PIC16f84 program memory question
I think you're getting confused between the word size and the program-counter size:


  The PIC16FXX has a 13-bit program counter capable
  of addressing an 8K x 14 program memory space. For
  the PIC16F84A, the first 1K x 14 (0000h-03FFh) are
  physically implemented (


So you can have 13 bits worth of addressing to get at 8K of 14-bit words.

As you can see in the data sheet, the full 14 bits of each word is used: