Glossary

Packet Switched Network

System where messages are transmitted in packets, each individually addressed and routed through the network.

Packetised Ensemble Protocol (PEP)

A patented data transmission technique used by the TrailBlazer modem to transmit data at up 18000 bps on the switched telephone network.

Parity

A simple method of error checking by which the number of data bits received are added together to ensure that the correct number have been received. Most bulletin boards do not use any parity checking.

Password

A second-level security device, generally being a set number of characters. The length and types of passwords used with bulletin boards varies from one system to another. On most videotex systems a four character password is used. See also ID Number.

PBX

See PABX.

PEP

See Packetised Ensemble Protocol.

Peripheral

(Or peripheral device). A device, such as a video monitor, disk drive, printer or modem, used in conjunction with a computer. Often (but not necessarily) physically separate from the computer and connected to it by wires, cables or some other form of interface.

Phase Modulation (PM)

A method of modulating the carrier wave based on the data by varying the phase relationship of the signal elements.

Point-to-point

A connection between two points as opposed to a multipoint or multidrop line.

Port

The point of connection, usually a physical connector, between a computer and a peripheral device, another computer or a network.

Private Line

See Leased Line.

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