Subject: [stella] Re: robbie.a65 From: mor@xxxxxxx (Greg Troutman) Date: Mon, 14 Oct 1996 10:04:55 -0700 |
>Top: ; Start a new screen > > LDA #$05 > STA Tim64T ; set timer for $05*$40 = $140 (320d) clocks There are 228 color clocks per scan line. The RIOT timer intervals once every 3 color clocks. Thus a scan line should take 76 ticks of the interval timer (228/3). There are 30 scan lines in overscan. Thus you need to count 2,280 (30 * 76) on the timer. Using the 64interval timer, you get 35 ticks. Not 5. Or something like that. > LDA #$05 ; put $05 in A > STA Tim64T ; start vblank timer Similar math here for 37 scan lines of vertical blank. Your programs work fine on the emulators, except you lose the bottom half or so of the screen (it's just blank) because you're not waiting long enough before doing VSYNC or while you VBLANK. Increasing these waits should fix it no problem. Sincerely, gt (mental as anything)
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