Re: [stella] Gravity Ball v015 - Thanks!

Subject: Re: [stella] Gravity Ball v015 - Thanks!
From: R Mundschau <rmundsc@xxxxxxxxx>
Date: Wed, 04 Jun 2003 11:23:57 -0500

> From: "Dennis Debro" <ddebro@xxxxxxxxxxxxx>
> Reply-To: stella@xxxxxxxxxxx
> Date: Wed, 4 Jun 2003 06:30:10 -0400
> To: <stella@xxxxxxxxxxx>
> Subject: RE: [stella] Gravity Ball v015 - Thanks!
> Hi Rob,
> I've got one more (sorry I didn't see this before). You're doing 30 scan
> lines for overscan. Then before doing vertical sync you do one more
> WSYNC. This gives you 263 scan lines. This is okay as most TVs should
> show this fine.
> I'd suggest your vertical sync to be...
> LDX #44
> LDA #02
> STA WSYNC  ; sync with end of last line of overscan from previous
> frame.
> STA VSYNC  ; Enable vsync (happens at the beginning of the scan line)
> LSR        ; a now 0 saves a byte too--right Thomas ;)
> STA WSYNC  ; vsync for 2 scanlines
> STA VSYNC  ; end VSYNC (happens at the beginning of the scan line)
> Then in overscan, reduce the scan line loop to 29.
> Having VSYNC happen at the beginning of the scan line will guarantee
> that even the sensitive 2600 (mainly jr's) will play the game fine. I
> think Eric Ball did some research on this a while back. It's just one of
> those "safe" things to do :)

Thanks for the tip!  One of the lingering questions I have had about the TIA
is when do I need to set VSYNC to have it count for a whole scanline.  Then,
when to turn it off so as to get exactly 3 lines of VSYNC and not 2 or 4.  I
will use your code suggestion.    Thanks


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