IBM 3745 Series Service Functions page 301

stored and executed in the unit. Examples are the
IBM 3705, IBM 3725/3726, IBM 3720, and IBM 3745.
communication network management (CNM) applica-
tion program. An ACF/VTAM application program
authorized to issue formatted management services
request units containing physical-unit-related requests
and to receive formatted management services
request units containing information from physical
units.
communication scanner. See scanner.
communication scanner processor (CSP). The
processor of a scanner.
communication subsystem. The part of the controller
that controls the data transfers over the transmission
interface.
configuration data file (CDF). A MOSS file that con-
tains a description of all the hardware features (pres-
ence, type, address, and characteristics).
control panel. A panel that contains switches and
indicators for the use of the customer's operator and
service personnel.
control program. A computer program designed to
schedule and to supervise the execution of programs
of the controller.
control subsystem (CSS). The
part
of the controller
that stores and executes the control program, and
monitors the data transfers over the channel and
transmission interfaces.
customer engineer (CE). See IBM service represen-
tative
cyclic redundancy check. A system of error checking
performed at both the sending and receiving station
after a block check character has been accumulated.
cyclic redundancy check character (CRC). A char-
acter used in a modified cyclic code for error
detection and correction.
data circuit-terminating equipment (DC E). The equip-
ment installed at the user's premises that provides all
the functions required to establish, maintain, and ter-
minate a connection, and the signal conversion and
coding between the data terminal equipment (DTE)
and the line. For example, a modem is a DCE (see
modem.)
Note: The DCE may be separate equipment or an
integral part of other equipment.
data communication channel.
See channel.
data host. A host running application programs only.
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3745 Communication Controller
data terminal equipment (DTE). That part of a data
station that serves as a data source, data link, or
both, and provides for the data communication control
function according to protocols.
DIN. Technology of connector contacts.
direct attachment. The attachment of a DTE to
another DTE without a DCE.
direct-current interlock (DCI). A mode of data
transfer over an I/O interface to enable communi-
cation between data processing systems through a
channel.
diskette. A thin, flexible magnetic disk, and its pro-
tective jacket, that records diagnostics, microcode,
and 3745 files.
diskette drive. A mechanism that reads and writes
diskettes.
DOSNS. Disk Operating System/Virtual Storage.
duplex transmission. Data transmission in both
directions at the same time. Contrast with
half-duplex.
Emulation Program (EP). An IBM licensed program
that allows a channel-attached communication con-
troller to emulate the functions of an IBM 2701 Data
Adapter Unit, an IBM 2702 Transmission Control, or
an IBM 2703 Transmission Control.
error recovery procedure (ERP). A procedure
designed to help isolate and, where possible, to
recover from errors in equipment. The procedures
are often used in conjunction with programs that
record the information on machine malfunctions.
fallback. In twin-backup mode, a state where the
traffic of the failing CCU has been redirected to the
second one.
In standby mode, a state where the traffic of the
failing CCU has been redirected to the standby CCU
after it is IPLed.
front-end scanner (FES). A circuit that scans the
transmission lines, serializes and deserializes the
transmitted characters, and manages the line ser-
vices. It is part of the scanner.
half-duplex. Data transmission in either direction,
one direction at a time. Contrast with duplex.
high-performance transmission subsystem (HPTSS).
The part of the controller that controls the data trans-
fers over the high-speed transmission interface
(speed up to 2 million bps).
The HPTSS consists of up to eight high-speed scan-
ners (HSSs).