After installing the Arduino PS/2 mouse and the Mouse and Keyboard libraries he wrote some code (see his Instructables page).

I prefer USB mice but I had that one issue where the PC didn't activate the USB ports and I needed to mouse around. I keep a PS/2 adapter around in case that happens again.

The PS/2 protocol is a bit strange as the peripheral sets the clock. Since PS/2 is a bidirectional protocol, the mouse also accepts commands.

As topic says, I just ordered a PS/2 mouse, and now discover my Asus P5K only has a PS/2 Keyboard port. :/ Will that work, or do I need to purchase an USB adapter? [image of port] It is just ...

Raymond Chen, a developer at Microsoft, explains how an adapter that converts a USB Type-A terminal, which was once included with some mice and keyboards, into a PS/2 connector works.