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between communicating parties. (2) In SNA, the
meanings of and the liequencing rules for the following:
requests and responses used for managing the network,
transferring data, and synchronizing the states of
network components.
protocol conversion. For the 3708, the changing of \
start-stop data sent from an ASCII device to an SNA\
host (NCP) into 3270 data, or the changing of 3270 data
sent from an SNA host (NCP) to an ASCII device into \
ASCII start-stop data.
protocol conversion mode. For an ASCII device
attached to a 3708, a mode of operation in which the
device communicates with an SNA host (NCP) as
though it were a 3270 device.
protocol enveloping. For the 3708, the adding of SNA
headers to data sent from an ASCII device to an SNA
host (NCP), or the removing of SNA headers from data
sent from an SNA host (NCP) to an ASCII device.
protocol enveloping mode. For an ASCII device
attached to a 3708, a mode of operation in which the
device communicates with an SNA host (NCP) as
though it were an NTO device.
RAM. Random access memory.
routing. (1) The assignment of the path by which a
message reaches its destination. (2) In SNA, the
forwarding of a message unit along a particular path
through a network, as determined by parameters carried
in the message unit, such as the destination network
address in a transmission header.
secondary logical unit (SLU). In SNA, the logical unit
(LU) that contains the secondary half-session for a
particular LU-LU session. Contrast with primary
logical unit.
switched line. A telecommunication line in which the
connection is established by dialing. Contrast with
nonswitched line.
SNA character string (SCS). A character string
composed of EBCDIC controls, optionally intermixed
with end-user data, that is carried within a
request/response unit.
Synchronous Data Link Control (SDLC). A discipline
for managing synchronous, code-transparent,
serial-by-bit information transfer over a link connection.
Transmission exchanges may be duplex or half duplex
over switched or nonswitched links. The configuration
of the link connection may be point-to-point,
multipoint, or loop. SDLC conforms to subsets of the
Advanced Data Communication Control Procedures of
the American Standards Institute and High-Level Data
Link Control (HDLC) of the International Standards
Organization.
Systems Network Architecture (SNA). The description
of the logical structure, formats, protocols, and
operational sequences for transmitting information units
through and controlling the configuration and operation
of networks.
translate table. For the 3708, a table that defines the
translation of ASCII to EBCDIC and EBCDIC to
ASCII and that allows the use of special characters and
nonstandard codes.
user-defined terminal. An ASCII display that is
attached to the 3708 and that operates in protocol
conversion mode using a keyboard map defined by the
user.
user-defined terminal table. A table, which contains
information for a keyboard map used to define a
terminal, that a customer creates in storage.
wraparound. (1) (TC97) In computer graphics, the
display at some point on the display space of the display
elements whose coordinates lie outside of the display
space. (2) (TC97) In display-based word processing
equipment, the automatic disposition of a printable line
of text onto two or more display lines necessitated by
the horizontal limits of the display. (3) The
continuation of an operation from the maximum
addressable location in storage to the first addressable
location. (4) The continuation of register addresses
from the highest register address to the lowest.
3270 data stream. Data being transferred from or to an
allocated primary or tertiary device, or to the host
(NCP) system, as a continuous stream of data and 3270
Information Display System control elements in
character form.
3270 data-stream compatibility (DSC). The facility that
provides access to System/370 applications that
communicate with 3270 Information Display System
terminals.
3708 Network Conversion Unit. A device that allows
ASCII devices to communicate with an SNA host
(NCP) by providing protocol conversion and protocol
enveloping and that allows ASCII devices to
communicate with an ASCII host (NCP) by providing
ASCII pass-through.
Glossary
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