Re: very strange C64 fault

From: Francesco Messineo <>
Date: Sun, 23 Apr 2017 18:53:47 +0200
Message-ID: <>
Hi All,
final update: it was the CPU, fortunately it was temperature
sensitive, so when cold it would take a few minutes to show the fault.
So cooling the various chips with compressed air just showed the real
It's my first broken 8500 and also the only 8500 spare was used to fix
the C64C :/
However, the Lunatico demo still freezes when pressing F8 from the
Note and VSP tool, but runs fine when started directly.
All other freezing programs now work fine.


On Tue, Apr 18, 2017 at 2:13 PM,  <> wrote:
>> On 2017-04-18, at 13:56, wrote:
>> From your description of a sprite "almost?" touching the bottom of the
>> screen... And the fact that it's always at the same position, so that it's
>> really repeatable points to a logic error, not a timing error.
>> Maybe it's a stuck sprite collision bit, that once set is not reset and keeps
>> the interrupt low?
> For one, good example.
>> You could write a simple test program for that.
> Or check with the scope what happens with e. g. _IRQ line when it freezes. Putting in a freezer car and checking if you get a repeatable freeze state when it happens may also help. Provided you have an AR or similar.
> --
> SD! -
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Received on 2017-04-23 17:00:02

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