Re: very strange C64 fault

From: Francesco Messineo <>
Date: Tue, 18 Apr 2017 13:34:58 +0200
Message-ID: <>
On Tue, Apr 18, 2017 at 1:20 PM,  <> wrote:
>> On 2017-04-18, at 13:05, Francesco Messineo <> wrote:
>> Hi all,
>> I have found a real tricky fault on my C64C. I'll try to describe the
>> symptoms, in case anyone is curious enough to help in troubleshooting
>> it. I am not a newbie in repairing C64s, but this one made me just
>> wondering without even giving me a clue on where to start probing for
>> possible faults (if I had a logic analyzer I would know what to do,
>> but I haven't got one).
> Logic analysers may not help in some edge cases like this one.
> The nouns you mention (VSP, sprites, ..) seem to be pointing towards the VIC. I'd check its voltages, frequencies and eventually swap it.

no VSP errors showed from a tool that's supposed to check for their
existence on a C64, so yes, the VSP was mentioned and likely excluded.
The crashes are very repeatable infacts, all happens every time at the
same point of some programs. Most (all I could try) programs show no
random or repeatable errors.
I don't have any other MOS 8565 VIC-II chip to try swapping it. I only
have old 6569s


       Message was sent through the cbm-hackers mailing list
Received on 2017-04-18 12:02:04

Archive generated by hypermail 2.2.0.