Andrew Davie wrote:
> Code follows. The routines VBPreliminary and VBFinal were not included in
> the byte-count, as they were already used for the other kernal display -
> they've been re-used for the title screen. That is, there was no
> title-screen-related cost in using them. This is the preliminary
> (not-very-much-optimised) title routine, and as you can see its pretty
> simple. The best bit is how I packed almost full-screen graphics into just
> 4 bytes/line, just 6o bytes for the total screen graphics (I'll optimise-out
> those trailing 0's later). Total is about 180 bytes.
Thanks for the code!
BTW: a little optimization:
VBPreliminary
lda #D1+D6
sta VBLANK ; start with tia disabled
; lda #D1
sta WSYNC
sta VSYNC ; start vertical synch
;just use the old contents D1+D6, VSYNC doesn't have a valid bit 6.
sta WSYNC ; 1st
sta WSYNC ; 2nd TV SYNCH (2 tested OK on PAL, 1 FAILED)
sta WSYNC ; 3rd, to satisfy ES :)
IF COMPILE_VERSION = PAL
ldx #72 ; PAL
ELSE
ldx #31 ; NTSC
ENDIF
stx TIM64T ; 40/48 scan lines -2 (above)
; lda #0
lsr
sta VSYNC ; stop vertical synch
rts
;you could also write stx VSYNC (PAL only), but then there is a dependency with the timer values.
Or you can even try this:
VBPreliminary
lda #D1+D6
sta VBLANK ; start with tia disabled
ldy #4
.loop:
sta WSYNC
sta VSYNC ; enable/disable vertical synch
dey
bne .loop
tya ; or asl
beq .loop ; bmi .loop
IF COMPILE_VERSION = PAL
lda #72 ; PAL
ELSE
lda #31 ; NTSC
ENDIF
sta TIM64T ; 40/48 scan lines -2 (above)
rts
Have fun!
Thomas
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Thomas Jentzsch | *** Every bit is sacred ! ***
tjentzsch at web dot de |
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