1. Get rid off 16F84. It does not have Hardware Serial Port. It is old. It is too expensive too. From direct.microchip.com you can order whatever you want at very low cost.

2. If you insist on using the F84 part, you have to change the commands from HSERIN/HSEROUT to SERIN/SEROUT or SERIN2/SEROUT2 as these are the software commands. Read the Manual for these. Almost the same as the hardware ones.

But I really do recommend to use other chip.

Ioannis