16x84 is the generic name for the Microchip 16c84 and 16f84, which are almost the same. For a jal programmer the only difference is that the 16f84 has 68 file registers (RAM bytes), the older 16c84 only only 36. The other differences are taken care of by the pragma's in the target specification files.
The 16f84 is a single-chip microcomputer in an 18-pin package. 13 pins are available for general-purpose I/O. The chip has 1K of electrically (re-) programmable program memory, 68 bytes of RAM (called registers in Microchip terms) and an 8-level return stack. There is no simple way to expand any of these on-chip resources. Most instructions take four clock cycles, so the CPU horsepower is 2.5MIPS at the maximum clock frequency of 10MHz. Instructions which change the PC (goto, call, return, btfss, btfsc and instructions which manipulate the PC directly) take eight clock cycles.