PC/AT "power good" problems

[Chuck Guzis]

On 05/28/2016 02:37 PM, Richard Cini wrote:


> Basically, the PC won’t come out of reset. I tested the power supply
> with a load tester specifically for PC power supplies and it reports
> power_good and all voltages look good on a meter. So far, so good. I
> dug out my ISA POST diagnostics card which also has a PG tester in
> it. This reports no_PG but I do see the reset pulse on the bus. Not
> sure why one would report OK and one not.

Exactly what do you mean by "won't come out of reset", Rich?  How can
you tell?  Is RESET on the ISA bus always active?

Bear in mind that the PC AT BIOS during POST goes through some rather
arcane protected-mode memory tests, using the CMOS "why did I get here"
byte when coming out of reset.

--Chuck