IBM 990 - Manual (Page 265)

© Copyright IBM Corp. 2003, 2004 253
Glossary
active configuration. In an ESCON environment, the
ESCON Director configuration determined by the
status of the current set of connectivity attributes.
Contrast with saved configuration.
allowed. In an ESCON Director, the attribute that,
when set, establishes dynamic connectivity capability.
Contrast with prohibited.
American National Standards Institute (ANSI) . An
organization consisting of producers, consumers, and
general interest groups, which establishes the
procedures by which accredited organizations create
and maintain voluntary industry standards in the
United States.
ANSI. See American National Standards Institute.
APAR. See authorized program analysis report.
authorized program analysis report (APAR). A
report of a problem caused by a suspected defect in a
current, unaltered release of a program.
basic mode. A S/390 central processing mode that
does not use logical partitioning. Contrast with logically
partitioned (LPAR) mode.
blocked. In an ESCON Director, the attribute that,
when set, removes the communication capability of a
specific port. Contrast with unblocked.
CBY. Mnemonic for an ESCON channel attached to an
IBM 9034 convertor. The 9034 converts from ESCON
CBY signals to parallel channel interface (OEMI)
communication operating in byte multiplex mode (Bus
and Tag). Contrast with CVC.
chained. In an ESCON environment, pertaining to the
physical attachment of two ESCON Directors (ESCDs)
to each other.
channel path (CHP). A single interface between a
central processor and one or more control units along
which signals and data can be sent to perform I/O
requests.
channel path identifier (CHPID). In a Channel
Subsystem, a value assigned to each installed channel
path of the system that uniquely identifies that path to
the system.
Channel Subsystem (CSS). Relieves the processor of
direct I/O communication tasks, and performs path
management functions. Uses a collection of
subchannels to direct a channel to control the flow of
information between I/O devices and main storage.
channel. (1) A processor system element that controls
one channel path, whose mode of operation depends
on the type of hardware to which it is attached. In a
Channel Subsystem, each channel controls an I/O
interface between the channel control element and the
logically attached control units. (2) In the ESA/390
architecture, the part of a Channel Subsystem that
manages a single I/O interface between a Channel
Subsystem and a set of controllers (control units).
channel-attached. (1) Pertaining to attachment of
devices directly by data channels (I/O channels) to a
computer. (2) Pertaining to devices attached to a
controlling unit by cables rather than by
telecommunication lines.
CHPID. Channel path identifier.
cladding. In an optical cable, the region of low
refractive index surrounding the core. See also core
and optical fiber.
CNC. Mnemonic for an ESCON channel used to
communicate to an ESCON-capable device.
configuration matrix. In an ESCON environment, an
array of connectivity attributes that appear as rows and
columns on a display device and can be used to
determine or change active and saved configurations.
connected. In an ESCON Director, the attribute that,
when set, establishes a dedicated connection between
two ESCON ports. Contrast with disconnected.
connection. In an ESCON Director, an association
established between two ports that provides a physical
communication path between them.
connectivity attribute. In an ESCON Director, the
characteristic that determines a particular element of a
port's status. See allowed, blocked, connected,
disconnected, prohibited,
and unblocked.
control unit. A hardware unit that controls the reading,
writing, or displaying of data at one or more
input/output units.