Hello Joe,

I have read this question earlier on this PIC list. The 4MHz indication
on the chip is the frequency that is garanteed, by MicroChip, to work
properly. When this uP is used with a higher frequency it probably will
work, but if it doesn't MicroChip can not be held responsible.

Probably MicroChip uses the same process for making the 4MHz and 10MHz
uP's. Only the tests they are running on these chips are different.

Answers to your questions:

- The maximum frequency for reliable operation of a 16c84-04 is
  4MHz !!!!!!!!!

- For not professional use of the uP you can of course experiment with
  the crytal's frequency. The values of the cap's and the settings for
  the oscillator are described in the datasheets.

Hope this will help you.


Greetings:                     ... Sipke de Leeuw ...

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At 10:38 23/05/96 +0100, you wrote:

>I was wondering if many people have used a 16c84-04 at greater than 4Mhz
>using the internal crystal osc. option.
>
>What are the pitfalls of doing this?
>
>If it works now at an elevated frequency will it continue to operate?
>
>What is the maximum frequency one could hope to reliably hope to operate at?
>
>What would the effects of temp. or supply voltage variations be?
>
>What caps should be used?
>
>I've tried a 4Mhz 84 up to 16Mhz with the HS osc. option and no caps.
>It seemed to work O.K.
>
>Any thoughts?
>
>Joe