IBM 8237 Installation And User Manual Download

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Glossary of Terms and Abbreviations

X-5

SDLC procedures. Each frame begins and ends with a
flag.

ft. (1) Foot. (2) Feet.

FTP. (1) File Transfer Protocol. (2) Foiled twisted pair.

FRU. Field replaceable unit.

fully qualified path name. In an operating system, a
file name that includes all directories and the drive in
the hierarchical sequence above the file.

function. (1) A specific purpose of an entity, or its
characteristic action. (A) (2) In data communications, a
machine action such as carriage return or line feed.

functional unit. An entity of hardware, software, or
both, capable of accomplishing a specified purpose. (I)
(A)

gateway. A device and its associated software that
interconnect networks or systems of different
architectures. The connection is usually made above
the reference model network layer. For example, a
gateway allows LANs access to System/370 host
computers. Contrast with

bridge and router.

group. (1) A set of related records that have the same
value for a particular field in all records. (2) A collection
of users who can share access authorities for protected
resources. (3) A list of names that are known together
by a single name.

hardware. Physical equipment as opposed to
programs, procedures, rules, and associated
documentation. (I) (A)

header. The portion of a message that contains
control information for the message such as one or
more destination fields, name of the originating station,
input sequence number, character string indicating the
type of message, and priority level for the message.

hertz (Hz). A unit of frequency equal to one cycle per
second.
Note: In the United States, line frequency is 60 Hz or a
change in voltage polarity 120 times per second; in
Europe, line frequency is 50 Hz or a change in voltage
polarity 100 times per second.

hop. See

repeater hop.

HMI. Hub Management Interface.

hub. In a network, a point at which circuits are either
connected or switched. For example, in a star network,
the central node, or in a star/ring network, the location
of wiring concentrators.

Hz. Hertz.

IEC. International Electrotechnical Commission.

IEEE. Institute of Electrical and Electronics Engineers.

in. Inch.

in-band. A communication data stream transmitted
within the primary signaling channel or frequency band.

input/output (I/O). (1) Pertaining to a device whose
parts can perform an input process and an output
process at the same time. (I) (2) Pertaining to a
functional unit or channel involved in an input process,
output process, or both, concurrently or not, and to the
data involved in such a process.

interface. (1) A shared boundary between two
functional units, defined by functional characteristics,
common physical interconnection characteristics, signal
characteristics, and other characteristics as
appropriate. (I) (2) A shared boundary. An interface
may be a hardware component to link two devices or a
portion of storage or registers accessed by two or more
computer programs. (A) (3) Hardware, software, or
both, that links systems, programs, or devices.

interrupt. (1) A suspension of a process, such as
execution of a computer program caused by an
external event, and performed in such a way that the
process can be resumed. (A) (2) An instruction that
directs the microprocessor to suspend what it is doing
and run a specified routine. When the routine is
complete, the microprocessor resumes its original
work.

IP. Internet Protocol.

IPX. Internetwork Packet Exchange.

IPX socket. Within a device attached to an IPX
network, the address of a process, such as file service
or diagnostics.

ISO. International Organization for Standardization.

jabbering. A condition in which a device is
transmitting a frame that is longer than the maximum
allowed length.

jack. A connecting device to which a wire or wires of a
circuit may be attached and which is arranged for
insertion of a plug.

kg. Kilogram.