Our relationship with modern optical mice usually follows one of two paths: either we look for an ultra-high-end option with an incredible amount of DPI and a polling rate that's scary, or we use the model made of chinesium that came in the kit with the computer until it melts in our hands. However, the optical mouse has a much more interesting history than we think, going back to the early '80s, with the first commercially available model for the PC: Mouse Systems PC Mouse. Shelby from the Tech Tangents channel managed to get one in near-perfect condition, and decided to put it to the test…
A quick search on the web indicates that the concept of the optical mouse had two parallel origins. The first mentions Richard F. Lyon and the company Xerox, with a design based on an image sensor and an integrated motion detector, exclusive to Xerox STAR systems.
The second tells us about Steve Kirsch from MIT and Mouse Systems Corporation, who besides creating a version compatible with Sun workstations, also adapted it for use in PCs and clones. This "Mouse Systems PC Mouse" is a very special peripheral, and Shelby from Tech Tangents managed to get one almost in "New Old Stock" condition.
Exploring the first commercial optical mouse for PC
One of the first things we must assimilate about the Mouse Systems PC Mouse is that the pad is as important as the mouse. Shelby got carried away by emotion and decided to open the mouse before testing it, but it was definitely worth it. Inside there are two mirrors, one for each optical sensor, with a total of eight photoreceptor cells that register X/Y movement. This in turn requires two LEDs, one red and the other infrared. Finally, the pad acts as a third "mirror", with a blue and black grid to identify the axes.
As we move the mouse, two of the photoreceptors in each sensor are "covered", while the other two remain "exposed", and that difference is what allows converting up/down and left/right into a real position for the pointer. Now, this reveals a problem: The mouse is not very tolerant to changes in its angle, and requires some discipline from the user. The other essential piece for the PC Mouse configuration is the controller card. Besides coordinating all the logical aspect, this card is responsible for providing 5 volts to the mouse, using a 7805.
The software is equally fabulous: Traditionally, the user must configure jumpers before installing the card, and is obliged to follow a trial-and-error process to avoid conflicts. However, the PC Mouse driver asks a series of questions, and presents an appropriate configuration in advance. Now "appropriate" doesn't mean perfect, and in case of an error, the user can run a test program. Fortunately, nothing strange happened with Shelby's mouse, and even the emulated mode as a "Microsoft mouse" worked perfectly.
The last phase of the video focuses on compatibility with various programs, and all responded positively, better than expected knowing that it's an accessory with 40 years on its shoulders.
(Editor's note: The design is from 1982, but the unit Shelby has was manufactured in 1986.)
