Of course, indeed I'm quite sure many folks here have
I'm sure you are aware though, that although the PIC16F84A is still available, it is now an obsolete part and should not be considered for a new design. There are plenty of new devices from Microchip now to replace it with, all with loads of different features and peripherals onboard. Download a few datasheets from the Microchip website and have a good read through them to familiarise yourself with what is now available.