On Thu, 1 Feb 2001 23:51:58 -0600 (CST), you wrote:
>I recently got my working copy of thrust from hozer and was troubled that
>it didn't work. After a little thought, I realised that it may be a
>compatability issue. So I dug into my closet, and pulled out all my VCS
>compatables.
>
>Here's what I found:
>
>Maker Model Functionality
>----- --------------------- ----------------------------
>Atari 2600 (6 switch) OK
>Atari 2600A (4 switch) OK
>Atari 2600jr (big rainbow) OK
>Sears 2600 (6 switch) OK
>Sears video arcade 2 (2800) Ship is constantly thrusting
>Coleco Gemini Breaks in playfield
>Coleco Coleco with expansion Breaks in playfield
>
>I am most puzzled by the sears video arcade 2 not working, because I
>thought the sears models were produced by atari and just rebranded.
>
>Thomas, do you know what could happen to cause the above problems? Can it
>be linked to an illegal opcode?
>
>Everyone, has anyone else seen similar problems? Has anyone done
>experiments or written other programs useing such opcodes on various
>compatables? Does anyone have a 1-chip jr that they could try?
Yes. The problems with the Colecos are due to a playfield register update
timing issue. I had the same problem in one of my builds of INV - look in
the list archives for April 1997, you may find some info there. The
Coleco TIAs respond differently than the Atari ones to one of the
playfield registers being updated right on the edge of when it's allowed.
Dunno what's wrong with the 2800 though...
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