Re: 'Frankenstein' Disk Drives, Done Cheap

From: smf <smf_at_null.net>
Date: Mon, 28 Apr 2014 21:40:56 +0100
Message-ID: <3444CEF0505A462BA40531901997B46D@smf>
>During normal (boring) operation this problem never happens.

I believe if you are trying to do some boring split screen scrolling, but 
choose the "wrong" cycle to write the registers then you can hit it by 
accident.

Codemasters red max always crashed my c64 after about a second & it has a 
really glitchy raster split with garbage. I never tracked down what upset it 
though.

>Yes, but why exactly? The CPU has handed the value (whatever it is) to the 
>register hundreds of ns before VIC puts his addresses on the bus. 
>Everything should be stable by then. Why isn't it? And this only happens on 
>some VICs, others don't have that problem.

VIC assumes certain things have been done in previous cycles based on what 
it knows now. Which is pretty much how all the VIC effects work (opening the 
borders etc).


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Received on 2014-04-28 21:06:13

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