Glossary
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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.