This is a very simple PS/2 to serial mouse protocol converter which uses a PIC micro-controller and a MAX232.

Two schematics are presented for two different PIC micros. It should be trivial to port this application to any other PIC micro-controller since they all share similar peripherals.

First install gputils for gpasm and Pickle for ICSP (if you are using a Velleman K8048 for example).

PC Pointer needs some support files from Pickle so we install those first.

hg clone http://hg.kewl.org/pub/pickles
cd pickles
make
make install
cd ..

Now we can fetch PC Pointer and and assemble the code.

hg clone http://hg.kewl.org/pub/PCPointer
cd PCPointer
make

The resultant hex file is used to program the chip. Here I use Pickle and I have targeted the 16f688.

p14 program pic16f688.hex

Plug an old PS/2 mouse or newer USB mouse with PS/2 support into the input port of the circuit. Connect the serial output into the RS232 input of your old computer.

Boot into DOS and detect the mouse with MOUSE.COM 8.20.

MOUSE.COM /C1

Disable it like this.

MOUSE.COM OFF

Windows 95 should auto-detect the device as a generic serial mouse.

PS/2 protocol