Peripheral

An external device, such as a printer or modem, connected to a computer.

Port

An input/output socket on a computer to which you can connect a peripheral.

Power-on diagnostics

A set of self-testing routines performed automatically by the computer every time you turn it on. See Appendix C.

Program

A disk file that contains coded instructions telling the computer what to do and how to do it.

Prompt

A message displayed on the screen that tells you what action you need to perform next.

RAM

Random Access Memory. The portion of the computer’s memory used to run programs and store data while you work. All data stored in RAM is erased when you turn off the computer, so you must store any data you want to save on a diskette or hard disk.

Read

To copy data from one area to another. For example, when you open a text file stored on disk, the computer reads the data from the disk and displays it on the screen.

Read/write head

The physical device inside a disk drive that reads and records data on the magnetic surface of a disk.

Real-time clock

A battery-powered clock in the computer that keeps track of the current time and date even when the computer’s power is turned off.

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