Say,
        I'm trying to graduate from using RC timing in my PIC projects so I
spent the last week working on a motor speed control program and circuit
that is based around a 4MHz crystal.  I must be missing some fundamental
concept because with everything else the same, the circuit works with RC
but not the crystal.

        Is there more to using a crystal than placing it between OSC1 and OSC2
and using two 15pF caps to ground?  (incidentally I am using both a 54
and an F84)

many thanks & best regards,
Pete
peter.cesarz@appl.ge.com