Hey, I have been trying in vain to use a 20Mhz Crystal to do a small program with the FREQOUT command. This is the program I've been using to test the crystals

Main:
High portc.4
Pause 500
Low portc.4
Pause 500
Goto Main

I've tried it with DEFINE OSC 20, ie like this:

DEFINE OSC 20

Main:
High portc.4
Pause 500
Low portc.4
Pause 500
Goto Main

And still to no avail. I have used 3 different PIC18f452's, 2 PIC18f442's and 1 PIC18f252...I have also tried three oscillating crystals, one powered crystal by abracon, and two passive ones by IQ. I've tried the passive ones with 22pf and 10pf capacitors and no capacitors, all to no avail. The same circuits work fine with a 4mhz crystal, I've tried one passive and one powered crystal in the 4mhz range. I've read that due to the breadboards impedance that this could be causing the passive crystals to work incorrectly, but I've even tried touching the crystals directly to the pins and nothing. I just got these crystals and a few of the pics have never been programmed before and once again, the circuits work fine with a slower 4mhz crystal. If someone could help I'm completely mystified as to what's going on.

Let me know if I'm leaving anything dumb out or whatever. Thanks