This Games Port Tester, or GPT, is arguably the simplest possible way to check to see if the games port is functioning correctly.

Initially, the project was created to test and experiment with the quality and accuracy of the games ports on various low-cost sound cards. But it is just as happy testing the games ports which are fitted to most PCs.

It will test both sides of the port – Player 1’s "X" and "Y" axes and fire buttons and similarly Player 2’s "X" and "Y" axes and fire buttons. This is accomplished by simply flicking a switch.

The software written to suit this project features an auto calibration control and toggle control between both players, along with smooth, sprite-free graphic movement on the 100K and 200K systems.