Help with plugs on an old beige Mac G3

Factual Questions
1

I pulled my first computer, a beige Macintosh G3 out of storage today. It booted up great. My problem is, I can’t remember how to hook up the mouse AND the keyboard.

There is one plug-in hole that accepts the plug that is round with one flat side which comes directly out of the Mac keyboard. Looking down into the plug you see 4 tiny pins, two on each side and a rectangular black piece at the bottom (or top, depending on how you hold it). If I plug this into the plug-in hole, the keyboard works.

The problem is, the mouse I have is not the original Macintosh mouse and it has the exact same plug as the keyboard. But there is only one plug-in hole shaped like that on the back of the computer. The mouse works great if I unplug the keyboard from that one plug-in and plug in the mouse there.

I know these parts worked together in the past, but I can’t figure it out. There is just no other place to plug in the mouse (once the keyboard plug-in hole is filled).

Any old Mac experts out there with an idea?

2

ADB is the plug you describe. Usually there’s an ADB port on the keyboard itself which you can plug the mouse into.

3

There are two ADB ports on the keyboard - one on each side.

4

Yep. You guys got it. There is a plug cleverly hidden on the underside of the keyboard. Thank you.