The program to drive the game replaces the code using the keyboard
exactly, apart from the delay routine which follows the end of the
The program executes from D00H, starting with PIO
then jumping to the original program.
|Scans the switches, will allow firing of a
missile whilst moving left or right.
|Fires a missile as per original program.
|Prevents more than one missile being fired
|for each key depression.
|Move left, as per original program.
|Initialises PIO; Starts program.
|Move right, as per original program.
|Controls speed of movement, by value at FD4
In principle, the ideas given above can be adapted to suit many games.
The unit makes
much easier to play and saves wear and
tear on the keyboard when hitting the keys in the excitment of the