DS8641N
There is no vendor ID, just a little mark like 2 lightning bolts in paralell
(Like a jagged = sign). So, the questions now are...
1. What's this chip, and what does it do?
2. Can I replace it, or am I just screwed?
National Semiconductor Quad Unified Bus Transceiver. Commonly used
as a Unibus transceiver. Still in production. National lists budgetary
pricing for quantity 1K at $1.15, which means you'll probably pay less
than $4 for a single.
http://www.national.com/pf/DS/DS8641.html
I was surprised to find that DigiKey apparently does not stock it.
3. Is there a way that with only a voltmeter (I
don't have and can't
afford a scope) to verify that the chip's dead? (I'm overly
optimistic too...)
It's dead.
4. What stupid mistake am I gonna make next?
Whatever mistake you're not expecting to make.
Remember the Ultimate Law:
"If something could have gone wrong but didn't, it would ultimately have been
better if it had." Alternatively stated, "If Murphy's Law can go wrong it
will."
And remember, Murphy was an optimist.