IBM 1PA, Руководство по эксплуатации, установке и обслуживанию

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connectivity. The capacity of a system or device to be
attached to other systems or devices without
modification. (T)
D
daisy chain. A method of device interconnection for
twinax 5250 devices that allows serial connection of the
devices. In this scheme, the last device should be
terminated.
data stream. The sequence of characters being
transmitted over a line.
device. The generic term for a piece of equipment or a
mechanism; for example, the PC display or the PC
attached printer.
differential mode noise. High-frequency signals that
travel in the data path. Differential mode noise is
induced by attached devices, incorrectly terminated
cables, and the conversion of common mode noise
signals. To suppress this type of interference,
differential filtering and correct cable termination are
required.
drop cable. The cable that connects a data station to
a trunk coupling unit. Synonymous with stub cable. (T)
F
FTP. Foiled twisted-pair. This is a shielded version of
UTP (unshielded twisted pair) cable and can provide
improved noise immunity for the network.
H
host system. (1) A data processing system used to
prepare programs and operating environments for use
on another computer or controller. (2) The data
processing system to which a network is connected and
with which the system can communicate. (3) The
controlling or highest level system in a data
communication configuration; for example, a System/38
is the host system for the workstations connected to it.
hot-swappable. The ability to remove and install
devices in a powered up system unit without powering
off the unit and without causing interruption on the other
modules that are already installed in the hub chassis.
I
Initial Program Load (IPL). (1) The initialization
procedure that causes an operating system to
commence operation. (2) The process by which a
configuration image is loaded into storage at the
beginning of a work day or after a system malfunction.
(3) The process of loading system programs and
preparing a system to run jobs. (4) Synonymous with
system restart, system startup.
insulation. A non-conducting material that insulates
electrical parts from each other.
J
jitter. (1) Short-term non-cumulative variations of the
significant instants of a digital signal from their ideal
positions in time; for example, phase jitter, pulse
duration jitter. (T) (2) Undesirable variations of a
transmitted digital signal.
Light-emitting diode (LED). A semiconductor chip
that gives off visible or infrared light when activated.
L
line. The cable from the host computer or controller to
which one or more workstations are attached.
local workstation. A workstation that is attached
directly to the host system with twinaxial cable.
M
modular jack. A connecting point for UTP cabling. In
the case of the 7299, these can be either RJ11 or RJ45
types.
N
noise. A disturbance that affects a signal and that can
distort the information carried by the signal. (T)
noise signal. Signals that interfere with the primary
signal on a data run. This interference typically results
in errors that cause down time. A noise signal can be
induced environmentally or through low-grade UTP
components.
G-2
Planning, Installation, and Maintenance Guide