On Tuesday 15 July 2003 19:49, jesse@xxxxxxxxxxxxx wrote:
> life of me I can't find any comprehensive documents explaining how to do
> timing on the 2600 (I've been trying to count scanlines, but I think I need
> a little guidance). Anyway, if anyone has any suggestions (or code samples
What you're trying to do is actually pretty different than what people usually
talk about as "timing" on the 2600. You basically have a screen A you want
to display and a tone you play meaning "keyed" and another (presumably blank
and silent) screen B for "open".
Try adapting one of the "how to draw a playfield" tutorials such that every 60
frames it switches between screens A and B. You could make screen B
something like
(pseudo-code)
ScreenB:
LDY #192
LoopB:
STA WSYNC
DEY
BNE LoopB
; and then vblank... set your volume to 0 there
You really don't have to worry about scanlines or cycle counting at all except
to make sure you end up with the same number of lines in both ScreenA and
ScreenB (and of course that they're close to 262/312).
Rob
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