Dec 5, 2019
The computer mouse is one of the most ubiquitous devices in the world. It's the primary way we interact with computers. And it's also one of the longest lived computing devices. Since its invention in the early 1960s the overall design of the computer mouse has changed very little. That being said, there has been incremental improvement to the mouse's internals.
The earliest mouse was developed by Doug Engelbart and Bill English at the Augmentation Research Lab at Stanford. Right off the bat, the mouse looks reasonably similar to what we are familiar with today: a puck that fits in the hand with buttons(or in this case a single button) on top. However, under the hood we have a rodent of a totally different species. The ARC mouse was actually an analog device: it used two perpendicular wheels connected to potentiometers to measure it's movement across a desk.
The next update to the mouse came in 1973 at Xerox with the invention of the ball mouse. This new mouse was designed to be used with the Alto, the first GUI-based computer. The largest external change is the fact that this new Xerox mouse uses a single large ball instead of two perpendicular wheels. The other change was a little more hidden, the new Alto mouse was entirely digital. Instead of using potentiometer to measure movement this new mouse used a set of encoding drums and brushes. The surface of each drum alternated between stripes of conductive and nonconductive material. As the drum spun it would alternate between closing and breaking a circuit with the brush, thus creating a stream of binary data.
The final big change, which would become the most popular design, happened in 1980. This new mouse would be built for the Apple Lisa by Hovey-Kelley Design, an industrial design contractor. On the outside is the same familiar mouse, it even glides over a single ball like the earlier Xerox mouse. There were some changes made to make it a more marketable product, a lot of the design of the Lisa mouse came down to making it cost under $35 to produce. However, the largest change was in how it measured movement: the new mouse used slotted encoder disks and optical pickups instead of drums and brushes. These encoder disks are simply plastic wheels with a pattern of slots cut along there edge, as they spin the disk alternated between blocking and letting light through from an infrared source. The light pattern is then read off by an infrared detector on the other side of the disk. The operating principal is the same as the earlier Xerox mouse but the device is much more durable since there is no contact between the encoding disk and the pickups.
If you want to learn more about the history of the mouse, listen to my episode on the matter: