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; this file needs to be assembled with:
; cl65 -o newtitle.xex -t none newtitle.s
; It contains only an init routine, no run address.
.include "atari.inc"
; where our screen was loaded (see newtitle.pl)
screendata = $3000
; homebrew atari xex header
.word $ffff
.word start
.word end-1
.org $5000 ; anywhere that doesn't step on the title data at
; $3000, and doesn't cross a 1K boundary (since there's
; a display list included here)
; executable code here
start:
; setup color registers
lda #$c0 ; dark green
sta COLOR2 ; text bg
lda #$0c ; white
sta COLOR1
; turn off screen, in case vblank happens while we work
lda #0
sta SDMCTL
; wait for the next frame, to avoid graphics glitching
jsr wait1jiffy
; setup our display list
lda SDLSTL
sta FR0
lda SDLSTH
sta FR0+1
lda #<dlist
sta SDLSTL
lda #>dlist
sta SDLSTH
; switch to narrow playfield, enable screen
lda #$21
sta SDMCTL
; clear any keypress that happened during loading
lda #$ff
sta CH
; wait for user to press a key
wait4key:
lda CH
cmp #$ff
beq wait4key
; eat the keypress
lda #$ff
sta CH
; restore OS's display list
lda #0
sta SDMCTL ; disable screen again
lda FR0
sta SDLSTL
lda FR0+1
sta SDLSTH
jsr wait1jiffy
; switch to normal playfield, enable screen
lda #$22
sta SDMCTL
rts ; return to DOS
wait1jiffy:
lda RTCLOK+2
wait:
cmp RTCLOK+2
beq wait
rts
; display list here
dlist:
.byte $70 ; 24 scanlines of blanks
.byte $70
.byte $70
.byte $30 ; 4 more since image is only 184 lines tall
.byte $0f | $40 ; LMS, BASIC mode 8
.word screendata
.repeat 127
.byte $0f ; 127 more scanlines of mode 8
.endrepeat
.byte $0f | $40 ; Hit 4K boundary, LMS again
.word screendata+$1000
.repeat 55
.byte $0f ; 55 more scanlines of mode 8
.endrepeat
.byte $30 ; blank 4 lines to match GR.8 (does it even matter?)
.byte $41 ; JVB, jump & wait for vblank
.word dlist
end:
.word INITAD
.word INITAD+1
.word start
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