Rickard have designed the hardware of the PIC video game system to be able to run several different kinds of games. It has two standard C64/Amiga/Atari joysticks and video and audio output. The processor is a PIC16F84 running at 12MHz and generates both video (PAL and NTSC) and audio in software.  The hardware design is quite simple. The power supply section is just a standard 7805 regulator to get the voltage to 5v, and it has a diode and a cap at the input so it can be fed with both AC and DC (input voltage should be 8..15v something). Two C64/Amiga/Atari joysticks he used as input for the games. Each joystick has four direction switches (up,down,left,right) and one fire switch.

Source: Rickard’s electronic