I got my interface test unit built and running.

To my surprise the times were not as expected. 241, 482, and 964 milliseconds
not 250, 500, and 1sec. I had double checked in MPLAB and I am using the
right number of cycles. My problem is my crystal is 4% high in frequency.
About 4.16 to 4.18 depending on where I try to measure it.

I am using a 16c84 rated at 10mhz, a 4.000mhz crystal and 2 22pf caps from
Digikey. I set the oscillator bits to HS. The unit was built on one of MEL's
proto boards.

What are the key factors I need to look at when I need the oscillator to be
within 0.1% without tweaking the frequency?

I really thought I could just grab a 4mhz rock and a couple caps ant it would
be at least as close as I need. Should I consider using a canned dip oscillator?


Another question is can you use a solder less breadboard (I just got one of the
E.N.D. unit's) and a 20mhz clock on a 16c65 windowed part. I have concerns that
the oscillator will go nuts with all the stray coupling, and I will need 0.1%
accuracy on that unit too.