[stella] Qb/playfield timing
Subject: [stella] Qb/playfield timing|
From: Glenn Saunders <cybpunks@xxxxxxxxxxxx>
Date: Mon, 05 Feb 2001 20:36:31 -0800
For the record, what is the right cycle count after WSYNC to rewrite the
playfield registers for the right half of the screen?
I took a look at Qb and I'm trying to understand the cycle count notations.
; right pf
lda playfield+2,x ; 4
sta PF0 ; 3 < 49 (now@42)
lda TargetDisplayL,y ; 3
sta PF1 ; 3 < 55 (now@48)
lda TargetDisplayR,y ; 3
sta PF2 ; 3 < 66 (now@54)
Does this mean that
PF0 must be rewritten somewhere around cycle count 42-49,
PF1 between cycle count 43-55, and
PF2 somewhere between 54 and 66?
I'm just wondering what the exact min-max cyclecounts for each write so I
can maximize time for inserting the sprite register routines in my game.
I can surely experiment, and probably will, but I was hoping this was
documented somewhere already.
Also, I am having trouble digging up the INV sources from the
archives. Could someone point me in the right direction?
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Andrew Davie - Mon, 5 Feb 2001 01:50:04 -0500 (EST)