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https://github.com/sehugg/8bitworkshop.git
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116 lines
3.6 KiB
Plaintext
116 lines
3.6 KiB
Plaintext
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; Atari 5200 "Hello World" sample code
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; Written by Daniel Boris (dboris@comcast.net)
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;
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; Assemble with DASM
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;
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processor 6502
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DMACTL equ $D400 ;DMA Control
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sDMACTL equ $07 ;DMA Control Shadow
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DLISTL equ $D402 ;Display list lo
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DLISTH equ $D403 ;Display list hi
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sDLISTL equ $05 ;Display list lo shadow
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sDLISTH equ $06 ;Display list hi shadow
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CHBASE equ $D409 ;Character set base
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CHACTL equ $D401 ;Character control
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NMIEN equ $D40E ;NMI Enable
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COLOR1 equ $0D ;Color 1 shadow
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COLOR2 equ $0E ;Color 2 shadow
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org $4000 ;Start of cartridge area
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sei ;Disable interrupts
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cld ;Clear decimal mode
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Start
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ldx #$00
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lda #$00
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crloop1
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sta $00,x ;Clear zero page
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sta $D400,x ;Clear ANTIC
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sta $C000,x ;Clear GTIA
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sta $E800,x ;Clear POKEY
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dex
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bne crloop1
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ldy #$00 ;Clear Ram
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lda #$02 ;Start at $0200
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sta $81
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lda #$00
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sta $80
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crloop2
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lda #$00
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crloop3
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sta ($80),y ;Store data
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iny ;Next byte
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bne crloop3 ;Branch if not done page
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inc $81 ;Next page
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lda $81
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cmp #$40 ;Check if end of RAM
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bne crloop2 ;Branch if not
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ldx #$21
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dlloop ;Create Display List
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lda dlist,x ;Get byte
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sta $1000,x ;Copy to RAM
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dex ;next byte
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bpl dlloop
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lda #$03 ;point IRQ vector
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sta $200 ;to BIOS routine
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lda #$FC
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sta $201
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lda #$B8 ;point VBI vector
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sta $202 ;to BIOS routine
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lda #$FC
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sta $203
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lda #$B2 ;point Deferred VBI
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sta $204 ;to BIOS routine
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lda #$FC
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sta $205
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lda #$03
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sta CHACTL ;Set Character Control
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lda #$84 ;Set color PF2
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sta COLOR2
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lda #$0F ;Set color PF1
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sta COLOR1
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lda #$00 ;Set Display list pointer
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sta sDLISTL
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sta DLISTL
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lda #$10
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sta sDLISTH
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sta DLISTH
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lda #$f8 ;Set Charcter Set Base
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sta CHBASE
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lda #$22 ;Enable DMA
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sta sDMACTL
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lda #$40 ;Enable NMI
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sta NMIEN
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print
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ldy #$00
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cld
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prloop
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lda text1,y ;Get character
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sec
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sbc #$20 ;Convert to ATASCII
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sta $1800,y ;Store in video memory
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iny ;Next character
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cpy #11
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bne prloop
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wait
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jmp wait
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;Display list data
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org $b000
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dlist .byte $70,$70,$70,$42,$00,$18,$02,$02,$02,$02,$02,$02,$02
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.byte $02,$02,$02,$02,$02,$02,$02,$02,$02,$02,$02,$02,$02
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.byte $02,$02,$02,$41,$00,$10
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;Text data
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org $b100
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text1 .byte "HELLO WORLD"
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org $bffd
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.byte $FF ;Don't display Atari logo
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.byte $00,$40 ;Start code at $4000
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