I was testing old Amiga computer and noticed, that somewhere I lost the mouse. It is proprietary mouse for Amiga computer, it even does not work with Atari ones. The mouse itself is very simple- only raw quadrature information is sent (mouse buttons are on separate wires). This make mouse very simple, but it uses 8 wire cable! (9 with middle button).
I was thinking, that I might find some ball mouse for PC computer, remove controller and will build exact replica of the Amiga mouse. But ball mouses are rare. Instead I found several optical mouses, the old ones, with two chips inside.
The first mouse was USB one, with Avago chip:
The chip is ADNS-5020, from Avago.
This chip has SPI interface, too modern for our goals.
Next mouse was PS2 one:
This chip is older, OM02, from unknow company in China.
This chip is perfect- it has quadrature (delta X and delta Y) output pin. Datasheet even describes how to build your own mouse.
For Amiga mouse there is no need to build anything. Solder out controller, connect quadrature pins to cable. Rewire mouse buttons (if you need. Mines was connecting to Vcc, Amiga needs connection to GND).
The only problem is thick wire. But mouse works very well.