[rescue] Perverse Question

[Dave McGuire]

On Saturday, June 7, 2003, at 07:51 PM, Michael Free wrote:
> If I remember right, in classic terms (XT, the last time I dealt with 
> it)
> "SENS" or "Power Good" is an input.... the motherboard can tell the 
> power
> supply if the power is good. You can route this to ground (iirc) with a
> momentary switch for a reset button, something the IBM PC and XT was 
> sorely
> lacking.
>
> Luckily they had a little removable panel in the back which made 
> drilling a
> hole for the switch much, much easier :)

   Actually the "Power Good" signal is an output from the power supply.  
On better supplies it's a logical AND of the output of a group of 
window comparators which check that each output voltage is within 
tolerance.  On cheaper supplies (and all modern PC supplies that I've 
seen) it's simply a signal that goes active after a short delay 
following powerup.  It is the intention that the processor not start up 
until that signal is asserted.

       -Dave

--
Dave McGuire             "I've grown hair again, just
St. Petersburg, FL           for the occasion."       -Doc Shipley