enpassant wrote:
>
> The PIC 16F84 Data Book specifies that you should use a parallel cut
> crystal in lieu of a serial cut crystal or the clock frequency will be
> inaccurate.  What is the difference between these two cuts, and how do
> you know which kind you are getting when you when purchasing a crystal?
> Thanks.

The crystals are specified for paralell or serial operation. The circuit
that the crystal is used in, determines which one you want. All crystals
have paralell and series modes, at two different frequencies. So, if you
put a series crystal into a paralell circuit, you can't get it to run at
the specified frequency.

Have a look at www.digikey.com they have plenty of xtals online, and
you'll see how to order either kind.