dan wrote:
Devonshire wrote:

Dammit!!! You got me! I just realized that the
old ball mice are optical as well.
I couldn't see the forest for the trees

Devonshire


No, they were roller driven (unless inside there were optical sensors to
check the rotation of the rollers).

Most of the ball stuff I pull apart, the roller drives a shutter system
that interrupts a light beam.