VAXstation/MicroVAX 2000 CPU/FPU overheating?
ard at p850ug1.demon.co.uk
Wed Feb 27 17:28:43 CST 2008
> One thing that hasn't been mentioned. His system may be
> unintentionally over clocking. I've seen systems where the
> crystal will take of at an overtone. It is even possible that
Interesting. I had an HP9820 where the master clock seemed to be running
at 19MHz (should e 8MHz), but that turned out to be due to the crystal
being cracked in half (I carefully cut the can off it), and the 19MHz was
the free-running frequcny of the TTL gates in the oscillator circuit.
Needless to say the machine didn't work at all...
> the crystal is broken and running at some higher frequency.
> Just a thought
I would guess that the most likely harmonic to jump to would be the
third. Now :
1) I dout very much any machine would be designed to run at a third of
the clock rate that it could run at. Yes, you have some margin, you don't
push things to the limit, but a factor of 3? So if the clock jumped to
the third harmonic, most likely the machine wouldn't work at all
2) Even if it did, I think you'd notice it was running 3 times as fast as
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