This is a programmable interface card for accessibility peripherals that can read inputs from the input devices and emulate a keyboard, joystick, or mouse. It contains a dedicated 65C816 16-bit CPU with 32K of RAM to hold the program code. There’s a supercapacitor on the board which allows the low power SRAM to retain the program code for days so that the user doesn’t have to boot up the configuration disk every time the computer is powered on.

Although I believe this card is primarily designed to work on the Apple IIgs (and the only software disk I found is for the IIgs), when DIP switch 2 is turned on it will pull down a IIgs-specific bus signal so that the card might also be able to work on an Apple II+ or IIe.

The card connects to an external breakout box which breaks the signals out onto a 36 pin centronics connector. The box doesn’t contain any active circuitry and mainly just passes the signals straight through to the centronics connector. The two mono 3.5mm jacks use signals shared with the centronics connector and were used for simple/inexpensive input switch devices. The pinout of the centronics connector shown in the manual shows in a little more detail the use of each connection.

In order to transparently emulate the standard Apple II input devices, the card looks like it has the ability to trap read & write requests that are directed to I/O memory locations and take them over. There is dedicated hardware to identify when any (configurable) set of I/O memory addresses are accessed, stop the IIgs’s CPU, and send an interrupt to the card’s dedicated CPU for further handling. The program running on the card could then take over the entire Apple II system using the DMA mechanism and eventually place a value on the data bus and resume the IIgs’s CPU.

The PCB doesn’t label any of the components so I’ve taken the liberty of assigning identifiers so that the PCB can be cross-referenced with the schematic.

Schematic

Box Schematic

KiCad Project & all artifacts

Manual

Front Image

Back Image

Box Front

Box Inside