mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-22 01:31:33 +00:00
98 lines
3.1 KiB
Plaintext
98 lines
3.1 KiB
Plaintext
;Apple 1 program initialization code for c02 programs
|
|
|
|
;System Specific ASCII Key Mappings
|
|
DELKEY EQU $5F ;Delete/Backspace Key (Left Arrow/Underscore)
|
|
ESCKEY EQU $1B ;Escape/Stop Key (Escape)
|
|
RTNKEY EQU $0D ;Return/Enter Key (Carriage Return)
|
|
|
|
;Locations used by Monitor
|
|
XAML EQU $24 ;Examine Index
|
|
XAMH EQU $25 ;
|
|
STL EQU $26 ;Store Index
|
|
STH EQU $27 ;
|
|
HEXL EQU $28 ;Hex Data
|
|
HEXH EQU $29 ;
|
|
YSAVE EQU $2A ;Y Register Storage
|
|
MODE EQU $2B ;Mode: Store, Examine, Block Examine
|
|
BUFFER EQU $200 ;Input Buffer
|
|
|
|
;Standard Library Variables
|
|
SRCLO EQU $30 ;Source String Pointer (stdio.a02)
|
|
SRCHI EQU $31
|
|
DSTLO EQU $32 ;Destination String Pointer (string.a02)
|
|
DSTHI EQU $33
|
|
DSTLO EQU $34 ;Destination String Pointer (string.a02)
|
|
DSTHI EQU $35
|
|
BLKLO EQU $36 ;Block Segment Pointer (block.a02)
|
|
BLKHI EQU $37
|
|
STKLO EQU $38 ;System Pointer (pointer.a02)
|
|
STKHI EQU $39
|
|
|
|
RDSEED EQU $3E ;Pseudo-RANDOM Seed
|
|
RANDOM EQU $3F ;Pseudo-RANDOM Number Storage
|
|
|
|
TEMP0 EQU $40 ;Temporary Storage
|
|
TEMP1 EQU $41
|
|
TEMP2 EQU $42
|
|
TEMP3 EQU $43
|
|
|
|
BLKLEN EQU $47 ;Block Segment Length
|
|
BLKSLO EQU $48 ;Block Start Address
|
|
BLKSHI EQU $49
|
|
BLKELO EQU $4A ;Block End Address
|
|
BLKEHI EQU $4B
|
|
STKSLO EQU $4C ;Stack Start Address
|
|
STKSHI EQU $4D
|
|
STKELO EQU $4E ;Stack End Address
|
|
STKEHI EQU $4F
|
|
|
|
;PIA 6820 Registers
|
|
KBD EQU $D010 ;Keyboard Data
|
|
KBDCR EQU $D011 ;Keyboard Control Register
|
|
DSP EQU $D012 ;Display Data
|
|
DSPCR EQU $D013 ;Display Control Register
|
|
|
|
EXIT EQU $FF00 ;Monitor Entry Point
|
|
ECHO EQU $FFEF ;Subroutine - Print Character in Accumulator
|
|
PRBYTE EQU $FFDC ;Subroutine - Print Accumulator as Hexadadecimal number
|
|
PRHEX EQU $FFE5 ;Subroutine - Print Low Nybble of Accumulator as Hex Digit
|
|
|
|
ORG $0300 ;Start one page above Monitor input buffer
|
|
|
|
START: LDX #$FF ;Reset stack - the monitor doesn't do this
|
|
TXS ; (probably because of lack of space)
|
|
JSR NEWLIN ;Move cursor to next line before executing program
|
|
JMP MAIN ;Execute Program
|
|
|
|
|
|
;Subroutine Poll Keyboard
|
|
PLKEY: INC RDSEED ;Cycle Keypress Counter
|
|
BIT KBDCR ;Check the Keyboard Control Register
|
|
BMI RDKEYA ;If Key Pressed, Read Key
|
|
LDA #0 ;Otherwise Return ASCII NUL
|
|
RTS
|
|
|
|
GETCHR: INC RDSEED ;Cycle Keypress Counter
|
|
RDKEYC: BIT KBDCR ;Check the Keyboard Control Register
|
|
BPL RDKEYC ; and loop if key not pressed
|
|
RDKEYA: LDA KBD ; Read key into Accumulator
|
|
RTS
|
|
|
|
GETKEY: JSR GETCHR ;Subroutine - Read ASCII from Keyboard
|
|
GETKEA: AND #$7F ;Strip High Bit
|
|
BIT GETKEM ;If Character is in
|
|
BEQ GETKEX ; Alpha Block ($40-$74)
|
|
AND #$5F ; Strip Bit 5
|
|
GETKEX: RTS
|
|
GETKEM: DC $40 ;Character Block Bit Mask
|
|
|
|
PUTCHR EQU ECHO ;Alias to Monitor Routine
|
|
|
|
;Delete Previous Character
|
|
DELCHR: LDA #DELKEY ;Load Underscore Character
|
|
JMP PUTCHR ; and Print it
|
|
|
|
;Advance Character to Next line
|
|
NEWLIN: LDA #$0D ;Load C/R into Accumulator
|
|
JMP PUTCHR ; and Print it
|