IBM 3174 Reference Manual page 209

switched line. See also manual answering. Contrast
with automatic calling.
automatic calling. (1) Calling In which the elements of
the selection signal are entered Into the data network
contiguously at the full data signaling rate. (2) A
machine feature that permits a station to Initiate a
connection with another station over a switched line
without operator action. (3) Synonymous with
auto-call. See also manual calling. Contrast with
automatic answering.
B
background logical terminal (LT). In MLT, any logical
terminal that Is not currently displayed. Contrast with
active logical terminal (LT).
blink. An extended highlighting attribute value (for
emphasis) of a field or character.
buffer. (1) A routine or storage used to compensate
for a difference In rate of flow of data, or time of
occurrence of events, when transferring data from one
device to another. (2) An Isolating circuit used to
prevent a driven circuit from Influencing the driving
circuit. (3) To allocate and schedule the use of buffers.
(4) A portion of storage used to hold Input or output
temporarily.
cliange-screen key. In MLT, a key or sequence of keys
on a display station keyboard used to change sessions,
one at a time, with up to five different hosts.
cliaracter mode. A mode In which Input Is treated as
alphanumeric data, rather than graphic data.
character position. A location on the screen at which
one character can be displayed; also, an addressed
location In the buffer at which 1 character can be
stored.
character set. (1) A defined collection of characters.
(2) A group of characters used for a specific reason,
for example, the set of characters a printer can print.
(3) The collection of graphic characters required to
support a specific language.
command. An Instruction that directs a control unit or
device to perform an operation or a set of operations.
configuration. The arrangement of a computer system
or network as defined by the nature, number, and chief
characteristics of Its functional units. More specifically,
the term configuration may refer to a hardware
configuration or a software configuration. See also
system configuration.
Connection Menu. A menu on the screen of a display
station attached to the 3174 Establishment Controller,
from which a user can select an available host.
controller. A unit that controls Input/output operations
for one or more devices.
control unit terminal (CUT). A terminal that relies on
the 3174 to Interpret the data stream. Examples are the
3178, 3179, 3278 Model 2, and 3279 Model S2A.
control unit terminal (CUT) mode. A host-Interactive
mode that enables an IBM 3270 Personal Computer
customized In this mode to run only one session
emulating a 3178, 3179, 3278 Model 2, or 3279 Model
S2A.
copy operation. An operation that copies the contents
of the buffer from one terminal to another terminal
attached to the same control unit.
country extended code page (CECP). A function of the
3174 microcode that provides for a code page
containing additional code points beyond those
available with Table 5A code pages. CECP Is
supported by a universal character set. Character Set
697, which contains 190 characters.
cursor. (1) A movable, visible mark used to Indicate
the position at which the next operation will occur on a
display surface. (2) A unique symbol that Identifies a
character position in a screen display, usually the
character position at which the next character to be
entered from the keyboard will be displayed.
customization. Procedures that tailor the control unit
microcode to fit the various types of display stations
and printers and the method of host attachment that a
particular control unit will handle.
Data Entry keyboard. A keyboard layout designed for
data entry applications.
data stream. (1) All data transmitted through a data
channel In a single read or write operation. (2) A
continuous stream of data elements being transmitted,
or Intended for transmission. In character or
binary-dlgit form, using a defined format. See also data
stream format.
data terminal equipment (DIE). That part of a data
station that serves as a data source, data sink, or both.
Data Terminal Ready (DTR) flow control. A procedure
for a communicating device to signal Its readiness to
receive data by raising the DTR lead on an EIA 2320
Interface.
X-4 3174 Establishment Controller Terminal User's Reference for Expanded Functions