Your question here was how fast a PIC can go beyond spec.  Well, you
run -04 at 20MHz.  That's 5 times beyond spec.  Considering this, PICs
are quite fast.  Even if -04 and -20 are the same die, perhaps a -04
only passes 98% of the tests at 20MHz.  I don't know if that may be a
peripheral that would show periodical flaws or whatever.
Either way, you will see more and more parts failing as speed
increases beyond spec.  There has been made software designed to run
on a 16C54 at 70MHz.  Only one of four parts could do it, and they
were quite hot.

-DS
Speed Kills! Use Windows 95.


Thursday, September 16, 1999, 8:29:21 AM, you wrote:

TC> had a problem.  I would question whether the testing is different
TC> or if it is just the price.  The cost for the distributors to
TC> inventory all these 'different' flavors of the same part (die) has
TC> got to be more that the cost of the fallout between a -04 and a
TC> -20.  Why not label all the parts at max published die speed, cost
TC> reduce the products by inventory reduction, and

TC> fully agree with you that  to design a circuit using clocks
TC> greater than the max published clock speed would be career
TC> suicide, but my curiousity still asks: How fast can a PIC go
TC> beyond the specs.? (not that I'd ever run it at that speed in a
TC> commercial design)

TC> Todd