IBM 3174 Introduction Manual page 75

of the data to any unauthorized recipient. Contrast with
decrypt.
extended binary-coded decimal interchange code
(EBCDIC). A coded character set of 256 eight-bit
characters.
F
field. See display field.
file. A named set of records stored or processed as a
unit.
fixed disk. A rigid magnetic disk used in a fixed disk
drive.
fixed disk drive. A disk storage device that reads and
writes on rigid magnetic disks.
full duplex. Synonym for duplex.
G
gateway. (1) A functional unit that connects two
computer networks of different network architectures.
generate. In 3174 central site customizing, to write a
Control diskette containing the customizing data for a
particular controller. Also, to print a mailing address
label and a diskette label for a particular controller.
H
host application program. An application program
processed in the host computer.
host attachment. A mode of SNA communication in
which the processor acts as a secondary SNA device.
host computer. (1) In a computer network, a computer
that provides end users with services such as
computation and data bases and that usually performs
network control functions. (2) The primary or
controlling computer in a multiple-computer
installation. (3) A computer used to prepare programs
for use on another computer or on another data
processing system; for example, a computer used to
compile link edit, or test programs to be used on
another system. (4) Synonym for host processor.
host logical unit (lU). An SNA logical unit (LU) located
in a host processor, for example, an ACF/VTAM
application program.
host processor. (1) A processor that controls all or
part of a user application network. (2) In a network,
the processing unit in which resides the access method
for the network. (3) In an SNA network, the processing
unit that contains a system services control point
(SSCP). (4) A processing unit that executes the access
method for attached communication controllers.
(5) The processing unit required to create and maintain
PSS. (6) Synonymous with host computer.
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 work stations connected to it.
IBM Cabling System. A permanently installed wiring
system that eliminates the need to rewire when
terminals are moved from one location to another
within an office complex. It allows transmission of data
at very high speeds and is the foundation for installing
a local area network.
immediate access storage. A storage device whose
access time is negligible in comparison with other
operating times.
initial microcode load (IMl). The action of loading the
operational microcode.
inputloutput
(I/O).
(1) Pertaining to a device whose
parts can perform an input process and an output
process at the same time. (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. (3) Pertaining to
input, output, or both.
interface. (1) A shared boundary between two
functional units, defined by functional characteristics,
common physical interconnection characteristics,
signal characteristics, and other characteristics as
appropriate. (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. (3) Hardware, software, or both,
that links systems, programs, or devices.
L
leased line. Synonym for nons witched line.
link. The logical connection between nodes including
the end-to-end link control procedures.
local. Pertaining to a device accessed directly without
use of a telecommunication line. Synonym for
channel-attached. Contrast with remote.
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IBM 3270 Information Display System 3174 Establishment Controller Introduction