28 May
2008
28 May
'08
9:49 p.m.
Fred Cisin wrote:
What you have found is called a Power On Self Test
card, or "POST card".
During the cold start process, the computer sends numbers at various
stages to a port. By putting in a card that decodes the port and displays
those numbers, you can see which stages of the start up process succeeded.
It will only work if the computer is making it at least partway through
the cold start boot process, and will certainly not tell you anything if
the CPU is dead, no matter what some brain-dead moron might say. (Well,
OK, some also have a few LEDs to tell you if the power supply is live,
etc.)
It was my understanding that only AT-class machines (by age, not
necessarily by architecture type) wrote to that port. I've never seen a
PC or XT (or clone thereof) motherboard/BIOS write to that port.
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Help our electronic games project: http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
A child borne of the home computer wars: http://trixter.wordpress.com/