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.

ADMF. Asynchronous Data Mover Facility.

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.

AP. Adjunct processor.

APAR. See authorized program analysis report.

Application Assist Processor (AAP). A special processor configured for running Java applications on z9 EC, z990 and z890 class machines.

ARP. Address Resolution Protocol.

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.

BBU. Battery Back-up Unit.

BL. Parallel block multiplexer channel.

blocked. In an ESCON Director, the attribute that, when set, removes the communication capability of a specific port. Contrast with unblocked.

BPA. Bulk Power Assembly.

bus. (1) A facility for transferring data between several devices located between two end points, only one device being able to transmit at a given moment. (2) A network configuration in which nodes are interconnected through a bidirectional transmission medium. (3) One or more conductors used for transmitting signals or power.

BY. Parallel byte multiplexer channel.

CAP. Cryptographic Asynchronous Processor.

CAW. channel address word.

CBA. Concurrent Book Add

CBP. Integrated cluster bus Coupling Facility peer channel.

CBU. Capacity BackUp.

CBY. ESCON byte multiplexer channel.

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.

CCC. Channel control check.

CCF. Cryptographic Coproprocessor Facility.

CCL. Communication Controller for Linux CCL.

CCW. Channel command word.

CDC. Channel data check.

CEC. Central Electronic Complex.

central processor complex. A physical collection of hardware that consists of Central Storage, one or more central processors, timers, and channels.

central processor. The part of the computer that contains the sequencing and processing facilities for instruction execution, initial program load, and other machine operations.

CFCC. Coupling Facility Control Code.

chained. In an ESCON environment, pertaining to the physical attachment of two ESCON Directors (ESCDs) to each other.

channel address. In S/370™ mode, the 8 left-most bits of an input/output address that identify the channel. See also device address and input/output address.

channel control check. A category of I/O errors affecting channel controls and sensed by the channel to which a device is attached. See also channel data check.

channel data check. A category of I/O errors, indicating a machine error in transferring data to or from storage and sensed by the channel to which a device is attached. See also channel control check.

channel Licensed Internal Code. That part of the Channel Subsystem Licensed Internal Code used to start, maintain, and end all operations on the I/O interface. See also IOP Licensed Internal Code.

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 configuration. In an ESCON or FICON environment, the connection between a channel and a control unit or between a channel, an ESCON Director, and one or more control units. See also point-to-point channel path configuration, and switched point-to-point channel path configuration.

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 and z/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.

channel-to-channel adapter (CTCA). An input/output device that is used by a program in one system to communicate with a program in another system.

check stop. The state that occurs when an error makes it impossible or undesirable to continue the operation in progress.

CHPID. Channel path identifier.

CIU. Customer Initiated Upgrade.

cladding. In an optical cable, the region of low refractive index surrounding the core. See also core and optical fiber.

CMOS. Complementary metal-oxide semiconductor.

CMT. CHPID Mapping Tool.

CNC. Mnemonic for an ESCON channel used to communicate to an ESCON-capable device.

command chaining. The fetching of a new channel command word (CCW) immediately following the completion of the previous CCW.

command retry. A channel and control unit procedure that causes a command to be retried without requiring an I/O interrupt.

concurrent maintenance. Hardware maintenance actions performed by a service representative while normal operations continue without interruption. See also nondisruptive installation and nondisruptive removal.

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.

core. (1) In an optical cable, the central region of an optical fiber through which light is transmitted. (2) In an optical cable, the central region of an optical fiber that has an index of refraction greater than the surrounding cladding material. See also cladding and optical fiber.

coupler. In an ESCON environment, link hardware used to join optical fiber connectors of the same type. Contrast with adapter.

Coupling Facility control code. The Licensed Internal Code (LIC) that runs in a Coupling Facility logical partition to provide shared storage management functions for a sysplex.

Coupling Facility. A special logical partition that provides high-speed caching, list processing, and locking functions in a sysplex.

CP. Central Processor.

CPACF. CP Assist for Cryptographic Function.

CPC. Central Processor Complex.

CPU. Central Processing Unit.

CTC. (1) Channel-to-channel. (2) Mnemonic for an ESCON channel attached to another ESCON channel.

CTCA. See channel-to-channel adapter.

CU. Control unit.

CUA. Control unit address.

CUADD. Control unit logical address.

CUoD. Capacity Upgrade on Demand

CVC. Mnemonic for an ESCON channel attached to an IBM 9034 convertor. The 9034 converts from ESCON CVC signals to parallel channel interface (OEMI) communication operating in block multiplex mode (Bus and Tag). Contrast with CBY.

DAT. Dynamic address translation.

data sharing. The ability of concurrent subsystems (such as DB2 or IMS DB) or application programs to directly access and change the same data while maintaining data integrity.

data streaming. In an I/O interface, a mode of operation that provides a method of data transfer at up to 4.5 MB per second. Data streaming is not interlocked between the sender and the receiver. Once data transfer begins, the sender does not wait for acknowledgment from the receiver before sending the next byte. The control unit determines the data transfer rate.

DCA. Distributed Converter Assembly.

DCAF. Distributed Console Access Facility.

DCM. Dynamic CHPID Management.

DDM. See disk drive module.

dedicated connection. In an ESCON Director, a connection between two ports that is not affected by information contained in the transmission frames. This connection, which restricts those ports from communicating with any other port, can be established or removed only as a result of actions performed by a host control program or at the ESCD console. Contrast with dynamic connection. Note: The two links having a dedicated connection appear as one continuous link.

default. Pertaining to an attribute, value, or option that is assumed when none is explicitly specified.

DES. Data Encryption Standard.

destination. Any point or location, such as a node, station, or a particular terminal, to which information is to be sent.

device address. In the ESA/390 architecture and the z/Architecture, the field of an ESCON or FICON (FC mode) device-level frame that selects a specific device on a control-unit image.

device number. (1) In the ESA/390 architecture and the z/Architecture, a four-hexidecimal-character identifier, for example 19A0, that you associate with a device to facilitate communication between the program and the host operator. (2) The device number that you associate with a subchannel that uniquely identifies an I/O device.

device. A mechanical, electrical, or electronic contrivance with a specific purpose.

DH. Diffie Hellman.

direct access storage device (DASD). A mass storage medium on which a computer stores data.

disconnected. In an ESCON Director, the attribute that, when set, removes a dedicated connection. Contrast with connected.

disk drive module (DDM). A disk storage medium that you use for any host data that is stored within a disk subsystem.

disk. A physical or logical storage media on which a computer stores data (is also sometimes referred to as a magnetic disk).

distribution panel. (1) In an ESCON or FICON environment, a panel that provides a central location for the attachment of trunk and jumper cables and can be mounted in a rack, wiring closet, or on a wall.

duplex connector. In an ESCON environment, an optical fiber component that terminates both jumper cable fibers in one housing and provides physical keying for attachment to a duplex receptacle.

duplex receptacle. In an ESCON environment, a fixed or stationary optical fiber component that provides a keyed attachment method for a duplex connector.

duplex. Pertaining to communication in which data or control information can be sent and received at the same time. Contrast with half duplex.

dynamic connection. In an ESCON Director, a connection between two ports, established or removed by the ESCD and that, when active, appears as one continuous link. The duration of the connection depends on the protocol defined for the frames transmitted through the ports and on the state of the ports. Contrast with dedicated connection.

dynamic connectivity. In an ESCON Director, the capability that allows connections to be established and removed at any time.

dynamic I/O Reconfiguration. A S/390 function that allows I/O configuration changes to be made nondisruptively to the current operating I/O configuration.

dynamic storage reconfiguration. A PR/SM LPAR function that allows central or Expanded Storage to be added or removed from a logical partition without disrupting the system control program operating in the logical partition.

EBA. Enhanced Book Availability.

ECC. Error checking and correction.

ECKD. Extended count key data.

EEPROM. electrically erasable programmable read only memory.

EIA. Electronics Industries Association. One EIA unit is 1.75 inches or 44.45 mm.

EMIF. See ESCON Multiple Image Facility.

Enterprise System Connection (ESCON). (1) An ESA/390 computer peripheral interface. The I/O interface uses ESA/390 logical protocols over a serial interface that configures attached units to a communication fabric. (2) A set of IBM products and services that provide a dynamically connected environment within an enterprise.

Enterprise Systems Architecture/390® (ESA/390). An IBM architecture for mainframe computers and peripherals. Processors that follow this architecture include the S/390 Server family of processors.

environmental error record editing and printing program (EREP). The program that makes the data contained in the system recorder file available for further analysis.

EPO. Emergency power off.

ESA/390. See Enterprise Systems Architecture/390.

ESCD console. The ESCON Director display and keyboard device used to perform operator and service tasks at the ESCD.

ESCD. Enterprise Systems Connection (ESCON) Director.

ESCM. Enterprise Systems Connection Manager.

ESCON channel. A channel having an Enterprise Systems Connection channel-to-control-unit I/O interface that uses optical cables as a transmission medium. May operate in CBY, CNC, CTC, or CVC mode. Contrast with parallel channel.

ESCON Director. An I/O interface switch that provides the interconnection capability of multiple ESCON interfaces (or FICON FCV (9032-5) in a distributed-star topology.

ESCON Multiple Image Facility (MIF). A function that allows logical partitions to share an ESCON channel path (and other channel types) by providing each logical partition with its own channel-subsystem image.

ESCON. See Enterprise System Connection.

ETR. External time reference.

FC-AL. Fibre Channel Arbitrated Loop.

FCS. See Fibre Channel standard.

FCTC. FICON Channel-to-Channel.

fiber optic cable. See optical cable.

fiber optics. The branch of optical technology concerned with the transmission of radiant power through fibers made of transparent materials, such as glass, fused silica, and plastic.

Note: Telecommunication applications of fiber optics use optical fibers. Either a single discrete fiber or a non-spatially aligned fiber bundle can be used for each information channel. Such fibers are often called optical fibers to differentiate them from fibers used in non-communication applications.

fiber. See optical fiber.

Fibre Channel standard. An ANSI standard for a computer peripheral interface. The I/O interface defines a protocol for communication over a serial interface that configures attached units to a communication fabric. The protocol has four layers. The lower of the four layers defines the physical media and interface, the upper of the four layers defines one or more logical protocols (for example, FCP for SCSI command protocols and FC-SB-2 for FICON for ESA/390). Refer to ANSI X3.230.1999x.

FICON channel. A channel having a Fibre Channel channel-to-control-unit I/O interface that uses optical cables as a transmission medium. The FICON channel may operate in (1) FC mode (FICON native mode - FC-SB-2/3), (2) FCV mode (FICON conversion mode to a IBM 9032-5), or (3) FCP mode (FICON channel operating in "open mode", which is FC-FCP).

FICON. (1) An ESA/390 and z/Architecture computer peripheral interface. The I/O interface uses ESA/390 and z/Architecture logical protocols over a FICON serial interface that configures attached units to a FICON communication fabric. (2) An FC4 adopted standard that defines an effective mechanism for the export of the SBCON command protocol via Fibre Channels.

field replaceable unit (FRU). An assembly that is replaced in its entirety when any one of its required components fails.

FRU. Field-replaceable unit.

GARP. Generic Attribute Registration Protocol.

Gb. Gigabit.

GB. Gigabyte.

GbE. Gigabit Ethernet.

gigabit (Gb). A unit of measure for storage size. One gigabit equals one billion bits.

Gigabit (Gb). Usually used to refer to a data rate, the number of gigabits being transferred in one second.

Gigabit Ethernet. An OSA channel (type OSD).

gigabyte (GB). (1) A unit of measure for storage size. One gigabyte equals 1,073,741,824 bytes. (2) Loosely, one billion bytes.

GVRP. GARP VLAN Registration Protocol.

half duplex. In data communication, pertaining to transmission in only one direction at a time. Contrast with duplex.

hard disk drive. (1) A storage media within a storage server used to maintain information that the storage server requires. (2) A mass storage medium for computers that is typically available as a fixed disk or a removable cartridge.

Hardware Management Console. A console used to monitor and control hardware such as the z9 EC or zSeries processors.

hardware system area (HSA). A logical area of Central Storage, not addressable by application programs, used to store Licensed Internal Code and control information.

HCD. Hardware configuration definition.

HDA. Head and disk assembly.

HDD. See hard disk drive.

head and disk assembly. The portion of an HDD associated with the medium and the read/write head.

I/O configuration. The collection of channel paths, control units, and I/O devices that attaches to the processor. This may also include channel switches (for example, an ESCON Director).

I/O. See input/output.

IBB. Internal Bus Buffer

IBF. Internal Battery Feature.

ICB. Integrated Cluster Bus link.

ICF. Internal Coupling Facility.

ICP. Internal Coupling Facility peer channel.

ICSF. Integrated Cryptographic Service Facility.

ID. See identifier.

IDAW. Indirect data address word.

Identifier. A unique name or address that identifies things such as programs, devices, or systems.

IFCC. Interface control check.

IFL. Integrated Facility for Linux.

IML. Initial machine load. A procedure that prepares

a device for use.

IMS. Information Management System.

initial machine load (IML). A procedure that prepares a device for use.

initial program load (IPL). (1) The initialization procedure that causes an operating system to commence operation. (2) The process by which a configuration image is loaded into storage at the beginning of a work day or after a system malfunction. (3) The process of loading system programs and preparing a system to run jobs.

input/output (I/O). (1) Pertaining to a device whose parts can perform an input process and an output process at the same time. (2) Pertaining to a functional unit or channel involved in an input process, output process, or both, concurrently or not, and to the data involved in such a process. (3) Pertaining to input, output, or both.

input/output configuration data set (IOCDS). The data set in the S/390 processor (in the support element) that contains an I/O configuration definition built by the input/output configuration program (IOCP).

input/output configuration program (IOCP). A S/390 program that defines the channels, I/O devices, paths to the I/O devices, and the addresses of the I/O devices to a system. The output is normally written to a S/390 IOCDS.

Integrated Facility for Applications (IFA). A general purpose assist processor for running specific types of applications. See Application Assist Processor (AAP).

interface. (1) A shared boundary between two functional units, defined by functional characteristics, signal characteristics, or other characteristics as appropriate. The concept includes the specification of the connection of two devices having different functions. (2) Hardware, software, or both, that links systems, programs, or devices.

IOCDS. See Input/Output configuration data set.

IOCP. See Input/Output configuration control program.

IODF. The data set that contains the S/390 I/O configuration definition file produced during the defining of the S/390 I/O configuration by HCD. Used as a source for IPL, IOCP, and Dynamic I/O Reconfiguration.

IPL. See initial program load.

IRD. Intelligent Resource Director.

ISC-3. Inter System Channel-3.

ISDN. Integrated-Services Digital Network.

ITR. Internal throughput rate.

ITRR. Internal Throughput rate ratio.

jumper cable. In an ESCON and FICON environment, an optical cable having two conductors that provides physical attachment between a channel and a distribution panel or an ESCON Director port or a control unit/devices, or between an ESCON Director port and a distribution panel or a control unit/device, or between a control unit/device and a distribution panel. Contrast with trunk cable.

LAN. See local area network.

laser. A device that produces optical radiation using a population inversion to provide light amplification by stimulated emission of radiation and (generally) an optical resonant cavity to provide positive feedback. Laser radiation can be highly coherent temporally, or spatially, or both.

LC connector. An optical fibre cable duplex connector that terminates both jumper cable fibres into one housing and provides physical keying for attachment to an LC duplex receptacle. For technical details, see the NCITS - American National Standard for Information Technology - Fibre Channel Standards document FC-PI.

LCSS. See Logical Channel Subsystem.

LCU. See Logical Control Unit.

LED. See light emitting diode.

LIC. See Licensed Internal Code.

LIC-CC. Licensed Internal Code Configuration Control.

Licensed Internal Code (LIC). Software provided for use on specific IBM machines and licensed to customers under the terms of IBM's Customer Agreement. Microcode can be Licensed Internal Code and licensed as such.

light-emitting diode (LED). A semiconductor chip that gives off visible or infrared light when activated. Contrast Laser.

link address. On an ESCON or a FICON interface, the portion of a source or destination address in a frame that ESCON or FICON uses to route a frame through an ESCON or FICON director. ESCON and FICON associates the link address with a specific switch port that is on the ESCON or FICON director. Note: For ESCON, there is a one-byte link address. For FICON, there can be a one-byte or two-byte link address specified. One-byte link address for a FICON non-cascade topology and two-byte link address supports a FICON cascade switch topology. See also port address.

link. (1) In an ESCON or FICON environment, the physical connection and transmission medium used between an optical transmitter and an optical receiver. A link consists of two conductors, one used for sending and the other for receiving, thereby providing a duplex communication path. (2) In an ESCON or FICON I/O interface, the physical connection and transmission medium used between a channel and a control unit, a channel and an ESCON or FICON Director, a control unit and an ESCON or FICON Director, or, at times, between two ESCON Directors or two FICON Directors.

local area network (LAN). A computer network located in a user's premises within a limited geographic area.

logical address. The address found in the instruction address portion of the program status word (PSW). If translation is off, the logical address is the real address. If translation is on, the logical address is the virtual address.

Logical Channel Subsystem (LCSS). A defined subset of the server hardware (subchannels, channels, and I/O interfaces) that is used to support the operation of a Logical Channel Subsystem. The LCSS relieves the processor of direct I/O communication tasks, and performs path management functions. Uses a collection of subchannels (defined to the LCSS) to direct a channel to control the flow of information between its defined I/O devices and main storage.

logical control unit (LCU). A separately addressable control unit function within a physical control unit. Usually a physical control unit that supports several LCUs. For ESCON, the maximum number of LCUs that can be in a control unit (and addressed from the same ESCON fiber link) is 16; they are addressed from x'0' to x'F'.

logical partition (LPAR). A set of functions that create a programming environment that is defined by the ESA/390 and z/Architecture. A logical partition is conceptually similar to a virtual machine environment, except that LPAR is a function of the processor and does not depend on an operating system to create the virtual machine environment.

logical processor. In LPAR mode, a central processor in a logical partition.

logical switch number (LSN). A two-digit number used by the I/O Configuration Program (IOCP) to identify a specific ESCON Director.

logically partitioned (LPAR) mode. A central processor mode, available on the Configuration frame when using the PR/SM facility, that allows an operator to allocate processor hardware resources among logical partitions. Contrast with basic mode.

LPAR. See logical partition.

LUPS. Local Uninterruptible Power Supply.

MAC. Message Authentication Code.

machine check. An error condition that is caused by an equipment malfunction.

maintenance change level (MCL). A change to correct a single licensed internal code design defect. Higher quality than a patch, and intended for broad distribution. Considered functionally equivalent to a software PTF.

MAU. Multistation access unit.

Mb. Megabit.

MB. Megabyte.

MBA. Memory bus adapter.

MCCU. Multisystem channel communication unit.

MCL. See maintenance change level.

MCM. Multi Chip Module.

MDA. Motor Drive Assembly.

megabit (Mb). A unit of measure for storage size. One megabit equals 1,000,000 bits.

megabyte (MB). (1) A unit of measure for storage size. One megabyte equals 1,048,576 bytes. (2) Loosely, one million bytes.

MIDAW. Modified Indirect Data Address Word.

MIF. Multiple Image Facility.

MRU. Modular Refrigeration Unit.

MSA. Motor Scroll Assembly.

MSC chip. Memory Storage Control chip.

MT-RJ. An optical fibre cable duplex connector that terminates both jumper cable fibres into one housing and provides physical keying for attachment to an MT-RJ duplex receptacle. For technical details, see the NCITS - American National Standard for Information Technology - Fibre Channel Standards document FC-PI.

multidrop topology. A network topology that allows multiple control units to share a common channel path, reducing the number of paths between channels and control units.

multi-mode optical fiber. A graded-index or step-index optical fiber that allows more than one bound mode to propagate. Contrast with single-mode optical fiber.

Multiple Image Facility (MIF). In the ESA/390 architecture and z/Architecture, a function that allows logical partitions to share a channel path by providing each logical partition with its own set of subchannels for accessing a common device.

National Committee for Information Technology Standards. NCITS develops national standards and its technical experts participate on behalf of the United States in the international standards activities of ISO/IEC JTC 1, information technology.

NCITS. See National Committee for Information Technology Standards.

ND. See node descriptor.

NED. See node-element descriptor.

node descriptor. In an ESCON and FICON environment, a node descriptor (ND) is a 32-byte field that describes a node, channel, ESCON Director port, FICON Director port, or a control unit.

node-element descriptor. In an ESCON and FICON environment, a node-element descriptor (NED) is a 32-byte field that describes a node element, such as a disk device.

NPIV. N_Port ID Virtualization.

OEMI. See original equipment manufacturers information.

open system. A system whose characteristics comply with standards made available throughout the industry and that therefore can be connected to other systems complying with the same standards.

optical cable assembly. An optical cable that is connector-terminated. Generally, an optical cable that has been terminated by a manufacturer and is ready for installation. See also jumper cable and optical cable.

optical cable. A fiber, multiple fibers, or a fiber bundle in a structure built to meet optical, mechanical, and environmental specifications. See also jumper cable, optical cable assembly, and trunk cable.

optical fiber connector. A hardware component that transfers optical power between two optical fibers or bundles and is designed to be repeatedly connected and disconnected.

optical fiber. Any filament made of dialectic materials that guides light, regardless of its ability to send signals. See also fiber optics and optical waveguide.

optical waveguide. (1) A structure capable of guiding optical power. (2) In optical communications, generally a fiber designed to transmit optical signals. See optical fiber.

original equipment manufacturers information (OEMI). A reference to an IBM guideline for a computer peripheral interface. More specifically, refers to IBM S/360™ and S/370 Channel to Control Unit Original Equipment Manufacture's Information. The interfaces use ESA/390 and z/Architecture logical protocols over an I/O interface that configures attached units in a multi-drop bus environment.

parallel channel. A channel having a System/360™ and System/370™ channel-to-control-unit I/O interface that uses bus and tag cables as a transmission medium. Contrast with ESCON channel.

path group. The ESA/390 and z/Architecture term for a set of channel paths that are defined to a controller as being associated with a single S/390 image. The channel paths are in a group state and are online to the host.

path. In a channel or communication network, any route between any two nodes. For ESCON or FICON, this would be the route between the channel and the control unit/device, or sometimes from the operating system control block for the device and the device itself.

path-group identifier. The ESA/390 and z/Architecture term for the identifier that uniquely identifies a given logical partition. The path-group identifier is used in communication between the system image and a device. The identifier associates the path-group with one or more channel paths, thereby defining these paths to the control unit as being associated with the same system image.

PCHID. Physical Channel Identifier.

PCI. Peripheral Component Interconnect.

PCICC. PCI Cryptographic Coprocessor.

PCI-X. Peripheral Component Interconnect eXtended.

physical channel identifier (PCHID). A value assigned to each physically installed and enabled channel in the server that uniquely identifies that channel. For the System z9, the assigned PCHID values are between 000 and 6FF.

PIN. Personal Identification Number.

PKA. Public-Key-Algorithm.

PKSC. Public-Key Secure Cable.

POR. Power-on Reset.

port address. In an ESCON Director or a FICON Director, an address used to specify port connectivity parameters and to assign link addresses for attached channels and control units. See also link address.

port card. In an ESCON or FICON environment, a field-replaceable hardware component that provides the optomechanical attachment method for jumper cables and performs specific device-dependent logic functions.

port name. In an ESCON Director or a FICON Director, a user-defined symbolic name of 24 characters or less that identifies a particular port.

port. (1) An access point for data entry or exit. (2) A receptacle on a device to which a cable for another device is attached. See also duplex receptacle.

Power-on Reset state. The condition after a machine power-on sequence and before an IPL of the control program.

Power-on Reset. A function that re-initializes all the hardware in the system and loads the internal code that enables the machine to load and run an operating system. This function is intended as a recovery function.

PR/SM. Processor Resource/Systems Manager.

processor complex. A system configuration that consists of all the machines required for operation, for example, a Processor Unit, a processor controller, a system display, a service support display, and a power and coolant distribution unit.

program status word (PSW). An area in storage used to indicate the sequence in which instructions are executed, and to hold and indicate the status of the computer system.

program temporary fix (PTF). A temporary solution or bypass of a problem diagnosed by IBM in a current unaltered release of a program.

prohibited. In an ESCON Director or FICON Director, the attribute that, when set, removes dynamic connectivity capability. Contrast with allowed.

protocol. (1) A set of semantic and syntactic rules that determines the behavior of functional units in achieving communication. (2) In SNA, the meanings of and the sequencing rules for requests and responses used for managing the network, transferring data, and synchronizing the states of network components. (3) A specification for the format and relative timing of information exchanged between communicating parties.

PSC. Power Sequence Controller.

PSCN. Power Service Control Network.

PSP. Preventive Service Planning.

PTF. See program temporary fix.

QDIO. Queued Direct Input/Output.

RAS. Reliability, Availability, Serviceability.

remote service facility (RSF). (1) A control program plus associated communication equipment that allows local personnel to connect to an IBM service center, and allows remote personnel to operate the remote system or send new internal code fixes to it, if properly authorized. (2) A system facility invoked by Licensed Internal Code that provides procedures for problem determination and error detection.

RETAIN. Remote Technical Assistance and Information Network.

RII. Redundant I/O Interconnect.

RMF. Resource Measurement Facility.

route. The path that an ESCON frame or FICON frame (Fibre Channel frame) takes from a channel through an ESCON Director or FICON Director to a control unit/device.

RSA. Rivest-Shamir-Adelman.

saved configuration. In an ESCON or FICON environment, a stored set of connectivity attributes whose values determine a configuration that can be used to replace all or part of the ESCON Director's or FICON Director's active configuration. Contrast with active configuration.

SC chip. Storage Controller chip.

SC Connector. An optical fibre cable duplex connector that terminates both jumper cable fibres into one housing and provides physical keying for attachment to an LC duplex receptacle. For technical details, see the NCITS - American National Standard for Information Technology - Fibre Channel Standards document FC-PI.

SCP. System control program.

SCSW. Subchannel status word.

SD chip. System Data cache chip.

SE. See Support Element.

SEC. System Engineering Change.

Self-Timed Interconnect (STI). An interconnect path cable that has one or more conductors that transit information serially between two interconnected units without requiring any clock signals to recover that data. The interface performs clock recovery independently on each serial data stream and uses information in the data stream to determine character boundaries and inter-conductor synchronization.

Small Computer System Interface (SCSI). (1) An ANSI standard for a logical interface to a computer peripherals and for a computer peripheral interface. The interface uses a SCSI logical protocol over an I/O interface that configures attached targets and initiators in a multi-drop bus topology. (2) A standard hardware interface that enables a variety of peripheral devices to communicate with one another.

SNMP. Simple network management protocol.

spanning channels. Spanning channels have the ability to be configured to multiple Channel SubSystems, and be transparently shared by any or all of the configured logical partitions without regard to the Logical Channel SubSystem to which the logical partition is configured.

STI. See Self-Timed Interconnect.

STI-MP. Self-Timed Interconnect Multiplexor.

storage director. In a logical entity consisting of one or more physical storage paths in the same storage cluster.

STP. Server Time Protocol. A time synchronization feature designed to enable multiple servers to maintain time synchronization with each other.

subchannel. A logical function of a Channel Subsystem associated with the management of a single device.

subchannel. The facility that provides all of the information necessary to start, control, and complete an I/O operation. subchannel number. A system-unique 16-bit value used to address a subchannel.

subsystem. (1) A secondary or subordinate system, or programming support, usually capable of operating independently of or asynchronously with a controlling system.

Support Element (SE). (1) An internal control element of a processor that assists in many of the processor operational functions. (2) A hardware unit that provides communications, monitoring, and diagnostic functions to a central processor complex (CPC).

SWCH. In ESCON Manager, the mnemonic used to represent an ESCON Director.

switch. In ESCON Manager, synonym for ESCON Director.

switched point-to-point channel path configuration. In an ESCON or FICON I/O interface, a configuration that consists of a link between a channel and an ESCON Director and one or more links from the ESCD, each of which attaches to a control unit. This configuration depends on the capabilities of the ESCD for establishing and removing connections between channels and control units. Contrast with point-to-point channel path configuration.

switched point-to-point topology. A network topology that uses switching facilities to provide multiple communication paths between channels and control units. See also multidrop topology.

Sysplex Timer. An IBM table-top unit that synchronizes the time-of-day (TOD) clocks in as many as 16 processors or processor sides.

Sysplex. A set of systems communicating and cooperating with each other through certain multisystem hardware components and software services to process customer workloads.

system reset. To reinitialize the execution of a program by repeating the load operation.

TDES. Triple Data Encryption Standard.

time-of-day (TOD) clock. A system hardware feature that is incremented once every microsecond, and provides a consistent measure of elapsed time suitable for indicating date and time. The TOD clock runs regardless of whether the processor is in a running, wait, or stopped state.

TKE. Trusted Key Entry.

TOD. See Time of day.

TPF. See Transaction processing facility.

Transaction Processing Facility. Transaction Processing Facility is a specialized high availability operating system designed to provide quick response times to very high volumes of messages from large networks of terminals and workstations.

trunk cable. In an ESCON environment, a cable consisting of multiple fiber pairs that do not directly attach to an active device. This cable usually exists between distribution panels and can be located within, or external to, a building. Contrast with jumper cable.

TSO. Time sharing option.

UCW. Unit control word.

unblocked. In an ESCON Director, the attribute that, when set, establishes communication capability for a specific port. Contrast with blocked.

unit address. The ESA/390 and z/Architecture term for the address associated with a device on a given controller. On ESCON or FICON interfaces, the unit address is the same as the device address. On OEMI interfaces, the unit address specifies a controller and device pair on the interface.

UPC. Universal Power Controller.

UPS. Uninterruptible Power Supply.

VLAN. Virtual Local Area Network.

VPD. Vital Product Data.

WLM. WorkLoad Manager.

z/Architecture. An IBM architecture for mainframe computers and peripherals. Processors that follow this architecture include the System z9 and zSeries servers.

zAAP. System z9 and zSeries Application Assist Processor. See Application Assist Processor (AAP).