On Thu, 6 Nov 1997 16:23:26 EST XYGAX <XYGAX@AOL.COM> writes:
>Try it .
>It will probably work is only 30% overclocked it may result in a 5-10%
>fall
>out most bits will work over speed. During testing try at both
>extremes of
>voltage and tempreture to qualify sucessful opperation...

I've had one work at 16 MHz, but not work at 20 MHz.  Another circuit has
worked with several chips at 12.5 MHz.  All these tests were with 5V and
room temperature only.  I suspect the slow part is the program store, so
it won't matter much whether it uses a crystal or external clock.

At high speeds you may want to give the ports and EEPROM more time to
work.  For example don't use any consecutive RMW's on the ports.   I
don't know if the EEPROM logic forces it to read in one instruction
cycle, or if there is some benefit to waiting an extra cycle before
reading the EEDATA register.