Mike's PCjr Page

I recently got several PCjr items from CR and among them was an cable for which I can't figure out the purpose...

This appears to be a cable for a Mouse Systems PCjr mouse. One plug goes into the light pen port to get power, one plug goes into the serial port, and the little black plug (barely visible in the photo) plugs in on the inside of the mouse.

I think you could use this to convert a regular Mouse Systems M2-generation mouse to a more convenient PCjr form. Connecting a regular M2 mouse to a PCjr is a bit cumbersome:

• It requires using a PCjr serial port adapter.
• M2 mice need external power from a wall wart.

Switching the mouse to this cable would address both of those issues.

Later generations of Mouse Systems mice (such as the M4) pulled power from the serial port and didn’t need an external power adapter.

Wow, thanks for the info. I'm going to be on the lookout for a Mouse System mouse now...