Subject: [stella] Timers and scanlines From: "John K. Harvey" <jkharvey@xxxxxxxxxxxxxxxxx> Date: Sat, 08 Jul 2000 08:57:34 -0400 |
Howdy all. According to Nick Bensemma's How to Draw a PF, (http://www.io.com/~nickb/nbtia_1.asm) To set up the VBLANK timer for 37 scanlines, we do: (37 scanlines )* (76 cylces per line) = 2888 Subtract (5 cycles timer set) = 2883 Subtract (3 cycles WSYNC) = 2880 Subtract (6 cycles for checking loop) = 2874. And 2874 / 64(timer) = 44 for the timer load. Voila! Here comes the tricky part: I don't suppose there is an available list somewhere of what timer to set, and its setting for scanline counts from 1 thru 37? I just figure it may be easier if a document were availble instead of doing all that math. Anyone know of any? Also, is the 2880 part of 2876/64 in Bensema's document supposed to be 2876/64? Because 2880/64 = 45. So, what's correct? Thanks. -John K. Harvey -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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