Dave McGuire wrote:

>   Well I don't remember where I got 25MHz, it's been in my head for at 
> least a decade.  But I can tell you for certain that the 78032 on a 
> KA630 is clocked at 20MHz, as I've overclocked a couple of them...so 
> that would seem to support the idea, as I doubt its successor would have 
> a lower clock rate.

Be carefull with the clock rates on a VAX. DEC had a lot of fun with the 
clock circuits on the PDP and VAX. So, there is sometimes an oscilator 
with X MHz, but then it gets divided at least by two, and then they 
start to generate a lot of phase shifted clocks out of this. So,
you can be off very easy ...

Interesting question so:
if a machine has four clocks with 25 MHz, (20/80 duty cycle, 90 degrees 
shift), is it running at 25 MHz, or at 100 MHz ?
;-)

Could be the reason, that DEC specified the cycle time, not the clock 
rate ...

cheers