mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-12-27 14:29:39 +00:00
265 lines
8.9 KiB
Plaintext
265 lines
8.9 KiB
Plaintext
|
|
; Atari 5200 "Hello World" sample code
|
|
; Written by Daniel Boris (dboris@comcast.net)
|
|
;
|
|
; Assemble with DASM
|
|
;
|
|
|
|
processor 6502
|
|
|
|
; ************ Hardware Adresses ***************************
|
|
|
|
DMACTL equ $D400 ;DMA Control
|
|
sDMACTL equ $07 ;DMA Control Shadow
|
|
PMBASE equ $D407 ;PM base address
|
|
CHBASE equ $D409 ;Character set base
|
|
GRACTL equ $C01D ;Graphics control
|
|
PRIOR equ $C01B ;PM priorities
|
|
SIZEP0 equ $C001 ;Size of player 0
|
|
HPOSP0 equ $C000 ;Horizontal position player 0
|
|
COLPM0 equ $C012 ;Player 0 color
|
|
DLISTL equ $D402 ;Display list lo
|
|
DLISTH equ $D403 ;Display list hi
|
|
sDLISTL equ $05 ;Display list lo shadow
|
|
sDLISTH equ $06 ;Display list hi shadow
|
|
CHACTL equ $D401 ;Character control
|
|
NMIEN equ $D40E ;NMI Enable
|
|
sCOLPM0 equ $08 ;Player/missile 0 color shadow
|
|
sCOLPM1 equ $09 ;Player/missile 0 color shadow
|
|
sCOLPM2 equ $0A ;Player/missile 0 color shadow
|
|
sCOLPM3 equ $0B ;Player/missile 0 color shadow
|
|
sCOLOR0 equ $0C ;Color 0 shadow
|
|
sCOLOR1 equ $0D ;Color 1 shadow
|
|
sCOLOR2 equ $0E ;Color 2 shadow
|
|
sCOLOR3 equ $0F ;Color 3 shadow
|
|
|
|
;*************** Variable ***********************
|
|
line equ $20 ;Current DLI line
|
|
pm0pos equ $21 ;Current pos of P0
|
|
|
|
;*************** Start of Code *******************
|
|
|
|
org $4000 ;Start of cartridge area
|
|
Start
|
|
sei ;Disable interrupts
|
|
cld ;Clear decimal mode
|
|
|
|
;************** Clear zero page and hardware ******
|
|
|
|
ldx #$00
|
|
lda #$00
|
|
crloop1
|
|
sta $00,x ;Clear zero page
|
|
sta $D400,x ;Clear ANTIC
|
|
sta $C000,x ;Clear GTIA
|
|
sta $E800,x ;Clear POKEY
|
|
dex
|
|
bne crloop1
|
|
|
|
;************* Clear RAM **************************
|
|
|
|
ldy #$00 ;Clear Ram
|
|
lda #$02 ;Start at $0200
|
|
sta $81
|
|
lda #$00
|
|
sta $80
|
|
crloop3
|
|
lda #$00
|
|
sta ($80),y ;Store data
|
|
iny ;Next byte
|
|
bne crloop3 ;Branch if not done page
|
|
inc $81 ;Next page
|
|
lda $81
|
|
cmp #$40 ;Check if end of RAM
|
|
bne crloop3 ;Branch if not
|
|
|
|
;************* Setup display list *******************
|
|
|
|
|
|
ldx #$21 ;Number of bytes in list
|
|
dlloop ;Copy display list to RAM
|
|
lda dlist,x ;Get byte
|
|
sta $1000,x ;Copy to RAM
|
|
dex ;next byte
|
|
bpl dlloop
|
|
|
|
;************ Setup IRQ vectors *********************
|
|
|
|
lda #$03 ;point IRQ vector
|
|
sta $200 ;to BIOS routine
|
|
lda #$FC
|
|
sta $201
|
|
lda #$B8 ;point VBI vector
|
|
sta $202 ;to BIOS routine
|
|
lda #$FC
|
|
sta $203
|
|
lda #$B2 ;point Deferred VBI
|
|
sta $204 ;to BIOS routine
|
|
lda #$FC
|
|
sta $205
|
|
lda #$00 ;point DLI vector
|
|
sta $206 ;to custom routine
|
|
lda #$50
|
|
sta $207
|
|
lda #$00
|
|
sta line
|
|
|
|
;************* Setup hardware registers *************
|
|
|
|
lda #$22 ;Set color PF0
|
|
sta sCOLOR0
|
|
lda #$0F ;Set color PF1
|
|
sta sCOLOR1
|
|
lda #$84 ;Set color PF2
|
|
sta sCOLOR2
|
|
lda #$00 ;Set Display list pointer
|
|
sta sDLISTL
|
|
sta DLISTL
|
|
lda #$10
|
|
sta sDLISTH
|
|
sta DLISTH
|
|
lda #$f8 ;Set Charcter Set Base
|
|
sta CHBASE
|
|
lda #$22 ;Enable DMA
|
|
sta sDMACTL
|
|
lda #$C0 ;Enable NMI + DLI
|
|
sta NMIEN
|
|
|
|
;************ Draw display graphics *******************
|
|
|
|
ldy #$02 ;Draw bars on screen
|
|
lda #$18 ;Screen memory starts at $1800
|
|
sta $81
|
|
lda #$00
|
|
sta $80
|
|
ldx #$18
|
|
crloop5
|
|
lda #$FF ;Bar 4 pixels wide of color 3
|
|
sta ($80),y ;Store data
|
|
iny
|
|
iny ;Skip 4 pixels
|
|
lda #$55 ;Bar 4 pixels wide of color 1
|
|
sta ($80),y ;Store data
|
|
iny
|
|
iny ;Skip 4 pixels
|
|
lda #$AA ;Bar 4 pixels wide of color 2
|
|
sta ($80),y ;Store data
|
|
tya
|
|
clc
|
|
adc #$06 ;Move pointer to next line
|
|
tay
|
|
dex ;Next line
|
|
bne crloop5 ;Branch if not done
|
|
|
|
;************* Setup Player/Missile registers ***************
|
|
|
|
lda #$3A ;Enable DMA (single line resolution/
|
|
sta sDMACTL ;normal background)
|
|
lda #$20 ;Set PM base address ($200)
|
|
sta PMBASE
|
|
lda #$03 ;Enable players and missiles
|
|
sta GRACTL
|
|
lda #$16 ;Color of player 0
|
|
sta sCOLPM0
|
|
ldy #$00
|
|
lda #$03 ;Size of player 0
|
|
sta SIZEP0
|
|
lda #$01 ;Give players priority over playfield
|
|
sta PRIOR
|
|
|
|
|
|
;************ Copy player data to RAM ********************************
|
|
|
|
pmloop1
|
|
lda pm1,y ;Get data
|
|
sta $2430,y ;Write it into RAM
|
|
sta $24C0,y
|
|
iny
|
|
cpy #$08 ;Copy 8 bytes
|
|
bne pmloop1
|
|
|
|
;************ Move player ********************************************
|
|
|
|
ldx #$20 ;Starting position of player
|
|
mvloop1
|
|
jsr waitvb ;Wait for a vertical bank
|
|
lda #$00 ;Reset line counter
|
|
sta line
|
|
stx HPOSP0 ;Set position of player
|
|
stx pm0pos ;Save position for DLI
|
|
inx
|
|
cpx #$B0 ;Check for end of move
|
|
bne mvloop1 ;If not keep moving right
|
|
lda #$04 ;Give playfield priority player
|
|
sta PRIOR
|
|
|
|
mvloop2
|
|
jsr waitvb ;Wait for a vertical blank
|
|
lda #$00 ;Reset line counter
|
|
sta line
|
|
stx HPOSP0 ;Set position of player
|
|
stx pm0pos ;Save position for DLI
|
|
dex
|
|
cpx #$40 ;Check for end of move
|
|
bne mvloop2 ;If not keep moving left
|
|
lda #$01 ;Give player priority over playfield
|
|
sta PRIOR
|
|
jmp mvloop1 ;Continue looping
|
|
|
|
;************ Wait for vertical blank ************************
|
|
|
|
waitvb
|
|
lda $02 ;Read timer (this is incremented during VB)
|
|
waitvb2
|
|
cmp $02 ;Did it change?
|
|
beq waitvb2 ;If not keep waiting
|
|
rts
|
|
|
|
;************ Display list interrupt ************************
|
|
|
|
org $5000
|
|
dli
|
|
pha ;Save A
|
|
inc line ;Increment the line counter
|
|
lda line ;Past the fifth DLI?
|
|
cmp #$05
|
|
bne done ;If not then exit DLI
|
|
lda pm0pos ;Get player 0 position
|
|
eor #$FF ;Invert it
|
|
sta HPOSP0 ;Set player 0 position
|
|
lda #$0F ;Change player color
|
|
sta COLPM0 ;
|
|
; Note: Player color is changed in hardware register not the shadow
|
|
; register so it takes effect immediatly.
|
|
done
|
|
pla ;Restore A
|
|
rti ;Done
|
|
|
|
;************* Display list data ****************************
|
|
|
|
org $b000
|
|
dlist .byte $70,$70,$70 ;24 blank scanlines
|
|
.byte $48,$00,$18 ;Mode 8 and Load memory scan $1800
|
|
.byte $88,$88,$88,$88,$88,$88,$88 ;23 more line of mode 8
|
|
.byte $88,$88,$88,$88,$88,$88,$88,$88,$88,$88,$88,$88,$88
|
|
.byte $88,$88,$88
|
|
.byte $41,$00,$10 ;Jump back to start at $1000
|
|
|
|
;************* Player shape *********************************
|
|
|
|
pm1 .byte %00111100
|
|
.byte %01000010
|
|
.byte %10100101
|
|
.byte %10000001
|
|
.byte %10100101
|
|
.byte %10011001
|
|
.byte %01000010
|
|
.byte %00111100
|
|
|
|
;************** Cart reset vector **************************
|
|
|
|
org $bffd
|
|
.byte $FF ;Don't display Atari logo
|
|
.byte $00,$40 ;Start code at $4000
|
|
|