Try one thing first.

Connect your PIC16F84 to your PC and send some data to any terminal softare (hyperterminal, TeraTerm, RealTerm, Microcode Serial communicator) and see if you receive any data.

do the same but From your PC to your 16F877,

once both work, try your PIC to PIC communication on small distance, then move on with long cable run. You may want to use RS232 driver for longer run.