HPWM uses the HARDWARE PWM MODULE within your PIC. It allows your program to do other things whilst it happilly functions in background.

PWM generates a PWM string of the duration specified by the PWM command. It then STOPS whilst your program executes other commands.

When you've downloaded the Datasheet for the PIC16F84A you will discover it doesn't have a Hardware PWM Module, so you can't use HPWM with this chip even if you wanted to.

Read the Datasheet!!!