Flashing Light Indicators un Simple Front Panels - test-drb@ccmp.vtda.org

15 Dec 2001

On Dec 15, 14:09, Douglas Quebbeman wrote:
...
  > On Dec 14, 16:16, Douglas Quebbeman wrote:
 >
 > > In particular, do any of you have familiarity with
 > > systems that flash the on or power light as an
 > > indicattor, sopecifiecally, of a power supply
 > > problem?
 >
 > The only thing I can think of that's *designed* to do something like that
...
  > is an SGI Indy; if you power one up and it
can't even run the the code in
...
  > the PROM, it flashes the power light (which is a
two-colour LED).  The
 > usual cause id that there's no (recognisable) RAM at all in it.  Probably
...
   not relevant
to a PR1ME. 
 No, I'm afraid you may have hit it on the head, and it's been the
 direction I've been leaning, that the microcode ROMs may have
 fried, but that just blows my mind. 
Possible, of course, but in the case of an Indy, the processor and PSU are
working, and it gets only as far as the "I think, therefore I am a
processor; I wonder if I have any memory" test in the PROM, and then
executes a loop which controls the LED in the PSU if there's no RAM.  At
least, that's what I believe; I've not seen a detailed description of the
PROM startup.  I suppose your problem may be something similar, in that the
CPU is running but can't do anyting useful because either it's crippled or
some other part of the system is disfuntional.  Does the CPU control the
power supply LED(s), like it does in an Indy?

-- 
Pete						Peter Turnbull
						Network Manager
						University of York