The Mouse (continued)

Types of Mice
There are basically three different types of mice: mechanical, optomechanical and optical.

The mechanical mouse has a small hard rubber ball underneath that moves against two rollers as it's passed across a flat surface. Mechanical sensors detect the movement of the rollers as an 'x' and 'y' axis and the cursor on screen is moved accordingly.

An optomechanical mouse works on the same principal. The rollers have wheels on the end of them with evenly spaced holes. As the wheels spin, a light-sensitive optical device counts the number of holes that pass by and convert those numbers to an 'x' and 'y' axis.

An optical mouse is more accurate or precise and has no moving parts. It uses a laser to detect movement and has to be paired with a special pad or mat that has an embedded optical reference grid.

Mouse Connections
The serial mouse is, by far, the most popular and the easiest to install. They connect to an RS-232C serial port; one of the COM ports on the back of the computer (a DB-9 or a DB-25 male connector). A serial port is an interface that transmits one bit at a time, and RS-232C is a standard that most serial ports conform to. The fact that they do take up a COM port (and it's respective IRQ) is the biggest problem with the serial mouse. Personal Computers are very limited to the number of COM ports available.

The bus mouse was originally developed to help alleviate the problem of the COM port shortage. It connects to the computer through a small round connector (female mini-DIN-9) on the back of an expansion card installed on the motherboard. Because an expansion card had to be configured and installed on the motherboard, these mice were considered much more difficult to install. Now they are pretty well obsolete. They did free up a COM port, but they still took up an IRQ as well as an expansion slot.

The PS/2 mouse seems to be the answer to both problems. It's a type of serial mouse but it connects to a PS/2 connector (female mini-DIN-6) that is hard-wired directly to IRQ 12. It installs as simply as any serial mouse, doesn't use up a COM port, and needs no expansion card installed. Not only that, but it uses a fairly obscure IRQ that was mostly unavailable to other devices.

A cordless mouse uses infrared technology to do away with the cord. It seems like it would be a good idea because the cord on a mouse can be a real pain. It drags across the top of the desk, gets caught and hangs up in the other cords, or anything that might be lying on your desktop. They also have a receptor that must be visible to the mouse (line of sight), if anything is in the way, the mouse won't respond. This can sometimes cause a little aggrivation unless you keep a very tidy desk. Cordless mice are more expensive than other types.

The USB mouse is, by far, my favorite. With Windows98, USB has become one of the most advanced (and one of the best) connections around for mice, printers and other peripherals. Installation is simple. It's hot-swappable, so you can plug it in even when your computer is running. The mouse is immediately recognized and you can use it right away.

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