Glossary

Control Character

Any character assigned as ASCII numeric code less than the SPACE character. These characters are used to initiate a control function on the receiving device. Also a symbol you can create by pressing one of your computer’s keys while holding down the Control key. These symbols are not usually printed, and are generally used to control screen formatting and cursor positioning.

CPU

Central Processing Unit. The computer hardware which processes software instructions to control the computer system and its peripherals.

CRT

Cathode Ray Tube. This term is commonly used to stand for the video display terminal.

CTS

An acronym for Clear To Send. This signal is generated by a modem in response to RTS to indicate that a communications channel has been established and that data can be sent.

Cyclic Redundancy Check

An error-detection technique in which a data validation value is mathematically derived from a block of data and transmitted at the end of the block. The receiving end recomputes the value and if it matches the value sent, the data is assumed to be valid (error-free). If not, the receiver notifies the transmitter that an error has occurred and the block is retransmitted.

D

Data

Any type of information, such as numbers, letters and symbols, that can be processed by a computer.

Database

A source or collection of information. In the context of communications, a dialup service from which users can exchange or retrieve information.

Data Bits

The actual characters being transmitted between two computers when asynchronous communications is being used. Usually 7 or 8 data bits are used.

Data Communications

A broad term covering any exchange of information between computers or similar systems over telephone lines.

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