mirror of
https://github.com/RevCurtisP/C02.git
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93 lines
2.8 KiB
Plaintext
93 lines
2.8 KiB
Plaintext
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;Apple 1 program initialization code for c02 programs
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;System Specific ASCII Key Mappings
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DELKEY EQU $08 ;Delete/Backspace Key (Left Arrow)
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ESCKEY EQU $1B ;Escape/Stop Key (Escape)
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RTNKEY EQU $0D ;Return/Enter Key (Return)
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;Standard Library Variables
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DSTLO EQU $06 ;Destination String Pointer (string.a02)
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DSTHI EQU $07
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BLKLO EQU $08 ;Block Segment Pointer (block.a02)
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BLKHI EQU $09
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PTRLO EQU $1D ;System Pointer (pointer.a02)
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PTRHI EQU $1E
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RANDOM EQU $1F ;Random Number
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RDSEED EQU $4E ;O/S Random Number Low Byte
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; EQU $4F ;O/S Random Number High Byte
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SRCLO EQU $71 ;Source String Pointer (stdio.a02)
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SRCHI EQU $72
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; $E3 ;Unused
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BLKSLO EQU $EB ;Block Start Address
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BLKSHI EQU $ED
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BLKELO EQU $ED ;Block End Address
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BLKEHI EQU $EE
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BLKLEN EQU $EF ;Block Segment Length
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TEMP0 EQU $FC ;Temporary Storage
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TEMP1 EQU $FD
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TEMP2 EQU $FE
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TEMP3 EQU $FF
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;I/O Locations
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KBD EQU $C000 ;Keyboard Data
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AKD EQU $C010 ;Keyboard Strobe Register
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;Monitor Routines
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RDKEY EQU $FD0C ;Waits for keypress and return in A
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KEYIN EQU $FD1B ;Waits for keypress and cycle random-number generator
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RDCHAR EQU $FD35 ;Read keyboard (processing escapes)
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GETLIN EQU $FD6A ;Get Line from Keyboard into Input Buffer
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CROUT EQU $FD8E ;Performs a carriage return
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PRBYTE EQU $FDDA ;Print Accumulator as Hexadecimal Number
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PRHEX EQU $FDE3 ;Print Low Nybble of Accumulator as Hex Digit
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COUT EQU $FDED ;Print Character in Accumulator
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BELL EQU $FF3A ;Ring Bell through COUT
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MONZ EQU $FF69 ;Enter monitor (<Control-C>, <Return> leaves the monitor)
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ECHO EQU COUT ;Print Character
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EXIT EQU MONZ ;Return to Monitor
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ORG $0C00 ;Safe Area for Machine Language
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START: JMP MAIN ;Execute Program
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;Subroutine Poll Keyboard
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PLKEY: LDA #0 ;Clear Accumulator
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BIT KBD ;Check Keyboard Strobe Bit
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BPL PLKEYR ;If Key Pressed
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LDA KBD ; Load Key Value
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STA AKD ; Clear Strobe
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PLKEYR: RTS
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;Read Keyboard
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GETKEY EQU KEYIN ;Alias to Monitor Routine
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PRCHR EQU ECHO ;Alias to Monitor Routine
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;Delete Previous Character
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DELCHR: LDX #2 ;Two Characters Total
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LDA #$88 ;Load Backspace Character
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JSR PRBLNX ;Print Accumulator and X-1 Blanks
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LDA #$88 ;Load Backspace Character
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JMP PRCHR ;and Print it
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;Advance Character to Next line
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NEWLIN EQU CROUT ;Alias to Monitor Routine
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;Initialize Destination String Pointer and Index
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SETDST: STX DSTLO ;Save Destination String Pointer
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STY DSTHI
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RTS
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;Initialize Source String Pointer and Index
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SETSRC: STX SRCLO ;Save Source String Pointer
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STY SRCHI
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LDY #$00 ;Initialize Index Into String
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RTS
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;Retrieve Source String Pointer
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GETSRC: LDX SRCLO
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LDY SRCHI
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RTS
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