Glossary

BIOS Basic Input/Output Services. This is the software that initially runs when you first power up the computer, and tells it how to interact with the outside world through the keyboard, mouse, and so on.

Bit Binary Digit. The smallest amount of information that a computer knows about. A bit is represented as a 1 or a 0, representing the states on or off.

bps Bits per second. Used as an expression of data rate, or how fast data can be sent over a connection.

Byte The smallest unit of directly addressable information. A byte consists of eight bits. A single byte represents one alphanumeric character. The term probably originated as a pun on the premise that a collection of bits is a bite, or byte. Another term derived from this pun is the very rarely used unit the nibble, which is four bits, or only half a byte.

CAD Computer Aided Drafting. This defines a type of program used primarily for architectural drafting purposes, such as architectural drawings and blueprints.

CD Compact Disk. A plastic disk capable of writing and reading data through a laser. A CD is commonly used for music and information, and can hold about 600 MB per disk.

CPU Central Processing Unit. This is the "brain" of the computer, the part that actually performs mathematical calculations on data presented to it.

DSL Digital Subscriber Line. Broadband method of connecting to an ISP over a conventional telephone line.

DVD Digital Versatile Disk. Originally was called Digital Video Disk, as its original (and still primary) function was for movies and videos, but was later changed when manufacturers realized its potential as a method of distributing and archiving programs and data. The DVD is a plastic disk that uses a laser to read and write data from it. A DVD is capable of holding between 2 GB and 4 GB of data, depending on the method used.

GB Gigabyte. Technically, a gigabyte is 1,024 megabytes, or 1,073,741,824 bytes. Common usage has rounded this to one billion bytes.

ISP Internet Service Provider. A generic term for any business that provides the services to enable customers to connect to the Internet.

KB Kilobyte. Technically, a kilobyte consists of 2¹⁰ bytes, or 1,024 bytes, even though the prefix kilo normally denotes one thousand of something. Common usage has rounded this to one thousand bytes.

MB Megabyte. Technically, a megabyte is 2²⁰ bytes, or 1,048,576 bytes. Common usage has rounded this to one million bytes.

Modem Modulate - Demodulate. Refers to a modem's function of converting a digital signal to an analog signal, and back again.

NIC Network Interface Card. Provides the actual plug-in receptacle on a computer that connects it to a network. May be an actual card that fits into a motherboard expansion slot, or a chip with a receptacle mounted on the motherboard.

RAM Random Access Memory. A method of storing temporary information shortly before and after the CPU needs it to perform calculations.

ROM Read Only Memory. A method of storing information that the computer requires when it is first powered.

TB Terabyte. Technically, a terabyte is 1,024 gigabytes, or 1,099,511,627,776 bytes. Common usage has rounded this to one trillion bytes.

USB Universal Serial Bus. A method of connecting other peripheral devices to a computer.

VAC Volts Alternating Current. A method of describing electrical current. Household current in the United States is measured in VAC.

VDC Volts Direct Current. Many electrical appliances use direct current.

W Watts. A method of describing electrical power.