History of the computer mouse

It used to be that when you wanted to navigate a computer screen, you had to use keyboard arrow keys or complex text commands. That is until the revolutionary computer mouse squeaked into popular consciousness in 1984.

The first movable mice were mechanical. Invented in 1972 at Xerox’s Palo Alto Research Center (PARC) by a researcher called Bill English, the mouse’s main feature was a rubbercovered tracking ball that was able to move in all directions. It rolled around underneath the device’s body as users moved the mouse across a flat surface.

Two rollers inside rubbed against the side of the ball and picked up the speed and direction of the movements. These were connected to tiny perforated discs, lit by light-emitting diodes (LEDs). The resulting flashes of light gave direct feedback on the rotation direction and speed, and were sent to a tiny onboard integrated circuit (IC). This converted the information into binary data the computer could understand that was zapped down the connecting wire. A software-driven cursor moved exactly to the desired position on the screen. Simple yet efficient – as long as you cleaned it regularly to keep all the moving parts rolling smoothly.

Today, the mechanical mouse has almost died out. Most people use an optical mouse with no moving bits inside. So it doesn’t need cleaning or maintenance.

Instead of a tracking ball, the optical mouse uses a small LED, most often red, and a tiny complementary metal-oxide semiconductor sensor – a sort of microcamera. The images captured are passed on to a digital signal processor (DSP) which compares the images and detects changing patterns of movement. Then, as before, an on-board IC turns the information into binary data to be sent to the computer, with updates hundreds of times every second. This gives fast, smooth cursor movement on the screen.

The latest laser mice – using an infrared laser diode instead of LED – work much the same way but deliver up to 20 times the performance of an optical mouse, and use less power too. There’s one major drawback, though. They sometimes have trouble tracking on reflective surfaces, which confuse the sensors.

But can you imagine going back to the bad old days of scraping stuff from your tracking ball?