IBM 3174 Introduction Manual page 76

logical terminal (LT). In MLT, one of five sessions
available to share one display station.
logical unit (LU). In SNA, a port through which an end
user accesses the SNA network in order to
communicate with another end user and through which
the end user accesses the functions provided by
system services control points (SSCPs). An LU can
support at least two sessions, one with an SSCP and
one with another LU, and may be capable of supporting
many sessions with other logical units.
M
main storage. Program-addressable storage from
which instructions and other data can be loaded
directly into registers for subsequent processing.
maintenance analysis procedure (MAP). A
maintenance document that gives an IBM service
representative a step-by-step procedure for tracing a
symptom to the cause of a failure.
mark. A symbol or symbols that indicate the beginning
or the end of a field, a word, an item of data or a set of
data such as a file, record, or block.
medium. A physical carrier of electrical energy.
memory. Program-addressable storage from which
instructions and other data can be loaded directly into
registers for subsequent execution or processing.
Synonymous with main storage.
microcode. (1) One or more microinstructions. (2) A
code, representing the instructions of an instruction
set, that is implemented in a part of storage that is not
program-addressable. (3) To design, write, and also to
test one or more microinstructions.
multiple logical terminal (MLT). In the 3174, a function
that provides a CUT-attached, fixed-function display
station with the ability to interact with as many as five
host sessions. Each session is processed as though it
were a separate display station.
N
NetView. A comprehensive network management
product that is the basis for central control of both
systems for network operations. It supersedes NCCF,
NPDA, NLDM, and NPM.
network. (1) An arrangement of nodes and connecting
branches. Connections are made between data
stations. (2) A configuration of data processing
devices and software connected for information
interchange.
nonswltched line. (1) A connection between systems
or devices that does not have to be made by dialing.
Contrast with switched line. (2) A telecommunication
line on which connections do not have to be
established by dialing. Synonymous with leased line.
o
online test. A diagnostic test or data collection
program that is run without interrupting the normal
operation of the 3174 and its associated terminals.
original equipment manufacturer (OEM). A
manufacturer of equipment that may be marketed by
another manufacturer.
p
port. (1) An access poi nt for data entry or exit. (2) A
connector on a device to which cables for other devices
such as display stations and printers are attached.
protocol. (1) A set of semantic and syntactic rules that
determine the behavior of functional units in achieving
communication. (2) In SNA, the meanings of and the
sequencing rules for requests and responses used for
managing the network, transferring data, and
synchronizing the states of network components.
R
random access memory (RAM). A storage device into
which data is entered and from which data is retrieved
in a nonsequential manner. See also direct access
storage.
remote. Pertaining to a system, program, or device
that is accessed through a telecommunication line.
request for price quotation (RPQ). An alteration or
addition to the functional capabilities that the controller
provides.
Response Time Monitor (RTM). A network
management tool that measures and records the
transaction times of inbound host attention (AID)
operations from display stations that communicate with
the host.
ring interface adapter. A device that assumes the
basic data transmission functions of node, such as
frame recognition, address decoding, error checking,
buffering of frames, fault detection, and, in Token-Ring
Networks, token generation.
ring network. A network configuration where a series
of attaching devices are connected by unidirectional
transmission links to form a closed path.
Glossary
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