Custom Chips

[NM:108]

[NM:110]

[NM:113]

[NM:116]

The Z80 communicates with the I/O Chip through input and output instructions. The state of an 8×8 switch matrix can be read through the Switch Scan circuit. When an input instruction is executed, one of the SO0–SO7 lines will be activated. When a line is activated, the switch matrix will feed back eight bits of data on SI0–SI7. This data is in turn fed to the Z80 through MUXD0–MUXD7.

The Z80 can read the position of four potentiometers (pots) through the A-D Converter circuit. The pots are continuously scanned by the A-D Converter, and the results of the conversions are stored in a RAM in the A-D Converter circuit. The Z80 simply reads this RAM with input instructions.

The Z80 loads data into the Music Processor with output instructions. This data determines the characteristics of the audio that is generated.

[NM:118]