Hardware engineers solve a usability problem with the PS/2 connector, but inadvertently create a new one

Raymond Chen

The PS/2 connector was used for both keyboards and mice. The connectors were physically identical, but the protocols were different, so every computer had a label next to each PS/2 port indicating whether it is a keyboard port or a mouse port. By convention, the keyboard plug and port were purple, and the mouse plug and port were green. These connectors are not seen much nowadays, having been largely displaced by USB.

During a group reminiscence of earlier days of computing, one of my colleagues recalled a story from his time at a company that manufactured PCs: One of their hardware engineers had come up with a clever way to detect whether it was a mouse or keyboard that was plugged into the PS/2 port. That way, the user could plug the mouse and keyboard into either port, and the system would be able to figure out which was which.

The company shipped a system with this feature, leaving two unlabeled PS/2 ports and allowing users to plug their mouse and keyboard into whichever port they liked. “Our computers are so easy to use: Just plug it in wherever it fits, and it just works!”

Unfortunately, the company also was inundated with support calls from customers asking how to set up their PC, since there were no labels to tell you where the mouse and keyboard go. This was no doubt documented in the Quick Start guide, but as we all know, nobody reads those things.¹

Their ease-of-use feature turned out to be a support call generator.

They quickly modified their case design so that the two ports were labeled with mouse and keyboard icons, but the hardware secretly didn’t care.

Related: Microsoft invented a design that allows cylindrical batteries to be inserted in either orientation.

¹ I read those things.