Hard disk

The enclosed unit used to store data permanently. Unlike a diskette, it is fixed in place. It can process data more rapidly and store many more files than a diskette.

Hardware

Any physical component of a computer system, such as a monitor, printer, keyboard, or CPU.

Hexadecimal

A base 16 numbering system frequently used by programmers. Any decimal number between 0 and 255 can be represented by a two-digit hexadecimal number.

High-density

A type of diskette format that allows you to store more data than normal. A 5¼-inch high-density diskette can store 1.2MB of data. A 3½-inch high-density diskette can store 1.44MB of data.

Input/output (I/O) port

See Port.

Interface

A physical or software connection used to transmit data between equipment or programs.

Internal command

An MS-DOS command that is stored in the command processor of the operating system; it is not a separate program file. This means that you can execute an internal command without specifying a pathname. Examples include COPY, DEL, RENAME, and DIR, among others. Unlike external commands, internal commands can be executed from any drive or directory.

Jumper

A small device that fits over two small pins on a circuit board to activate a particular function.

Keyboard

A device resembling a typewriter keyboard to enter letters and numbers to the computer.

8 Glossary