Re: SID Graphics problem

-----Original Message-----
From: Rodger Boots
Sent: Oct 29, 2010 5:39 AM
To: rasterlist@vectorlist.org
Subject: Re: RASTER: SID Graphics problem

Most all video problems on those old Midway B&W games were caused by bad connections between the two boards.  Graphic movements were done by pulling the image from ROM on the motherboard, then sending the data to the barrel shifter chips on the daughter card, then sending the data BACK to the motherboard and exclusive ORing it with data already in RAM (should have been blank data there).  Then to move object you first erase it by repeating all of the above (erases image in RAM) then redo the above AGAIN with the new image and shift amount.

So, all it takes is ANY bad connection between boards or bad socket on a barrel shifter and the video will go wonky.  This is always a good place to start.

On Wed, Oct 27, 2010 at 9:43 PM, Kevin Moore <talon.k@gmail.com> wrote:

Got a SID that crapped out on me. Not a yoke wiring problem, as this was working fine, and no monitor work has been done.
Using a Braze kit which is known good.

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Invaders appear semi correct, but are split on the ends, and in the wrong order. Shields are split as is the laser base. Plus the laser base is on top shooting down, and scores are on the bottom.