MicroPose (MicroProse?) - do the Micro2000, which is a rather useful POST probe.....
It's not cheap, but well worth it for the usefulness, it is listening address configurable, and will provide extra diagnostics like Osc check, clock check tri state logic probe, and of course all the voltages....
We *could* make our own. A POST card is an ultra-simple device, It simply latches data from a specific port reserved for POST (I forget which one off-hand though) and displays it via either a bank of 8 LEDs in binary or two 7-segment LED displays in hex.
...
If you're looking for a basic functionality POST card, I did a quickie web search and came up with several. Check out:
http://www.datadepo.com/mpost.htm
http://www.micro2000.com/postprobe.htm
http://www.quicktech.com/qppcplus.htm
They vary wildly in price, but I found a local distributor for the megacode ISA-Bus only product and went out this afternoon to pick one up for US$30 (+ $2.45 local sales tax.). A lot less painful than rolling my own...
And the standard POST port is apparently 0x80.
Cheers!
Phil King pking@netschools.net