Re: [stella] How do I count WSYNC?

Subject: Re: [stella] How do I count WSYNC?
From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney)
Date: Mon, 24 Aug 1998 23:53:57 GMT
>I guess the question comes down to this:  How many cycles do I have 
>"_between_ WSYNC's"?  I think if I just use all 76 cycles, I don't have 
>anything to worry about, but I also think that if I use 73 cycles then 
>hit WSYNC like this:
>LF0BB: STA    WSYNC   ;3
>... my timing will be off.  Anyway, I hope that's the case, because right 
>now a line that's taking 76 cycles including a sta WSYNC (I'm counting 
>the WSYNC as three cycles) is acting like it's screwing up!

STA WSYNC requires either four or five cycles to work properly.  Both
numbers have their advocates on this list; I believe it's five.  You're
correct in that if you just use all 76 cycles, you don't have anything to
worry about, but you must make sure it's 76 cycles *every* time - no
branching, or fetches across a page boundary.  At any rate, you're safe if
you use 71 cycles and then do a STA WSYNC.

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