Nichole Petty <PHXSYS@AOL.COM> asks:
> Can I run a 16C84 at 20 Mhz? If not what is the fastest speed for proper
> operation ?

At 5V and 25C, the 16C84 seems to run reliably at 16 MHz, but not at 17 MHz.
The 16F84 is a newer part, so it might use a newer process and run faster.

That's find for experimentation and perhaps prototyping; for instance, I
ran the 16C84 at 16 MHz for my prototype closed-caption decoder, then
switched to the 16C622 which is available with a 20 MHz rating.  However,
I would never design a product that pushed the part beyond the rated
specifications.

Cheers,
Eric