There's numerous ways to achieve the task of a "computer mouse", with the design I described yesterday being quite outdated. So what are the common designs today?
Most mice (or wireless "hamsters", lol!) shine a laser light askew at a surface to reveal any roughness it might have. An image sensor rapidly compares the last 2 frames to determine how far the previous has to be shifted to match the next.
Involves a lot of very clever arithmetic, & a "digital signal processor" to run it on!
