[stella] Timers and scanlines

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,
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?

	-John K. Harvey

Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/

Current Thread