Re: Overclocking VAXen

From: Chris Scheers (chris_at_applied-synergy.com)
Date: 05/24/03 

Date: Fri, 23 May 2003 17:45:10 -0500

Antonio Carlini wrote:
>
> JF Mezei wrote:
> > But wasn't Digital fairly conservative with the speeds of its CPUs ?
> >
> > For instance, for the microvax II, would Digital have pushed the limit of the
> > chip's speeds, or would it have been satisfied with a .9 VUP speed that
> > wouldn't compete against bigger vaxes ?
>
> In the case of the uVAX II, I think the CPU ran at just the
> right speed to match the memory interface. Maybe other
> systems could have been sped up a little. If you go back
> to the older, larger systems, such as the VAX-11/780 and
> the VAX 8600, you could run the clock up to about 5%
> faster to try and flush out marginal components. (And I
> think you could margin the voltages too...)

Correct, the uVAX II was designed so that the memory cycle (I think it
was 400ns) meshed with the clock cycle so that there were no wait
states.

This also meant that there was no need for a cache.

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