IBM 1PA, Operational, Installation, And Maintenance Manual

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auxiliary storage within the system unit, depending on
the model. It also contains a diskette magazine drive
and an optional tape drive for offline storage.
System/36 allows both local and remote attachment of
display stations and printers and supports several
communications protocols.
System/38. A general purpose data processing system
for interactive and batch processing. The system has
several models that vary in the size of main storage and
auxiliary storage within the system unit, depending on
the model. It also contains a diskette magazine drive
and an optional tape drive for offline storage.
System/38 allows both local and remote attachment of
display stations and printers and supports several
communications protocols.
T
terminated line. A telecommunication line with a
resistance attached across its far end equal to the
characteristic impedance of the line, so that no
reflection and no standing waves are present when a
signal is placed on it at the near end. Contrast with
bridge tap.
terminator. A device used to terminate a transmission
line.
transmission. The sending out of data signals to be
used by the receiving unit.
twinax breakout box. Receives a DB25 pin connector
from the host unit and breaks out the signals into 8
twinax connectors, using one connector for each port.
twinax cable. A cable consisting of two conductors,
usually small copper tubes or wires insulated from each
other, within and insulated from another conductor of
larger diameter, usually copper tubing or copper braid.
twinaxial protocol. In this manual, the data
communication protocol and signal levels that can be
transmitted over twinaxial, shielded-pair, or unshielded
twisted-pair cabling media.
twisted pair. A transmission medium that consists of
two insulated electrical conductors twisted together to
reduce noise. (T)
U
unbalanced (to ground). The state of impedance on
a two-wire line when the impedance to ground as
measured from one wire is different from the impedance
to ground as measured from the other wire. Contrast
with
balanced (to ground).
UTP. Unshielded twisted pair
UTP data signal. A differential signal. The data is
extracted by subtracting the signal on one leg of the
UTP from the signal on the other leg of the same pair.
W
wiring closet. A room that contains one or more
equipment racks and distribution panels that are used to
connect cables.
workstation. (1) A functional unit at which a user
works. A workstation often has some processing
capability. (T) (2) One or more programmable or
nonprogrammable devices that allow a user to do work.
(3) A terminal or microcomputer, usually one that is
connected to a mainframe or to a network, at which a
user can perform applications.
workstation controller (WSC). (1) A device that
provides for a direct connection of local workstations to
the system. (2) In the AS/400 system, an I/O controller
card in the card enclosure that provides the direct
connection of local workstations to the system.
workstation line. The cable from a host computer or
the chain of workstations to which a workstation is
connected.
G-4
Planning, Installation, and Maintenance Guide