>> It will run fine (probably). I hooked up a 16mHz >> x-tal to a 4mhz F84 with no problems. What is the all time speed record for running a F84, 16,20,30 MHz? If you do push a pic too far will it still work at it's rated speed after? Maybe I'll give it a try, now where did I put that 1 GHz x-tal ;-) Ken Kaarvik