derbiangames@gmail.com wrote on 07. January 2016:
>
> I have a '83 breadbin C64 that glitches in one particular demo called
> "Parts" (http://csdb.dk/release/?id=11689). It always happens during
> the first part of the demo (intro text / vector buildings). Either
> short flashes of garbage characters on the screen, or sometimes the
> graphics completely mess up and the demo freezes, accompanied by an
> abnormal sound.
>
> The strange thing is, I have run 100s of different demos/games on this
> machine and this is the ONLY one that doesn't work properly.
>
> I've already ruled out the following:
>
> -Disk/drive problems (tested with a known working drive, and another floppy)
>
> -VSP problems (the VSP test shows no problems on this machine. Another
> C64 I have DOES have VSP problems but it has no problems running this
> particular demo).
>
> -Faulty PSU (tested with another one, no change)
>
> -Tested with another breadbin, same cables and equipment -> no glitch
>
> -Both breadbins are PAL models
>
> It's not a big issue since it only affects this one demo, but I'd still
> like to solve this mystery. Maybe some tiny timing issue that only
> affects the most sensitive programs? RAM, CIA, PLA, SID and VIC are
> socketed, and some of them have had contact problems in the past. But
> it's unlikely that would affect just ONE program. And since some of the
> sockets are already pretty worn out, I'd prefer not to put more stress
> on them unless needed.

[...]

Can't help. Just mention when I got an Amiga 500 in 1989 with a similar
problem. I had to return the first and also its replacement. Although
both worked fine they both wouldn't play a specific demo. I really had a
hard time to return the second one because the clerk couldn't believe two
Amigas sold to me wouldn't work.

Anyway, got a third and that would play the demo. May be it was from a
different plant or used a chip from a different manufacturer responsible
for the problem.

Oh. And the very first Commodore 64 I bought late 1983 just had garbage
on the screen when just turning on. Had it replaced and that one served
me well for the next 6 years until I sold it.
--
Andreas

I use a Unix based operating system, which means I get laid almost as often
as I have to reboot my computer.

--- SoupGate-Win32 v1.05