With technology changing so quickly, it's a wonder our computers don't become obsolete a month after we buy them. Without a way to expand a computer's capabilities, the world would quickly fill up with oversize paperweights and doorstops.
Thank heaven for the far-thinking propeller-heads who dreamed up internal expansion slots -- the ubiquitous feature on personal computers that helps keep the world safe from massive silicon junk piles.
Most desktop varieties of IBM-compatible and Macintosh computers have at least one expansion slot -- a thin strip that locks an expansion card in place on the motherboard inside your computer. These expansion cards add functions that you might not have been able to use before, including things like sound, a fax-modem, high-resolution graphics or connections to local area networks.
Macintosh computers have traditionally sported NuBus adapter slots, while pc's include PCI Card slots. Portable and laptop computers commonly use PCMCIA or PC cards. Desktop PCs use PCI, AGP, and IDE bus adapter slots.
Why are there all these different names for connectors that basically do the same thing? Not only does the underlying technology vary among different types of expansion slots, the cards that fit in each type are different in size and shape as well. That means a network adapter card for a PC will only work in a PC -- not a Macintosh or a portable computer. Even the number of pins (those gold or silver lines you find on the connecting end of expansion cards) are different.
PC Cards are about the size of a credit card and are encased in a plastic or metal covering. The connecting pins usually peek out from the bottom of the card. Typically, these cards slide into openings on the sides of laptops, eliminating the need to open the computer, as is necessary with many other types of expansion cards.
NuBus adapter cards, which are used for Macintosh computers, are often long, thin circuit boards with plastic guides covering the connection pins. PCI and AGP cards, which plug into PC-compatible computers, can appear similar to NuBus adapter cards. However, instead of a plastic guide covering the connecting pins, they usually have flat gold- or silver-colored connecting pins.
Most expansion slots can handle a wide variety of expansion cards: For example, the slot that works for a network card may also work for a modem card. Only older computer models (and some laptops) have certain slots for specific types of cards, with the exception of AGP slots and PCI express slots. You can find anywhere from one to 5 expansion slots in a standard desktop computer.
Found in IBM-compatible desktop computers.
IDE slots are used to connect hard disk drives and CD-ROM drives. They can be used to connect up to two different devices on each expansion slot, providing a low-cost way to add additional drives without needing another expansion card. All that is required is a cable.
Found in IBM PS/2 Desktop computers.
MicroChannel slots are used to connect network cards, modems, additional memory cards and video cards, and provide specialized connections to peripheral devices. MicroChannel slots are no longer used in newer IBM computer models.
Found in Macintosh computers.
 NuBus slots are used to connect many kinds of expansion cards, including network adapter cards, video cards, additional cache cards and PC computer expansion cards.
 Found all IBM-compatible desktop computers and Macintosh computers.
PCI is a standard bus adapter that allows high-speed connections to most peripheral devices, including video adapter cards, network cards, cache cards and PC computer expansion cards.
Found in laptop computers.
PC Cards conform to standards created by Personal Computer Memory Card International Association. These cards house modems, NIC cards, usb expansion cards, wireless cards or hard disk drives connectors. .
SCSI -
 Found on desktop computers, predominantly in Macintoshes.
SCSI expansion slots allow you to connect a wide variety of devices like CD-ROM drives, printers and scanners. You can connect up to six different SCSI devices in a chain. |