Player Input

The system accommodates up to four player control handles at once. Each handle has five switches and a potentiometer. The switches are read by the Z80 on input ports $10–$13 and are not debounced. The switches are normally open and feedback 0's.

The signals from the potentiometers are changed to digital information by an 8-bit Analog-to-Digital Convertor. The four pots are on input ports $1C–$1F. When the pot is turned fully counter-clockwise, it feeds back all 0's; when turned fully clockwise, it feeds back all 1's.

The 24-button keypad is read on bits 0–5 of input ports $14–$17. The data is normally 0, and if more than one button is depressed, the data should be ignored. The keypad will not send back proper data if any of the player control switches are closed. Keypad buttons are not debounced.

Player control inputs are illustrated below:

[NM:101–2]