Mark II X063X
Jack Hawley's design, with drum encoders and a demanding cleaning procedure.
This mouse was designed entirely by Jack Hawley, a Xerox designer and the author of several mouse patents.
The positioning mechanism is an early drum-shaped contact encoder. Later models replaced the drum with a disc to save space.
There are two pairs of feelers, one short and one long. A bridge on the drum closes the first pair sooner when turning one way, and the other pair sooner when turning the other way. That is how the mouse detects direction.
To remove the ball for cleaning, you had to dismantle the entire mouse. I have no idea what the thinking was there.
The design is a brick aimed at engineers, but there were plenty of variations in case and button colours.
As a bonus, a clearance-sale advert =)
