[Coco] 6821 PIA Chip Bad?

[Eric Keppel]

Hi Coco Folk!

Well, I purchased another Coco on eBay, and unfortunately, it got lost
by the USPS for about a month and then suddenly appeared at my door
yesterday.  The delay was caused by the box ripping apart, and the Coco
obviously fell out and got caught on a conveyor belt or something.  The
case is really beat up now and the power and reset button are missing.

Anyway, I powered it up and it wouldn't boot (garbage on the screen,
sometimes an orange screen, and once in a while the ECB 1.0 message,
missing key presses from some keys).  Even when it would manage to boot,
it would always lock up in about 60 seconds or so.

I cracked the unbroken warrantee seal (bummer) and opened it up to have
a look.  It's an older gray Coco1 with a Rev. E board and 16k.  After
checking that all of the various chips were seated well, I noticed that
one of the 6821 PIA chips was running VERY hot.  I just about burned my
finger on it.  Well, I swapped the two PIAs with one another and it
booted right up nicely, but didn't stay up for very long, then that same
PIA chip got hot again and the machine locked up.

So, I am suspecting that the hot PIA is bad since it got hot regardless
of which socket it was in.  In fact, when I put my finger on it, the
machine stayed up much longer, presumably because my finger is acting as
a heat sink and keeping the chip going a little longer.  This is very
unscientific, but my best guess.

I see that the chips aren't too expensive, so I was thinking of getting
one to replace it unless someone has a better suggestion or sees
something I missed.  Am I on the right track?

--Eric