The Nimbus PC-186 used a protocol called quadrature for the mouse control.
This was a precursor to the serial and usb mouse that became the norm.
The original mouse is difficult to locate and are generally quite tired after 30 years
Here I have created an interface that allows a standard PS/2 mouse to control the Nimbus.
It uses an Arduino Nano and is powered from the Nimbus Mouse port.
Quadrature used a collection of 4 sensors, 2 for each axis
The process used a slotted wheel with optical sensors(a transmitter and a reciever) 90degrees out of phase.
Using a binary signal, the direction could be sensed depending on which channel was leading.
We need to mimic this signal using the serial data feed from a PS/2 Mouse
The project uses an Arduino Nano and the HEX file can be downloaded from HERE
Any PS/2 mouse can then be used with the Nimbus!
The inside of the box is potted to hold all the connections to the socket secure and give it a nice finish.
The Nano is socketed and can be removed for simple replacement or programmed in situe using USB