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How Does a Computer Mouse Work?

How Does a Computer Mouse Work?

To many people, computer mice have become as familiar as television remote controls. But you might be interested in knowing just how that little blob of molded plastic transmits your wishes to the computer.
Techspirited Staff
By Gary Orlando
CEO, Tech Services
The public first saw a computer mouse when it was attached to the Macintosh computer in 1984. The Mac and its accompanying mouse had their debut at the half-time show of the Superbowl. A few years prior to this event, Steve Jobs, co-founder of Apple Computer, was allowed to visit and tour Xerox's research (PARC) facility in California, and noticed this funny-looking thing that was used to move the cursor around the screen of a computer. This was a revolutionary idea, since prior to this the keyboard arrow keys were the only way to navigate a computer screen. Jobs 'borrowed' the idea, and designed his own mouse to accompany the unveiling of his new Macintosh to the public. Then Microsoft picked up on it when they released their version of a graphical user interface (Windows) to make things even easier, and the rest, as they say, is history. The first types of mice were mostly mechanical, a ball rolled around under the body of the mouse, and rollers sensed the direction and speed at which the mouse was moved. The rollers were connected to a disc that contained holes and used an IR LED (Light Emitting Diode) to sense the movement. Two sensors per wheel gave both speed and directional information to an on-board integrated circuit that decoded this data and transmitted it to the computer. All in all, a very good low-cost device that was dependable as long as the roller ball was kept clean. The only problem was having to remember to clean the ball and the three roller assemblies, to keep the mouse rolling freely. This became a necessity especially when you ate at the computer.
As usual with technology, designers and engineers studied the design and decided that improvements and updates were necessary. The next series of mice were developed by Agilent, and they use a sensor similar to an LED to actually translate the movement of the mouse to an on-board integrated circuit. The LED sends out signals that are bounced off the surface. This data is then transmitted to a DSP (Digital Signal Processor) chip that decodes the information and sends it along to the computer. Since the LED and DSP devices are all electronic, the data sensing and conversion takes place at a rapid pace and a very precise mapping of the area can be generated, which translates into a very smooth movement of the cursor. All modern operating systems can take advantage of this technology by offering many more options when it comes to customizing your mouse, most notably tracking and speed modifications. The optical mouse can work on most flat surfaces and rarely requires a mouse pad. Since everything is electronic and optical there are no moving parts on the surface, no internal components to clean regularly, and we can go back to eating chips and dip by the computer.
Taking this idea one step farther, Logitech now offers both cordless mice and keyboards. The mice work exactly the same way, only they do not have any type of cord to tether them to the computer. They contain rechargeable batteries and in the evening when you are finished with your computer session you just place the mouse in the supplied cradle to recharge the batteries, and you're ready for the next day. Another advance with the modern optical mice is the inclusion of more buttons; most notable are the side buttons used for forward/backward in browser environment and also in the Windows XP series of operating systems. The rolling wheel between the left and right standard mouse buttons introduced by Microsoft several years ago for scrolling up and down on the screen is another very useful feature in the ever-changing computer mouse as it continues to evolve. Who knows where we are headed with the evolution of the mouse? Perhaps the next thing to come along will be a mouse-like device that is no longer constrained to the desk top and will instead be held in the hand, for full 3-dimensional movement. Combine that with voice-recognition software and you'll be able to lean back in your recliner, close your eyes, and write that best-selling memoir you've been planning. Isn't technology terrific?