HL,BFREE ; " Bytes free" message
CALL PRS ; Output string
WARMST: LD SP,STACK ; Temporary stack
BRKRET: CALL CLREG ; Clear registers and stack
JP PRNTOK ; Go to get command line
BFREE: .BYTE " Bytes free",CR,LF,0,0
SIGNON: .BYTE "Z80 BASIC Ver 4.7b",CR,LF
.BYTE "Copyright ",40,"C",41
.BYTE " 1978 by Microsoft",CR,LF,0,0
MEMMSG: .BYTE "Memory top",0
; FUNCTION ADDRESS TABLE
FNCTAB: .WORD SGN
.WORD INT
.WORD ABS
.WORD USR
.WORD FRE
.WORD INP
.WORD POS
.WORD SQR
.WORD RND
.WORD LOG
.WORD EXP
.WORD COS
.WORD SIN
.WORD TAN
.WORD ATN
.WORD PEEK
.WORD DEEK
.WORD POINT
.WORD LEN
.WORD STR
.WORD VAL
.WORD ASC
.WORD CHR
.WORD HEX
.WORD BIN
.WORD LEFT
.WORD RIGHT
.WORD MID
; RESERVED WORD LIST
WORDS: .BYTE 'E'+80H,"ND"
.BYTE 'F'+80H,"OR"
.BYTE 'N'+80H,"EXT"
.BYTE 'D'+80H,"ATA"
.BYTE 'I'+80H,"NPUT"
.BYTE 'D'+80H,"IM"
.BYTE 'R'+80H,"EAD"
.BYTE 'L'+80H,"ET"
.BYTE 'G'+80H,"OTO"
.BYTE 'R'+80H,"UN"
.BYTE 'I'+80H,"F"
.BYTE 'R'+80H,"ESTORE"
.BYTE 'G'+80H,"OSUB"
.BYTE 'R'+80H,"ETURN"
.BYTE 'R'+80H,"EM"
.BYTE 'S'+80H,"TOP"
.BYTE 'O'+80H,"UT"
.BYTE 'O'+80H,"N"
.BYTE 'N'+80H,"ULL"
.BYTE 'W'+80H,"AIT"
.BYTE 'D'+80H,"EF"
.BYTE 'P'+80H,"OKE"
.BYTE 'D'+80H,"OKE"
.BYTE 'S'+80H,"CREEN"
.BYTE 'L'+80H,"INES"
.BYTE 'C'+80H,"LS"
.BYTE 'W'+80H,"IDTH"
.BYTE 'M'+80H,"ONITOR"
.BYTE 'S'+80H,"ET"
.BYTE 'R'+80H,"ESET"
.BYTE 'P'+80H,"RINT"
.BYTE 'C'+80H,"ONT"
.BYTE 'L'+80H,"IST"
.BYTE 'C'+80H,"LEAR"
.BYTE 'C'+80H,"LOAD"
.BYTE 'C'+80H,"SAVE"
.BYTE 'N'+80H,"EW"
.BYTE 'T'+80H,"AB("
.BYTE 'T'+80H,"O"
.BYTE 'F'+80H,"N"
.BYTE 'S'+80H,"PC("
.BYTE 'T'+80H,"HEN"
.BYTE 'N'+80H,"OT"
.BYTE 'S'+80H,"TEP"
.BYTE '+'+80H
.BYTE '-'+80H
.BYTE '*'+80H
.BYTE '/'+80H
.BYTE '^'+80H
.BYTE 'A'+80H,"ND"
.BYTE 'O'+80H,"R"
.BYTE '>'+80H
.BYTE '='+80H
.BYTE '<'+80H
.BYTE 'S'+80H,"GN"
.BYTE 'I'+80H,"NT"
.BYTE 'A'+80H,"BS"
.BYTE 'U'+80H,"SR"
.BYTE 'F'+80H,"RE"
.BYTE 'I'+80H,"NP"
.BYTE 'P'+80H,"OS"
.BYTE 'S'+80H,"QR"
.BYTE 'R'+80H,"ND"
.BYTE 'L'+80H,"OG"
.BYTE 'E'+80H,"XP"
.BYTE 'C'+80H,"OS"
.BYTE 'S'+80H,"IN"
.BYTE 'T'+80H,"AN"
.BYTE 'A'+80H,"TN"
.BYTE 'P'+80H,"EEK"
.BYTE 'D'+80H,"EEK"
.BYTE 'P'+80H,"OINT"
.BYTE 'L'+80H,"EN"
.BYTE 'S'+80H,"TR$"
.BYTE 'V'+80H,"AL"
.BYTE 'A'+80H,"SC"
.BYTE 'C'+80H,"HR$"
.BYTE 'H'+80H,"EX$"
.BYTE 'B'+80H,"IN$"
.BYTE 'L'+80H,"EFT$"
.BYTE 'R'+80H,"IGHT$"
.BYTE 'M'+80H,"ID$"
.BYTE 80H ; End of list marker
; KEYWORD ADDRESS TABLE
WORDTB: .WORD PEND
.WORD FOR
.WORD NEXT
.WORD DATA
.WORD INPUT
.WORD DIM
.WORD READ
.WORD LET
.WORD GOTO
.WORD RUN
.WORD IF
.WORD RESTOR
.WORD GOSUB
.WORD RETURN
.WORD REM
.WORD STOP
.WORD POUT
.WORD ON
.WORD NULL
.WORD WAIT
.WORD DEF
.WORD POKE
.WORD DOKE
.WORD REM
.WORD LINES
.WORD CLS
.WORD WIDTH
.WORD MONITR
.WORD PSET
.WORD RESET
.WORD PRINT
.WORD CONT
.WORD LIST
.WORD CLEAR
.WORD REM
.WORD REM
.WORD NEW
; RESERVED WORD TOKEN VALUES
ZEND .EQU 080H ; END
ZFOR .EQU 081H ; FOR
ZDATA .EQU 083H ; DATA
ZGOTO .EQU 088H ; GOTO
ZGOSUB .EQU 08CH ; GOSUB
ZREM .EQU 08EH ; REM
ZPRINT .EQU 09EH ; PRINT
ZNEW .EQU 0A4H ; NEW
ZTAB .EQU 0A5H ; TAB
ZTO .EQU 0A6H ; TO
ZFN .EQU 0A7H ; FN
ZSPC .EQU 0A8H ; SPC
ZTHEN .EQU 0A9H ; THEN
ZNOT .EQU 0AAH ; NOT
ZSTEP .EQU 0ABH ; STEP
ZPLUS .EQU 0ACH ; +
ZMINUS .EQU 0ADH ; -
ZTIMES .EQU 0AEH ; *
ZDIV .EQU 0AFH ; /
ZOR .EQU 0B2H ; OR
ZGTR .EQU 0B3H ; >
ZEQUAL .EQU 0B4H ; M
ZLTH .EQU 0B5H ; <
ZSGN .EQU 0B6H ; SGN
ZPOINT .EQU 0C7H ; POINT
ZLEFT .EQU 0CDH +2 ; LEFT$
; ARITHMETIC PRECEDENCE TABLE
PRITAB: .BYTE 79H ; Precedence value
.WORD PADD ; FPREG = <last> + FPREG
.BYTE 79H ; Precedence value
.WORD PSUB ; FPREG = <last> - FPREG
.BYTE 7CH ; Precedence value
.WORD MULT ; PPREG = <last> * FPREG
.BYTE 7CH ; Precedence value
.WORD DIV ; FPREG = <last> / FPREG
.BYTE 7FH ; Precedence value
.WORD POWER ; FPREG = <last> ^ FPREG
.BYTE 50H ; Precedence value
.WORD PAND ; FPREG = <last> AND FPREG
.BYTE 46H ; Precedence value
.WORD POR ; FPREG = <last> OR FPREG
; BASIC ERROR CODE LIST
ERRORS: .BYTE "NF" ; NEXT without FOR
.BYTE "SN" ; Syntax error
.BYTE "RG" ; RETURN without GOSUB
.BYTE "OD" ; Out of DATA
.BYTE "FC" ; Illegal function call
.BYTE "OV" ; Overflow error
.BYTE "OM" ; Out of memory
.BYTE "UL" ; Undefined line
.BYTE "BS" ; Bad subscript
.BYTE "DD" ; Re-DIMensioned array
.BYTE "/0" ; Division by zero
.BYTE "ID" ; Illegal direct
.BYTE "TM" ; Type mis-match
.BYTE "OS" ; Out of string space
.BYTE "LS" ; String too long
.BYTE "ST" ; String formula too complex
.BYTE "CN" ; Can't CONTinue
.BYTE "UF" ; Undefined FN function
.BYTE "MO" ; Missing operand
.BYTE "HX" ; HEX error
.BYTE "BN" ; BIN error
; INITIALISATION TABLE -------------------------------------------------------
INITAB: JP WARMST ; Warm start jump
JP FCERR ; "USR (X)" jump (Set to Error)
OUT (0),A ; "OUT p,n" skeleton
RET
SUB 0 ; Division support routine
LD L,A
LD A,H
SBC A,0
LD H,A
LD A,B
SBC A,0
LD B,A
LD A,0
RET
.BYTE 0,0,0 ; Random number seed table used by RND
.BYTE 035H,04AH,0CAH,099H ;-2.65145E+07
.BYTE 039H,01CH,076H,098H ; 1.61291E+07
.BYTE 022H,095H,0B3H,098H ;-1.17691E+07
.BYTE 00AH,0DDH,047H,098H ; 1.30983E+07
.BYTE 053H,0D1H,099H,099H ;-2-01612E+07
.BYTE 00AH,01AH,09FH,098H ;-1.04269E+07
.BYTE 065H,0BCH,0CDH,098H ;-1.34831E+07
.BYTE 0D6H,077H,03EH,098H ; 1.24825E+07
.BYTE 052H,0C7H,04FH,080H ; Last random number
IN A,(0) ; INP (x) skeleton
RET
.BYTE 1 ; POS (x) number (1)
.BYTE 255 ; Terminal width (255 = no auto CRLF)
.BYTE 28 ; Width for commas (3 columns)
.BYTE 0 ; No nulls after input bytes
.BYTE 0 ; Output enabled (^O off)
.WORD 20 ; Initial lines counter
.WORD 20 ; Initial lines number
.WORD 0 ; Array load/save check sum
.BYTE 0 ; Break not by NMI
.BYTE 0 ; Break flag
JP TTYLIN ; Input reflection (set to TTY)
JP $0000 ; POINT reflection unused
JP $0000 ; SET reflection
JP $0000 ; RESET reflection
.WORD STLOOK ; Temp string space
.WORD -2 ; Current line number (cold)
.WORD PROGST+1 ; Start of program text
INITBE:
; END OF INITIALISATION TABLE ---------------------------------------------------
ERRMSG: .BYTE " Error",0
INMSG: .BYTE " in ",0
ZERBYT .EQU $-1 ; A zero byte
OKMSG: .BYTE "Ok",CR,LF,0,0
BRKMSG: .BYTE "Break",0
BAKSTK: LD HL,4 ; Look for "FOR" block with
ADD HL,SP ; same index as specified
LOKFOR: LD A,(HL) ; Get block ID
INC HL ; Point to index address
CP ZFOR ; Is it a "FOR" token
RET NZ ; No - exit
LD C,(HL) ; BC = Address of "FOR" index
INC HL
LD B,(HL)
INC HL ; Point to sign of STEP
PUSH HL ; Save pointer to sign
LD L,C ; HL = address of "FOR" index
LD H,B
LD A,D ; See if an index was specified
OR E ; DE = 0 if no index specified
EX DE,HL ; Specified index into HL
JP Z,INDFND ; Skip if no index given
EX DE,HL ; Index back into DE
CALL CPDEHL ; Compare index with one given
INDFND: LD BC,16-3 ; Offset to next block
POP HL ; Restore pointer to sign
RET Z ; Return if block found
ADD HL,BC ; Point to next block
JP LOKFOR ; Keep on looking
MOVUP: CALL ENFMEM ; See if enough memory
MOVSTR: PUSH BC ; Save end of source
EX (SP),HL ; Swap source and dest" end
POP BC ; Get end of destination
MOVLP: CALL CPDEHL ; See if list moved
LD A,(HL) ; Get byte
LD (BC),A ; Move it
RET Z ; Exit if all done
DEC BC ; Next byte to move to
DEC HL ; Next byte to move
JP MOVLP ; Loop until all bytes moved
CHKSTK: PUSH HL ; Save code string address
LD HL,(ARREND) ; Lowest free memory
LD B,0 ; BC = Number of levels to test
ADD HL,BC ; 2 Bytes for each level
ADD HL,BC
.BYTE 3EH ; Skip "PUSH HL"
ENFMEM: PUSH HL ; Save code string address
LD A,0D0H ;LOW -48 ; 48 Bytes minimum RAM
SUB L
LD L,A
LD A,0FFH; HIGH (-48) ; 48 Bytes minimum RAM
SBC A,H
JP C,OMERR ; Not enough - ?OM Error
LD H,A
ADD HL,SP ; Test if stack is overflowed
POP HL ; Restore code string address
RET C ; Return if enough mmory
OMERR: LD E,OM ; ?OM Error
JP ERROR
DATSNR: LD HL,(DATLIN) ; Get line of current DATA item
LD (LINEAT),HL ; Save as current line
SNERR: LD E,SN ; ?SN Error
.BYTE 01H ; Skip "LD E,DZ"
DZERR: LD E,DZ ; ?/0 Error
.BYTE 01H ; Skip "LD E,NF"
NFERR: LD E,NF ; ?NF Error
.BYTE 01H ; Skip "LD E,DD"
DDERR: LD E,DD ; ?DD Error
.BYTE 01H ; Skip "LD E,UF"
UFERR: LD E,UF ; ?UF Error
.BYTE 01H ; Skip "LD E,OV
OVERR: LD E,OV ; ?OV Error
.BYTE 01H ; Skip "LD E,TM"
TMERR: LD E,TM ; ?TM Error
ERROR: CALL CLREG ; Clear registers and stack
LD (CTLOFG),A ; Enable output (A is 0)
CALL STTLIN ; Start new line
LD HL,ERRORS ; Point to error codes
LD D,A ; D = 0 (A is 0)
LD A,'?'
CALL OUTC ; Output '?'
ADD HL,DE ; Offset to correct error code
LD A,(HL) ; First character
CALL OUTC ; Output it
CALL GETCHR ; Get next character
CALL OUTC ; Output it
LD HL,ERRMSG ; "Error" message
ERRIN: CALL PRS ; Output message
LD HL,(LINEAT) ; Get line of error
LD DE,-2 ; Cold start error if -2
CALL CPDEHL ; See if cold start error
JP Z,CSTART ; Cold start error - Restart
LD A,H ; Was it a direct error?
AND L ; Line = -1 if direct error
INC A
CALL NZ,LINEIN ; No - output line of error
.BYTE 3EH ; Skip "POP BC"
POPNOK: POP BC ; Drop address in input buffer
PRNTOK: XOR A ; Output "Ok" and get command
LD (CTLOFG),A ; Enable output
CALL STTLIN ; Start new line
LD HL,OKMSG ; "Ok" message
CALL PRS ; Output "Ok"
GETCMD: LD HL,-1 ; Flag direct mode
LD (LINEAT),HL ; Save as current line
CALL GETLIN ; Get an input line
JP C,GETCMD ; Get line again if break
CALL GETCHR ; Get first character
INC A ; Test if end of line
DEC A ; Without affecting Carry
JP Z,GETCMD ; Nothing entered - Get another
PUSH AF ; Save Carry status
CALL ATOH ; Get line number into DE
PUSH DE ; Save line number
CALL CRUNCH ; Tokenise rest of line
LD B,A ; Length of tokenised line
POP DE ; Restore line number
POP AF ; Restore Carry
JP NC,EXCUTE ; No line number - Direct mode
PUSH DE ; Save line number
PUSH BC ; Save length of tokenised line
XOR A
LD (LSTBIN),A ; Clear last byte input
CALL GETCHR ; Get next character
OR A ; Set flags
PUSH AF ; And save them
CALL SRCHLN ; Search for line number in DE
JP C,LINFND ; Jump if line found
POP AF ; Get status
PUSH AF ; And re-save
JP Z,ULERR ; Nothing after number - Error
OR A ; Clear Carry
LINFND: PUSH BC ; Save address of line in prog
JP NC,INEWLN ; Line not found - Insert new
EX DE,HL ; Next line address in DE
LD HL,(PROGND) ; End of program
SFTPRG: LD A,(DE) ; Shift rest of program down
LD (BC),A
INC BC ; Next destination
INC DE ; Next source
CALL CPDEHL ; All done?
JP NZ,SFTPRG ; More to do
LD H,B ; HL - New end of program
LD L,C
LD (PROGND),HL ; Update end of program
INEWLN: POP DE ; Get address of line,
POP AF ; Get status
JP Z,SETPTR ; No text - Set up pointers
LD HL,(PROGND) ; Get end of program
EX (SP),HL ; Get length of input line
POP BC ; End of program to BC
ADD HL,BC ; Find new end
PUSH HL ; Save new end
CALL MOVUP ; Make space for line
POP HL ; Restore new end
LD (PROGND),HL ; Update end of program pointer
EX DE,HL ; Get line to move up in HL
LD (HL),H ; Save MSB
POP DE ; Get new line number
INC HL ; Skip pointer
INC HL
LD (HL),E ; Save LSB of line number
INC HL
LD (HL),D ; Save MSB of line number
INC HL ; To first byte in line
LD DE,BUFFER ; Copy buffer to program
MOVBUF: LD A,(DE) ; Get source
LD (HL),A ; Save destinations
INC HL ; Next source
INC DE ; Next destination
OR A ; Done?
JP NZ,MOVBUF ; No - Repeat
SETPTR: CALL RUNFST ; Set line pointers
INC HL ; To LSB of pointer
EX DE,HL ; Address to DE
PTRLP: LD H,D ; Address to HL
LD L,E
LD A,(HL) ; Get LSB of pointer
INC HL ; To MSB of pointer
OR (HL) ; Compare with MSB pointer
JP Z,GETCMD ; Get command line if end
INC HL ; To LSB of line number
INC HL ; Skip line number
INC HL ; Point to first byte in line
XOR A ; Looking for 00 byte
FNDEND: CP (HL) ; Found end of line?
INC HL ; Move to next byte
JP NZ,FNDEND ; No - Keep looking
EX DE,HL ; Next line address to HL
LD (HL),E ; Save LSB of pointer
INC HL
LD (HL),D ; Save MSB of pointer
JP PTRLP ; Do next line
SRCHLN: LD HL,(BASTXT) ; Start of program text
SRCHLP: LD B,H ; BC = Address to look at
LD C,L
LD A,(HL) ; Get address of next line
INC HL
OR (HL) ; End of program found?
DEC HL
RET Z ; Yes - Line not found
INC HL
INC HL
LD A,(HL) ; Get LSB of line number
INC HL
LD H,(HL) ; Get MSB of line number
LD L,A
CALL CPDEHL ; Compare with line in DE
LD H,B ; HL = Start of this line
LD L,C
LD A,(HL) ; Get LSB of next line address
INC HL
LD H,(HL) ; Get MSB of next line address
LD L,A ; Next line to HL
CCF
RET Z ; Lines found - Exit
CCF
RET NC ; Line not found,at line after
JP SRCHLP ; Keep looking
NEW: RET NZ ; Return if any more on line
CLRPTR: LD HL,(BASTXT) ; Point to start of program
XOR A ; Set program area to empty
LD (HL),A ; Save LSB = 00
INC HL
LD (HL),A ; Save MSB = 00
INC HL
LD (PROGND),HL ; Set program end
RUNFST: LD HL,(BASTXT) ; Clear all variables
DEC HL
INTVAR: LD (BRKLIN),HL ; Initialise RUN variables
LD HL,(LSTRAM) ; Get end of RAM
LD (STRBOT),HL ; Clear string space
XOR A
CALL RESTOR ; Reset DATA pointers
LD HL,(PROGND) ; Get end of program
LD (VAREND),HL ; Clear variables
LD (ARREND),HL ; Clear arrays
CLREG: POP BC ; Save return address
LD HL,(STRSPC) ; Get end of working RAN
LD SP,HL ; Set stack
LD HL,TMSTPL ; Temporary string pool
LD (TMSTPT),HL ; Reset temporary string ptr
XOR A ; A = 00
LD L,A ; HL = 0000
LD H,A
LD (CONTAD),HL ; No CONTinue
LD (FORFLG),A ; Clear FOR flag
LD (FNRGNM),HL ; Clear FN argument
PUSH HL ; HL = 0000
PUSH BC ; Put back return
DOAGN: LD HL,(BRKLIN) ; Get address of code to RUN
RET ; Return to execution driver
PROMPT: LD A,'?' ; '?'
CALL OUTC ; Output character
LD A,' ' ; Space
CALL OUTC ; Output character
JP RINPUT ; Get input line
CRUNCH: XOR A ; Tokenise line @ HL to BUFFER
LD (DATFLG),A ; Reset literal flag
LD C,2+3 ; 2 byte number and 3 nulls
LD DE,BUFFER ; Start of input buffer
CRNCLP: LD A,(HL) ; Get byte
CP ' ' ; Is it a space?
JP Z,MOVDIR ; Yes - Copy direct
LD B,A ; Save character
CP '"' ; Is it a quote?
JP Z,CPYLIT ; Yes - Copy literal string
OR A ; Is it end of buffer?
JP Z,ENDBUF ; Yes - End buffer
LD A,(DATFLG) ; Get data type
OR A ; Literal?
LD A,(HL) ; Get byte to copy
JP NZ,MOVDIR ; Literal - Copy direct
CP '?' ; Is it '?' short for PRINT
LD A,ZPRINT ; "PRINT" token
JP Z,MOVDIR ; Yes - replace it
LD A,(HL) ; Get byte again
CP '0' ; Is it less than '0'
JP C,FNDWRD ; Yes - Look for reserved words
CP 60; ";"+1 ; Is it "0123456789:;" ?
JP C,MOVDIR ; Yes - copy it direct
FNDWRD: PUSH DE ; Look for reserved words
LD DE,WORDS-1 ; Point to table
PUSH BC ; Save count
LD BC,RETNAD ; Where to return to
PUSH BC ; Save return address
LD B,ZEND-1 ; First token value -1
LD A,(HL) ; Get byte
CP 'a' ; Less than 'a' ?
JP C,SEARCH ; Yes - search for words
CP 'z'+1 ; Greater than 'z' ?
JP NC,SEARCH ; Yes - search for words
AND 01011111B ; Force upper case
LD (HL),A ; Replace byte
SEARCH: LD C,(HL) ; Search for a word
EX DE,HL
GETNXT: INC HL ; Get next reserved word
OR (HL) ; Start of word?
JP P,GETNXT ; No - move on
INC B ; Increment token value
LD A, (HL) ; Get byte from table
AND 01111111B ; Strip bit 7
RET Z ; Return if end of list
CP C ; Same character as in buffer?
JP NZ,GETNXT ; No - get next word
EX DE,HL
PUSH HL ; Save start of word
NXTBYT: INC DE ; Look through rest of word
LD A,(DE) ; Get byte from table
OR A ; End of word ?
JP M,MATCH ; Yes - Match found
LD C,A ; Save it
LD A,B ; Get token value
CP ZGOTO ; Is it "GOTO" token ?
JP NZ,NOSPC ; No - Don't allow spaces
CALL GETCHR ; Get next character
DEC HL ; Cancel increment from GETCHR
NOSPC: INC HL ; Next byte
LD A,(HL) ; Get byte
CP 'a' ; Less than 'a' ?
JP C,NOCHNG ; Yes - don't change
AND 01011111B ; Make upper case
NOCHNG: CP C ; Same as in buffer ?
JP Z,NXTBYT ; Yes - keep testing
POP HL ; Get back start of word
JP SEARCH ; Look at next word
MATCH: LD C,B ; Word found - Save token value
POP AF ; Throw away return
EX DE,HL
RET ; Return to "RETNAD"
RETNAD: EX DE,HL ; Get address in string
LD A,C ; Get token value
POP BC ; Restore buffer length
POP DE ; Get destination address
MOVDIR: INC HL ; Next source in buffer
LD (DE),A ; Put byte in buffer
INC DE ; Move up buffer
INC C ; Increment length of buffer
SUB ':' ; End of statement?
JP Z,SETLIT ; Jump if multi-statement line
CP ZDATA-3AH ; Is it DATA statement ?
JP NZ,TSTREM ; No - see if REM
SETLIT: LD (DATFLG),A ; Set literal flag
TSTREM: SUB ZREM-3AH ; Is it REM?
JP NZ,CRNCLP ; No - Leave flag
LD B,A ; Copy rest of buffer
NXTCHR: LD A,(HL) ; Get byte
OR A ; End of line ?
JP Z,ENDBUF ; Yes - Terminate buffer
CP B ; End of statement ?
JP Z,MOVDIR ; Yes - Get next one
CPYLIT: INC HL ; Move up source string
LD (DE),A ; Save in destination
INC C ; Increment length
INC DE ; Move up destination
JP NXTCHR ; Repeat
ENDBUF: LD HL,BUFFER-1 ; Point to start of buffer
LD (DE),A ; Mark end of buffer (A = 00)
INC DE
LD (DE),A ; A = 00
INC DE
LD (DE),A ; A = 00
RET
DODEL: LD A,(NULFLG) ; Get null flag status
OR A ; Is it zero?
LD A,0 ; Zero A - Leave flags
LD (NULFLG),A ; Zero null flag
JP NZ,ECHDEL ; Set - Echo it
DEC B ; Decrement length
JP Z,GETLIN ; Get line again if empty
CALL OUTC ; Output null character
.BYTE 3EH ; Skip "DEC B"
ECHDEL: DEC B ; Count bytes in buffer
DEC HL ; Back space buffer
JP Z,OTKLN ; No buffer - Try again
LD A,(HL) ; Get deleted byte
CALL OUTC ; Echo it
JP MORINP ; Get more input
DELCHR: DEC B ; Count bytes in buffer
DEC HL ; Back space buffer
CALL OUTC ; Output character in A
JP NZ,MORINP ; Not end - Get more
OTKLN: CALL OUTC ; Output character in A
KILIN: CALL PRNTCRLF ; Output CRLF
JP TTYLIN ; Get line again
GETLIN:
TTYLIN: LD HL,BUFFER ; Get a line by character
LD B,1 ; Set buffer as empty
XOR A
LD (NULFLG),A ; Clear null flag
MORINP: CALL CLOTST ; Get character and test ^O
LD C,A ; Save character in C
CP DEL ; Delete character?
JP Z,DODEL ; Yes - Process it
LD A,(NULFLG) ; Get null flag
OR A ; Test null flag status
JP Z,PROCES ; Reset - Process character
LD A,0 ; Set a null
CALL OUTC ; Output null
XOR A ; Clear A
LD (NULFLG),A ; Reset null flag
PROCES: LD A,C ; Get character
CP CTRLG ; Bell?
JP Z,PUTCTL ; Yes - Save it
CP CTRLC ; Is it control "C"?
CALL Z,PRNTCRLF ; Yes - Output CRLF
SCF ; Flag break
RET Z ; Return if control "C"
CP CR ; Is it enter?
JP Z,ENDINP ; Yes - Terminate input
CP CTRLU ; Is it control "U"?
JP Z,KILIN ; Yes - Get another line
CP '@' ; Is it "kill line"?
JP Z,OTKLN ; Yes - Kill line
CP '_' ; Is it delete?
JP Z,DELCHR ; Yes - Delete character
CP BKSP ; Is it backspace?
JP Z,DELCHR ; Yes - Delete character
CP CTRLR ; Is it control "R"?
JP NZ,PUTBUF ; No - Put in buffer
PUSH BC ; Save buffer length
PUSH DE ; Save DE
PUSH HL ; Save buffer address
LD (HL),0 ; Mark end of buffer
CALL OUTNCR ; Output and do CRLF
LD HL,BUFFER ; Point to buffer start
CALL PRS ; Output buffer
POP HL ; Restore buffer address
POP DE ; Restore DE
POP BC ; Restore buffer length
JP MORINP ; Get another character
PUTBUF: CP ' ' ; Is it a control code?
JP C,MORINP ; Yes - Ignore
PUTCTL: LD A,B ; Get number of bytes in buffer
CP 72+1 ; Test for line overflow
LD A,CTRLG ; Set a bell
JP NC,OUTNBS ; Ring bell if buffer full
LD A,C ; Get character
LD (HL),C ; Save in buffer
LD (LSTBIN),A ; Save last input byte
INC HL ; Move up buffer
INC B ; Increment length
OUTIT: CALL OUTC ; Output the character entered
JP MORINP ; Get another character
OUTNBS: CALL OUTC ; Output bell and back over it
LD A,BKSP ; Set back space
JP OUTIT ; Output it and get more
CPDEHL: LD A,H ; Get H
SUB D ; Compare with D
RET NZ ; Different - Exit
LD A,L ; Get L
SUB E ; Compare with E
RET ; Return status
CHKSYN: LD A,(HL) ; Check syntax of character
EX (SP),HL ; Address of test byte
CP (HL) ; Same as in code string?
INC HL ; Return address
EX (SP),HL ; Put it back
JP Z,GETCHR ; Yes - Get next character
JP SNERR ; Different - ?SN Error