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John's post makes me remember an old experience from back in the early '80s. A friend and I were attending a meeting of the Valley Computer Club in Burbank California. Members used to bring their computers and other gear to the meetings to show off what they had or were building. The common computer of the day was an S100 box equipped with an Intel 8080 chip. These chips were spec'ed to operate at 2.45 mHz as I recall. At this particular meeting there was one fellow bragging that his computer was the fastest one in the valley. My friend Isaac asked this fellow how he acheved this feat. The response was...

"Oh, I pulled out the 2 meg crystal and replaced it with an LC circuit and a trimmer capacitor. I adjusted the trimmer to top speed and checked the frequency on my scope and read out 3.7 mHz. Is your 8080 that fast?".

The next question my friend asked to this fellow was about how he was able to know what the 'top speed' setting of the trimmer capacitior was. The fellows reply to that was....

"Very simple. I enter a BASIC program as:

Save This Code

   10 FOR I=1 to 1000
   20 PRINT I
   30 NEXT I
   40 GOTO 10

And then while the program is running I adjust the trimmer up till the program stops displaying numbers. Then I back off a little and that is the setting, 3.7 mHz".

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It is a good story to laugh about but the implied consequences of running components out of specification range is indeed a scarry thought.

Michael Karas