Hi,
When I use:
16f877-20 P - 4MHz,16F877A - I/P - 4MHz (DEFINE OSC 4)
work fine but,

16f877-20 P - 20MHz (DEFINE OSC 20) - Work
16f877A - I/P - 20MHz (DEFINE OSC 20) - Don't work

Whats wrong ?


Tnx