Re: CBM8296D hangs after reset

From: Michael Huth (
Date: 2007-04-22 20:45:06

Hash: SHA1
André Fachat wrote:
> Hi Michael,
> it seems something is flakey in your 8296.
> I don't think it is the PLA, although this ICs breaks quite often.
> Do you have an oscilloscope or logic probe?

I don't own one myself, but as I am doing my PhD at the moment, I
might use one at the university.
Though I have to get the CBM there...

> Dou you have known-working replacement ICs to check whether an IC
> is broken by replacing it and seeing if the problem is fixed?

I have some other Commodore stuff, like 1541 IIs that are still
I could take out chips from there, if I am sure I dont kill them in
the 8296.

> Is the startup beep faster or slower than normal when it beeps?

Normal speed, I guess you are thinking of some IRQ spam?!?

> I had a 8296 with a broken VIA 6522 that had some similar problems
> (booting into the monitor, sometimes with beep, sometimes without.)
>  You may want to check that one first.


> You can check this page, it includes links to diagnostic manuals
> and a page for PLA replacements.
> André
> -------- Original-Nachricht -------- Datum: Sun, 22 Apr 2007
> 17:20:11 +0200 Von: Michael Huth <> An:
> Betreff: CBM8296D hangs after reset
> Hello,
> after about 1.5 years I tried to reactivate my 8296D, but it seems
> to hang now after switching on / or reset. It worked previously.
> The error looks like this: The screen stays black and the CPU seems
> to stop at some point. Most noticeable when the startup sound stops
> with a permanent sound. The floppys seem to reset ok. Once I had
> the screen full of chars, that looked like memory after a power-on.
>  Once it stopped in the Monitor and when I entered 'x' it showed
> ready. and hanged. Once it stopped in the Monitor and the cursor
> ran forward producing random chars, when I pressed shift-clr/home
> it cleared the screen and hanged. If I press reset short, it seems
> to stop in most cases before the startup sound is played. If I
> press reset for about one second it plays the full startup sound.
> I took out and in all socketed ICs, to see if it a contact problem,
>  but it didn't helped. I noticed that UE6 gets quite hot (so hot
> you cant keep your finger on it for some time - if you arent a cook
> ;) ).
> I read in some forums that this error might be a defect PLA (UE6) ?
>  There was also written, that somewhere a reverse engineered ROM is
> in the works, but I couldn't find any.
> So could this error apply to UE6 and if so, where can I get a
> replacement?
> Ciao... ...Micha
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