🚀 go-pugleaf

About three weeks ago, the power supply on my antique (16K RAM chips
on the motherboard) IBM PC broke.  In the process of replacing it, 
SOMETHING happened to it, with the result that it powered up with
two long beeps and one short one (or something like that).  According
to the Guide to Operations manual, this indicated a problem with
the System Unit (please take to your local repair facility and surrender
your wallet).

Of course, I assumed that something had been damaged on the motherboard,
perhaps because of the power supply failure.  Fortunately, Kontron
Electronics makes logic analyzers, and we have lots of neat test 
equipment around (that's our business), and after several hours of
studying the signals on the backplane and the display controller card,
my colleague Brad said, "Gee, it looks like it's trying to write to
the color monitor memory."  At which point I said, "Gee, I wonder if
the DIP switch on the motherboard that selects the monitor got altered."
You see, on the PC this particular DIP switch is right next to the
plugs for the motherboard power supply.  (On the XT, it's quite a ways
away.)  Of course, this was the case.

Why, oh why, couldn't IBM make the BIOS smart enough to distinguish
"wrong or missing display adapter" from "system unit error"?

At least I didn't end up buying a new motherboard.