RE: [stella] Space Instigators - Final Version (?)

Subject: RE: [stella] Space Instigators - Final Version (?)
From: Nicolás Olhaberry <nolh@xxxxxxxxxxxxx>
Date: Sat, 19 Oct 2002 21:38:33 -0300
----- Original Message -----
From: Christopher Tumber <christophertumber@xxxxxxxxxx>
To: <stella@xxxxxxxxxxx>
Sent: Friday, October 18, 2002 6:49 PM
Subject: RE: [stella] Space Instigators - Final Version (?)

> Hmm, now I'm worried. I've run it on StellaX, Pcaewin and z26 (as well as
a real console) and it seems fine.

I´ve tested SP18 with PCAE 2.1 for DOS and the screen still jitters, but
this seems to be a bug within PCAE.

The problem is here:

F505    8502    STA WSYNC

Because of previous branches, on even frames you reach it at scanline 68,
colorclock 6, and on odd frames at scanline 67, colorclock 225.

On both cases, after WSYNC (I think) you should be at scanline 69,
colorclock 0. But on odd frames PCAE leaves you at scanline 68, colorclock
0, and that makes the rest of the frame to be displayed one scanline

> Dennis wrote:
>>The screen tends to jitter a little. Not jump just kind of a little
>>vertical jitter during game play.

Maybe the 7800 behaves different from the 2600 when you do a WSYNC so close
to the end of the scanline.



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