IBM 3745 Service Functions page 290

o
o
o
D
synchronous transmission. Data transmission in
which the sending and receiving instruments are
operating continuously at substantially the same fre-
quency and are maintained, by means of correction,
in a desired phase relationship. Contrast with
asyn-
chronous transmission.
Systems Network Architecture (SNA). The
description of the logical structure, formats, protocols,
and operational sequences for transmitting informa-
tion through a user application network. The struc-
ture of SNA allows the users to be independent of
specific telecommunication facilities.
time out. The time interval allotted for certain oper-
ations to occur.
token-ring subsystem (TRSS). The part of the con-
troller that controls the data transfers over an IBM
Token-Ring Network.
The TRSS consists of up to four token-ring adapters
(TRAs).
token-ring adapter (TRA). Line adapter for an IBM
Token-Ring Network, composed of one token-ring
multiplexer card (TRM), and two token-ring interface
couplers (TICs).
The TRSS consists of up to four token-ring adapters
(TRAs).
transmission interface. The interface between the
controller and ,the user application network.
transmission line. The physical means for connecting
two or more DTEs (via DCEs). It can be nonswitched
or switched. Also called
line.
transmission subsystem (TSS). The part of the con-
troller that controls the data transfers over low- and
medium-speed, switched and non switched trans-
mission interfaces.
The TSS consists of:
• Up to 8 low-speed scanners (LSSs) associated
with
• lIC units (lIUs), through
• Serial links (SLs).
TSST board. Line adapter board for token-ring
adapters.
two-processor switch (TPS). A feature of the channel
adapter that connects a second channel to the same
adapter.
user application network. A configuration of data
processing products, such as processors, con,tro/lers,
and terminals, for the purpose of data processing and
information exchange. This configuration may use
circuit-switched, packet-switched, and leased-circuit
services provided by carriers or the PTT. Also called
user network.
vertical redundancy check (VRC). An odd parity
check performed on each character of a block as the
block is received.
V.24,25,35. EIA/CCITT recommendations on trans-
mission interfaces.
X.20 bis, 21,21 bis, 21 native, 25. CCITT recommen-
dations on transmission interfaces.
Glossary
X-1S