HP 3000 Manuals HP 3000 Manuals
Definitions (A-D)
abort A procedure that terminates a program or session if
an irrecoverable error, mistake, or malfunction
occurs, or if the system manager requests
termination.
access The process of obtaining data from files or
acquiring the use of a device. Access implies an
input/output (I/O) operation and is used as a
synonym for I/O.
access codes Access codes are assigned by the system manager to
accounts and by the account manager to groups, and
users. Access codes specify which users have the
ability to read, write, append, lock, or execute a
given file.
access control An ACD is how the owner of a file defines who can
definitions (ACDs) do what with the file. ACDs take precedence over
other access controls namely the MPE file access
matrix and lockwords. The types of access are read
(R), write (W), append (A), lock (L), execute (X),
none (NONE), and read and copy the ACD permission
file (RACD).
access method The way in which data is moved between main storage
and input/output devices.
access port (AP) The MPE/iX system console interfaces the host
system through the access port (AP) located in the
channel I/O (CIO) section of the system card cage.
The AP provides a user support interface for
issuing hard and soft resets through software
commands from the console. It allows a remote
console to be enabled and to switch between console
and session modes.
access rights field A field containing the type of memory access. It
(ARF) is compared with the user's privilege level to
determine if the type of access the user is
requesting (READ, WRITE, EXECUTE, or GATEWAY) is
allowed for that page of memory.
account A collection of users and groups. Each account has
a unique name on the system. It is the method used
to organize a system's users and files and track
use of system resources such as central processor
time, online connect time, and file space.
Accounts are the principal billing entity for the
use of these resources. Every user must specify an
account to access the system.
account level The types of file access assigned by the system
security manager to the account when it is created. The
types of access are READ, LOCK, APPEND, WRITE, and
EXECUTE, abbreviated R, L, A, W, and X
respectively. They may be assigned to any user
(ANY), members of the account only (AC), or members
of the group only (GU). The types of file access
permitted are the first level of system security.
The account manager may further restrict groups and
users within an account by assigning them a limited
set of file access modes.
account librarian A capability assigned by the account manager to a
capability (AL user within the account. An account librarian can
capability) be allowed special file access to maintain
specified files within the account.
account manager A capability assigned to one user within each
capability (AM account who is then responsible for establishing
capability) users and groups.
account member A person who has been granted access to the system
through the use of a valid user name within an
account. Account members are created by the
account manager, who defines the user name and
assigns the user appropriate capabilities and
security restrictions.
account structure The account structure provides organization,
security, and billing for the system. It is used
to allocate system resources such as central
processor time, online connect time, and file
space. The account is the principal billing entity
for the use of system resources.
acknowledge To answer or reply to a polling, an address, or a
message.
acoustic modem A data communications device. An acoustic modem
has a cradle and form-fitting rubber cups to hold a
telephone handset. The opposite of direct-connect
modem.
ACTIVE state The status of either an input or output spoolfile
(defined differently for each). During input
spooling, an ACTIVE file is a spoolfile being
created, indicating that the input spooler is still
collecting data from the input device. An ACTIVE
output spoolfile is the only file being output to a
device. For example, when the standard output
device is the system printer the file being printed
is ACTIVE.
actual file The file name provided by the user. The system
designator then uses the file name in place of the formal file
designator to accomplish some task. The actual
file designator is the file name listed in the
directory. See formal file designator.
address 1) A number identifying an exact location in
memory. A process can send data to, or retrieve
data from, this address.
2) A set of values identifying a specific
peripheral (I/O) device to the computer. The exact
details on the formation of an address differ
between systems.
address bus The electrical conductors within a computer. They
carry addresses from the CPU to components under
CPU control. The 900 Series HP 3000 address bus is
32-bits wide.
advanced terminal An intelligent hardware interface between terminals
processor (ATP) and the HP 3000. The ATP handles character
processing and eliminates CPU interrupts. It
supports full-duplex asynchronous modems and direct
memory access of user data.
AdvanceNet See HP AdvanceNet.
algorithm A step-by-step procedure for solving a problem in a
finite amount of time.
ALLBASE/SQL A Hewlett-Packard database management system. It
provides both network and relational interfaces.
allocate 1) To locate and reserve disk space for a
particular file.
2) To use the ALLOCATE command to update table
entries and resolve pointers necessary for a
program to execute. However, the program is not
actually loaded into memory until run time.
alpha character A character in the range of A through Z (or a-z).
alphanumeric A character in the range of A through Z (or a-z),
character or 0 through 9.
alpha test The designation given when the reliability of a
computer system is tested by internal users. For
example, internal Hewlett-Packard users test and
verify a new product before external customer tests
are conducted.
alternate boot path The hardware path used when booting the system from
a boot tape. See boot path.
American National A nongovernmental agency that establishes
Standards Institute standards, including those for data processing.
(ANSI)
American Standard The standard method of representing character data
Code for Information (seven data bits plus one that is sometimes used
Interchange (ASCII,
USASCII)
for parity). This method was established by the
American National Standards Institute (ANSI) to
achieve compatibility between data devices when
they are interchanging information.
analog Data that varies continuously rather than in
discrete steps. When used in reference to
circuits, it means those circuits that produce an
output varying as an uninterrupted function of the
input. The opposite of digital.
append To join all or part of one existing file to the end
of another existing file.
application A set of computer instructions or programs that
accomplish tasks for the end user, rather than
control the computer (that is what the operating
system does). Examples of applications include
spreadsheets, word processing programs, graphics,
database management, and communications.
application layer Layer seven of the Open Systems Interconnection
(OSI) network model. Application layer tasks
include the user interface to remote services.
application program A set of computer instructions that guides the
computer through a specific set of tasks (usually
for the end user). Applications include
spreadsheets, word processing, graphics, database
management, and data communication programs.
architecture 1) The unique set of machine instructions,
registers, and components, as well as the way they
interact, that provides the basis of the operation
of the computer's CPU.
2) In networking, a structured modular network
design in which different data communications tasks
are assigned to different layers or levels. See
Open Systems Interconnection.
archive mode A DBCore mode of logging that enables both rollback
and rollforward recovery for HP SQL databases.
archiving Storing infrequently used or out-of-date files onto
tape and permanently removing them from the system
disks at the same time.
arithmetic logic The part of a system that performs arithmetic and
unit (ALU) logic operations as part of the central processing
unit (CPU). The CPU may contain one or more
arithmetic logic units.
array An ordered collection of letters, numbers, or words
defined by the user. The computer stores the data
in an array in continuous memory.
ASCII American Standard Code for Information Interchange
(ASCII) is the standard method of representing
character data (seven bits plus one that can be
used for parity). This method was established by
the American National Standards Institute (ANSI) to
achieve compatibility between data devices when
they are exchanging information.
assembly language A programming language in which each operation
performed by the central processing unit (CPU) is
written as a symbolic instruction. Assembly
language is a convenient means of representing
machine language (one instruction represents
exactly one operation). A program known as an
assembler translates instructions written in
assembly language into machine language.
associated device A device associated with a user by way of the
ASSOCIATE command. Thereafter, the associated user
has operator control of the designated device until
the user logs off or gives up control of the
device, or until the operator issues the
DISASSOCIATE command.
asynchronous A method of transmitting data serially without
sending a clock signal. Each character consists of
one start bit, five to eight data bits, an optional
parity bit, and one or more stop bits. The
opposite of synchronous.
asynchronous I/O An I/O operation. The user process need not wait
for completion before continuing execution. There
are two forms, user asynchronous I/O and system
asynchronous I/O.
asynchronous serial A part of the fundamental operating software
communications (ASC) package for the 900 Series HP 3000. It works in
conjunction with the Datacommunications and
Terminal Controller (DTC) to provide data
transmission functions. The ASC software handles
handshaking between the host system and its
asynchronous devices, including character echoing,
multiplexing, and input character buffering.
attachment unit A cable joining the local area network interface
interface (AUI) controller (LANIC) to the media attachment unit
(MAU) for coaxial cable IEEE 802.3 local area
network links.
attributes Characteristics assigned to users, groups, and
accounts which determine what can be done in the
groups and accounts, or by the user. Attributes
include file access codes and special capabilities.
They enable the computer to determine what
functions it will or will not allow a user, group,
or account to perform.
authorization group A security feature of HP SQL. A collection of users
and groups with the same authorities within a
DBEnvironment.
automatic calling A device that automatically places a telephone call
unit (ACU) after receiving instructions from the calling
device.
automatic in A computer-to-PBX connection sequence. It allows
the computer to initiate an incoming connection on
a specified channel from a specified device through
the PBX. No telephone number is given; the device
location (telephone number) is associated with the
given channel by an administrative process on the
PBX.
automatic master A data set within a database. It contains only one
data set data item (the key item). It is related to at
least one detail data set. When a new search item
value is added to a related detail set, a new entry
is automatically added to the master with that item
value as a key. When the last entry containing
that search item is deleted from all related child
data sets, the master entry is automatically
deleted.
automatic out A computer-to-PBX connection sequence. It allows
the computer to initiate an outgoing connection on
a specified channel to a specified device through
the PBX. No telephone number is given; the device
location (telephone number) is associated with the
given channel by an administrative process on the
PBX.
automatic restart Main memory battery backup to automatically restart
the system after a power failure. Temporary power
line interruptions can be tolerated with no data
loss and without needing to restart the system.
backplane Wiring blocks or units that provide most of the
interconnecting circuits of a system. Individual
printed-circuit boards plug into the backplane.
Every backplane contains multiple card cages.
backreference The technique of using an asterisk (*) before a
formal file designator to indicate that it has been
previously defined with the FILE command.
backup The process that duplicates computer data to
offline media, such as magnetic tape. Backups
protect data if a system problem should occur.
backup devices System peripherals that allow you to write
information to, and read information from, backup
media.
battery backup unit A box within the SPU that contains a battery to
supply power to main memory during a power failure.
BASIC Beginner's All-purpose Symbolic Instruction Code.
A computer programming language.
batch processing A method of submitting a job for processing. A
job, which is submitted as a single entity, can
consist of multiple commands such as program
compilation and execution, file manipulation, or
utility functions. Once submitted, no further
interaction between the user and the job is
necessary.
batch access A default capability. It is assigned to accounts
capability (BA and users, allowing users to submit batch jobs.
capability)
baud A measure of the speed at which information travels
between devices. This signal speed is equal to the
number of discrete conditions or signal event
changes per second. When one bit represents each
signal change, baud is the same as bits per second.
Terminal speed settings are the most familiar
references to baud rate.
beginning of tape A mark on a magnetic tape indicating where the tape
(BOT) drive will start reading or writing data.
beta test The designation given to a product test in a
limited customer environment. For example,
Hewlett-Packard tests its products at selected
external customer sites before they are publicly
released.
binary A method of representing numbers, alphabetic
characters, and symbols in digital computers.
Binary is the base two numbering system that uses
only two digits, 0's and 1's, to express numeric
quantities.
binary coded decimal A decimal notation in which individual decimal
(BCD) digits are each represented by a group of four
bits.
binary synchronous A data link protocol, also referred to as BISYNC. A
communications (BSC) line control station in a data communications
system.
bit A binary digit; the number 0 or 1 in the base 2
numbering system (0 represents OFF, and 1
represents ON). Usually eight bits equal one byte.
A bit is the smallest unit of information in a
digital computer.
bit bucket Computer jargon referring to a nonexistent computer
storage area. The bit bucket is used when the
system-defined $NULL file is specified in a command
line as an output file. The associated write
request is accepted by MPE/iX, but no physical
output is actually performed.
bit-oriented A communications protocol that does not recognize a
protocol (bop) character as sequences of bits.
bit rate The speed at which bits are transmitted. The bit
rate is usually kilobits per second (Kb/s) or
megabits per second (Mb/s).
bits per inch (bpi) A measurement of data density. It expresses the
number of bits recorded per inch of recording
surface.
bits per second A measure of transmission speed over a
(bps) communications channel.
block A group of one or more logical records treated as a
single piece of data.
blocked A state of suspension for a process.
blocked record A physical record that contains more than one
logical record. The opposite of unblocked record.
block mode A terminal processing mode. It transmits groups,
or blocks of characters all at once, instead of one
character at a time.
board A piece of fiberglass that holds integrated
circuits (ICs or chips) and contains the
connections between chips. A board is also called
a card or circuit board.
Boolean A data type with a value that is either TRUE or
FALSE (binary 1 or 0).
boot The process of loading and initializing an
operating system. The term booting is derived from
the phrase "pulling yourself up by your
bootstraps."
boot path Boot paths are used to bring up the system from
disk or tape. The primary boot path is used for
booting the system from disk resident software.
The alternate boot path is used for booting the
system from a boot tape. The console boot path is
used to determine if the system can autoboot
without operator intervention.
boot ROM Performs tests on the computer's hardware, finds
all devices that are accessible through the
computer, and then loads either a specified
operating system or the first operating system
found according to a specific search algorithm.
boot tape A tape created by backing up the system with the
system generator (SYSGEN) utility program. The
tape is then used to reload the system. Also
referred to as a system load tape. Equivalent to
MPE V/E coldload tape.
bottleneck A system resource that is being completely used and
is compromising system performance.
branch A machine instruction that alters the sequence of
instructions being executed by the CPU.
break 1) An operation that interrupts (suspends or
aborts) an executing process and allows the user to
initiate some other operation.
2) To press the Break key on the terminal or call
the CAUSEBREAK intrinsic. If a process is only
suspended, it may be resumed with the RESUME
command.
broadcast A communication method of sending a message to all
devices on a link simultaneously.
broadcast bus A network in which nodes are connected by a linear
network run of cable. Messages are simultaneously
transmitted to every node. Typically, the nodes
process only those messages addressed to them and
ignore all other messages. The opposite of
point-to-point network.
broadcast space An implementation to address multiple processors on
a bus. Local broadcast address space is used when
all processors on a bus with the I/O module are to
be interrupted. A global broadcast address space
is used when all processors system-wide are to be
interrupted.
b-tree index An index type supported by DBCore that maintains
tuples in sorted order by key value and is used for
accessing a particular tuple in a set of tuples.
buffer The part of a computer or device memory where data
is held temporarily until it can be processed or
transmitted elsewhere. A buffer usually refers to
a memory area that is reserved for I/O operations.
bug Computer industry jargon for a computer problem.
bundled systems A pricing option. It allows a group of products to
be purchased at a lower cost than if they were each
purchased separately.
bus A common group of hardware lines that are used to
transmit information between digitally based
devices or components.
bus address A number that is part of the address used to find a
particular device. The bus address is determined
by a setting on a peripheral device that allows the
computer to distinguish between two devices
connected to the same interface. A bus address is
also referred to as a device address.
BYE An MPE command used to terminate an interactive
session on the HP 3000.
byte A combination of eight consecutive bits treated as
a unit. A byte represents one letter or number.
The size of memory and disk storage is measured in
bytes.
bytes per inch (BPI) A measurement of data density; usually for tapes.
It expresses the number of bytes recorded per inch
of recording surface.
C A high-level computer programming language that can
do low-level manipulations. It allows great
flexibility with type declarations.
cable A connector between computers and peripheral
devices.
cache A small, high-speed memory buffer unit. The cache
is continually updated to contain recently accessed
data to reduce access time. There may be one cache
or separate caches for instructions and data. HP
Precision Architecture has separate caches.
cache miss When an instruction or data required by the CPU is
not stored in a cache, the procedure that occurs is
called a cache miss. The required code or data is
then retrieved from the main memory modules.
capability A type of access right assigned to a subject (user,
group, or account) affecting what the subject can
do to an object (file, device, command) on the
system.
card A printed circuit assembly (PCA). See board.
card cage The structure used to hold cards in their proper
place inside the computer. Card cage and I/O bay
are sometimes used interchangeably. However, the
I/O bay usually refers to the entire cabinet
containing one or more card cages used to store the
cards that control I/O devices.
card image The representation of data in the standard columns
found on a punched card, which is a fixed-length
record of 80 characters.
carriage-control Carriage-control characters determine such things
characters (CCTL) as double spacing, vertical line spacing, and page
ejects.
catalog A file that acts as a directory of specific objects
(files, commands, messages, users, etc.) on the
system.
catenet Several networks that are joined, or concatenated,
to form a network of networks. A catenet is also
called an internetwork.
cathode ray tube The video display part of a terminal or PC.
(CRT)
CCITT Comite Consultatif International Telephonique et
Telegraphique (International Telegraph and
Telephone Consultative Committee); an international
standards group for establishing communication
protocols.
central bus (CTB) The communication path between the CPU main memory
modules and the channel I/O adapters.
central processing The part of a system that interprets and executes
unit (CPU) machine instructions. The central processor
contains an execution unit and a control unit. See
also SPU.
channel A path within a data communications line through
which data flows.
channel I/O (CIO) Input/output instructions for a channel.
channel I/O adapter Provides the interface between the central bus
(CTB) and the channel I/O buses. Each channel I/O
adapter serves as a high performance channel
multiplexer. It provides a full direct memory
access (DMA) for all HP-IB and LAN I/O channels and
synchronizes the differing speeds and bandwidths of
the CTB and channel I/O buses.
channel I/O buses Provides a synchronous bidirectional data path
(CIB) between the central bus (CTB) and I/O devices.
channel number The number assigned to the device controller board
in the I/O card cage. It is used to calculate the
logical address of the device, or device reference
table (DRT) number.
character A letter, number, or symbol represented by one byte
of data.
character-oriented A communications protocol that uses special control
protocol
characters to relay instructions for controlling
data transmission.
character set A series of characters to substitute for a single
character to name a group of files.
characters per inch A measurement of print density of various printers.
(cpi)
checksum The combination of all binary digits in a block.
The checksum is used to verify correct transmission
of the block.
child process A new process created by an existing process. The
new process is thereafter known to the preexisting
process as its child process. The preexisting
process is called the parent process.
chip A slice of silicon containing an integrated
circuit. RAM, ROM, PROM, CPU, and EPROM are
commonly used chips.
CIO adapter (CA) The interface slot number containing the adapter
for the CIO bus and central bus (CTB).
CIO expander The channel input/output expander provides eight
additional peripheral card slots to the SPU.
circuit board See board.
circular file 1) A wraparound file structure that functions as a
sequential file until it is full. As records are
written to a circular file, they are appended to
the tail of the file. When the file is full, the
next record causes the block at the head of the
file to be deleted and all other blocks to be
logically shifted toward the head of the file.
Circular files are useful as history files when you
are more interested in information recently written
to the file and less concerned about earlier
material.
2) A file that can be reused (DBCore nonarchive log
files are circular files).
class A user-defined collection of objects.
class name 1) A label that is either unique to, or associated
with, one or more devices in the system's I/O
configuration, used to reference a particular
device or class of devices. Device class names may
be up to eight alphanumeric characters long,
beginning with a letter. A single logical device
may have multiple device class names. The HP 2680
Laser Printer, for example, is referred to as EPOC
(electro-photographic output for computers), PP
(page printer), or SLP (system line printer), or
any other defined name. Directing output to any of
these class names sends the output to a laser
printer.
2) An abstract entity that can own objects in an HP
SQL DBEnvironment.
clipping To restrict plotting or drawing to a rectangular
portion (window) of the total available area.
closing a file Terminating access to a file. A file is closed by
calling the FCLOSE intrinsic or terminating process
execution.
cluster A physical storage organization method supported by
DBCore that can help minimize disk accesses. If a
relation is clustered, the physical placement of
its rows is controlled by a key value; this key is
called the cluster index key.
COBOL Common business-oriented language. A high-level
computer language primarily used for business
applications.
code Code consists of the executable instructions that
make up a program or subprogram.
code segment The instructions to the CPU contained in a single
logical module; one or more code segments comprise
a complete program or subprogram. Code segments
remain unchanged during program execution, and may
be overwritten with a new code segment once the
current segment has executed completely. In this
way, programs larger than the maximum code segment
size can execute without user intervention or a
large amount of memory.
code segment table A table that keeps track of all code segments
(CST) currently being used. CST is used only in
compatibility mode (CM) on MPE
XL.
cold dump See memory dump.
coldload See system load tape.
coldload tape See boot tape.
COLDSTART See UPDATE.
color palette In plotting terminology, a specific set of pen
colors and line widths as defined by the pen color
instructions of the graphics system being used.
column A named collection of data in an HP SQL table or
view with a particular data type and size.
command A system-reserved word that directs the operating
system, a subsystem, or a utility program to
perform a specific operation.
command file 1) A set of one or more MPE/iX commands in a file
that are executed by specifying the file name. See
also HPPATH or UDC.
2) A set of one or more SQL or ISQL commands in a
file that can be executed with the ISQL START
command.
command interpreter CI: A program that reads command lines entered at
(CI)
the standard input device, interprets them,
determines if they are valid, and, if so, executes
them.
command line history See history stack (also called command history
stack stack).
command set '80 A family of mass storage devices from
protocol (CS/80 or Hewlett-Packard that communicate using the C/80
CS-80) protocol. Examples are the HP
7911, HP 7912, HP 7914 disk/tape drives.
communication The ability of one computer system to access or
talk to other computer systems by way of
telecommunication devices.
communication link The software and hardware that moves data from the
driver and card of one computer to the driver of an
adjacent computer.
communications Allows users to obtain exclusive access to a
subsystem capability communications device such as a DSN/RJE line or a
(CS) DSN/DS line. The capability is required to use
DSN/RJE subsystems.
compatibility The ability of software developed for one computer
to work on another computer. See compatibility
mode.
compatibility mode Compatibility mode provides object code
(CM) compatibility between MPE V/E-based systems and the
900 Series
HP 3000. Compatibility mode allows current
Hewlett-Packard customers to move applications and
data to the 900 Series
HP 3000 without changes or recompilation.
compile The process of changing a program written in a
source language (for example, BASIC, C, FORTRAN)
into machine executable instructions. The compiled
routine is then ready to be link-edited and then
loaded into storage and run.
compiler A program that translates source code written by a
programmer into machine instructions. The compiler
also diagnoses and reports syntax errors found in
the application program.
completion list A linked list of four-word entries made by a direct
memory access (DMA) I/O card before interrupting
the processor. Each DMA adapter or module (which
may have more than one DMA device associated with
it) has its own completion list.
complex instruction A computer based on an architecture that uses
set computer (CISC) microprogramming and complex instructions.
component name A name identifying an object within the context of
a directory object.
compound item A named group of identically defined, adjacent
items within the same data entry; an array. A
compound item is subdivided into subitems.
compression The process of translating data into a more compact
form so that it can be transmitted more
economically or efficiently.
computer A device that accepts information, processes it,
and supplies an output. A computer usually
contains memory, a control unit, arithmetic and
logical units, and a means for input and output.
concurrent A decentralized system directory scheme. Each disk
directories attached to the system contains its own directory
of the files on that disk. This provides faster
file access by eliminating the physical or logical
serialization of a centralized directory.
configuration 1) The way in which computer and peripheral devices
are programmed to interact with each other.
2) The layout of the computer system, including MPE
table, memory, and buffer sizes. The configuration
tells which peripheral devices are connected to the
computer and how they can be accessed. The system
is configured by the system supervisor, who works
with the Hewlett-Packard applications engineer
(AE).
connect time The amount of time, in minutes, that a user, group,
or account has used the CPU for a session or job.
It is determined by executing the MPE REPORT
command.
console A terminal given unique status by the operating
system. The operator uses the console to monitor
and manage jobs, sessions and resources, respond to
requests, and communicate with other user
terminals. It is used to boot the system and
receive system loader error messages, system error
messages, and system status messages.
console boot path Used to determine if the system can autoboot
without operator intervention. See boot path.
console command A command that is executable only from the system
console at the = prompt (generated by pressing CTRL
and the A key on the console keyboard). Console
commands cannot be distributed to MPE users, since
CTRLA has no meaning on a standard terminal. The
logical console, however, can be moved to a
standard terminal.
console logging A system logging event. It records console
commands in the system log file.
console message A message sent to the system console by the system,
an application, or a user.
constant A fixed value (as opposed to a variable which is a
symbol for a changing valuex)..
continuation An ampersand (&) character entered as the last
character character of a command line. A continuation
character tells the command interpreter that the
command is longer than one line and is continuing
onto a second or more subsequent lines.
continuation line See subline.
control character A member of a character set that produces action in
a device rather than printing or displaying a
character. In the ASCII character set, control
characters are those in the range 0 through 31, and
127. Control characters are generated by pressing
the CTRL key and a character key simultaneously
(for example D). In documentation these two-key
sequences are shown as CTRLD.
control codes Special codes contained in data sent to a
peripheral device. These codes control how the
device operates.
control program The program responsible for handling I/O for
terminals and file storage, establishing processing
priorities, maintaining waiting lists of work in
process, activating operational programs, and
performing other supervisory functions in a
real-time system. Other terms used synonymously to
designate such a program are driver, executive,
monitor, kernel, and supervisor.
control register A 32-bit register on the register file board, used
for memory access protection, interrupt control,
and processor state control.
control unit A part of the CPU that regulates the execution unit
and oversees the instruction cycle.
control-Y A break function activated by simultaneously
pressing the CTRL key and the Y key on a terminal's
keyboard. It is typically a subsystem break and
does not affect MPE commands. In documentation
this two-key sequence is shown as CTRLY.
COOLSTART See START.
coprocessor A special purpose processor that works with the CPU
to speed up specialized operations such as
floating-point arithmetic and graphics processing.
coupled environment The MPE/iX file system's use of the MPE V/E file
system in compatibility mode to perform functions
that MPE/iX does not currently handle.
CPU time The amount of time, in seconds, that a user, group,
or account has used the CPU. It is displayed by
executing the MPE REPORT command.
crash 1) The unexpected shutdown of a program or system.
If the operating system crashes, it is called a
system crash, and the system must be rebooted.
2) A head crash or disk crash. This occurs when
the read/write heads on a disk drive (that normally
ride on a thin cushion of air above the disk) make
physical contact with the disk surface, destroying
data and the disk track. The extent of damage to
the system depends on which disk crashed and how
much of the disk was corrupted. A crash of the
system disk is serious, since it contains the
directory of user files as well as operating system
programs, the I/O configuration, and the account
structure.
CRC-CCITT An error detection scheme defined by the Comite
Consultatif International Telephonique et
Telegraphique (CCITT).
CRC-16 An error detection scheme used in data
communications.
create volumes The ability to define and access nonsystem domain
capability (CV disks with the NEWSET command of VOLUTIL.PUB.SYS
capability) (use NEWVSET command for private volumes on MPE
V/E). Users and accounts assigned CV capability are
automatically given use volumes (UV) capability.
cursor 1) A flashing rectangle or blinking underline
character on a display screen. It marks the
position where text or data can be entered,
changed, or deleted.
2) In HP SQL, the pointer to one tuple in a set of
tuples from an application program.
customer engineer A Hewlett-Packard field representative responsible
(CE) for the installation, troubleshooting, and
maintenance of computer hardware and operating
systems.
custom performance Using an outside performance expert to locate and
consulting evaluate performance problems.
cyclic redundancy An error detection scheme in which the checking
check (CRC) character is generated by taking the remainder
after dividing all the serialized bits in a block
of data by a predetermined binary number. An equal
comparison indicates no errors, while an unequal
comparison indicates an error in the transmission.
cylinder A portion of a disk pack that consists of
vertically aligned tracks on each disk platter
within the pack. The first track on the first
platter is directly above the first track on the
second platter, which is aligned with the first
track on the third platter, and so on. These
tracks, taken together, are considered a cylinder.
Therefore, cylinder 1 refers to track 1 on each of
the platters in the disk.
daisy wheel printer A printer that forms characters by striking metal
or plastic images of characters against a ribbon
onto paper. The name comes from the shape of the
print wheel, which looks like a daisy.
database (DB) A collection of logically related data files, and
structural information about the data and/or files.
database management A software package designed to protect the
system (DBMS) consistency and security of data in computer-stored
files (databases). It allows a user to define a
database structure and manipulate the contents by
storing, retrieving, deleting, modifying, and
sorting data.
data cache A high-speed CPU cache implemented on the 900
Series
HP 3000. It operates in parallel with the
instruction cache. Data is transferred by load and
store instructions between the general purpose
registers of the execution unit and the data cache.
It is a write-to cache, so the main memory modules
are updated only as required. See instruction
cache.
data circuit Equipment used to send information between
terminating locations, such as a modem. DCE is also known as
equipment (DCE) data communications equipment.
data communications The transmission of information from one computer
or terminal to another. It is sometimes shortened
to datacomm.
Datacommunications An MPE/iX intelligent controller, with
and Terminal microprocessors to handle communications with 900
Controller (DTC) Series HP 3000 systems. Each DTC may contain
connection cards allowing access to X.25 networks,
as well as connection cards allowing asynchronous
device connections.
data communications The methodology used to connect all asynchronous
and terminal devices to a 900 series HP 3000, except for the
subsystem (DTS) system console.
data dictionary A database used as a programmer's tool to store
information about data. It does not contain the
data itself, but describes the type, location,
usage, and relationships of the data resources of
an organization.
data endpoint The point at which the digital multiplexer
interface (DMI) data channel protocol is
terminated. Data endpoints can be at the host
computer or at the PBX. Data endpoints are
classified by the physical serial interface they
would present such as terminal or communication
equipment. See data circuit-terminating equipment
and data terminal equipment.
data entry A task that involves entering information into a
computer.
data item The smallest accessible data element in a database.
A data item corresponds to a column in relational
database terminology.
data link layer Layer two of the Open Systems Interconnection (OSI)
network model. The data link layer checks for and
corrects transmission errors over the physical
link.
data recovery The process of using special utilities to recover
data that cannot be used by the operating system
from disks (due primarily to disk addressing
problems).
data segment table A table that identifies and provides pointer
(DST) information to all data segments, including those
used by MPE and user's data stacks. On the 900
Series HP 3000 the DST is used only in
compatibility mode (CM).
data set A file used in a database. There are different
types of data sets: detail, manual master, and
automatic master.
data switch A dynamic port allocator. Allows access from any
terminal to any system that is connected (see PBX).
data terminal The local node or the user terminal where
equipment (DTE) information enters into and exits from a data link
or the computer itself.
DBCore/XL The common services that HP SQL uses on the MPE/iX
operating system.
DBEFile The basic unit of storage used by DBCore. A
DBEFile is a file on the host operating system.
DBCore stores relations in DBEFileSets.
DBEFileSet A logical grouping of DBEFiles. A relation can
span DBEFiles within a DBEFileSet.
DBEnvironment (DBE) The scope of transactions and recovery for HP SQL
databases. A DBE is a collection of one or more
databases.
deadlock A condition that arises when multiple processes are
waiting for resources held by other processes. A
process cannot release the resources it holds until
it can acquire the resources it is waiting for, but
it cannot acquire these resources until another
process releases them.
debug 1) To find and correct mistakes in a computer
program.
2) Debug/XL is the debug facility supplied with
MPE/iX. It provides debug information at the
machine instruction (object code) level. It can
be used to debug programs written in any
Hewlett-Packard-supported language, both in native
mode and compatibility mode.
decimal code The decimal representation of an ASCII character.
For example, the character A has the ASCII binary
code value 01000001 and the decimal code value 65.
default A predefined value or condition that is assumed,
and used if no other value or condition is
specified.
defined volume A member volume that is not yet physically
available to a volume set, but has its name, class
assignments, and space allocation specified on the
volume set information table (VSIT) of a system
master volume. See initialized volume.
delimiter A special character used to mark the end of a
string of characters. Common delimiters are a
comma (,), semicolon (;), equal sign (=), or a
Return.
delta A term used to express an incremental change.
Refers to a release of the operating system with
only minor changes from the previous release.
dereferencing Dereferencing substitutes the value of a variable
in place of the variable name. See also explicit
dereferencing and implicit dereferencing.
descriptor A set of data structures that collectively
represent the characteristics of an open file. The
data structures contain the file's attributes,
identification, access control, and accounting
information, and are maintained by the file system
routines.
destructive testing A deliberate attempt to cause the system or program
to fail by including a test specifically designed
for that purpose.
detail data set A data set in a database whose entries contain one
or more search items but not a key item. Entries
with the same search item value are chained
together; this chain can be linked to entries in
master data sets that have matching key item
values. A detail data set is equivalent to a child
relation that does not have a key item.
device See peripheral.
device adapter A device that manages communications between the
computer and a peripheral device. It is the same
as an I/O interface card or a printed circuit
assembly.
device address See bus address.
device class A collection of devices. The MPE/iX file system
supports a means of maintaining collections of
devices.
device configuration See system configuration.
device file A physical device that the system treats as a file
by writing to it or reading from it. Examples of
device files are $STDIN and $STDLIST, the default
input and output device files for the keyboard and
terminal screen, respectively.
device independence A characteristic of the operating system that
allows users to selectively redirect input/output
from a program, session, or job with the FILE
command without regard to the nature of the device.
File equations created with the FILE command are in
effect only for the duration of the job or session
in which they are defined.
device reference A table containing the logical address of disks,
table (DRT) tape drives, and other peripheral devices.
device subtype A number ranging from 0 to 15, defining a specific
device and its associated software driver. There
can be several device subtypes within one basic
type. For example, a graphics terminal and one
without graphics capabilities can share the same
device type, but they are assigned different
subtype numbers.
device type Device types are defined by a number. For example,
0 represents a moving-head disk and 16 is the class
type number assigned to line printers.
diagnostician A capability usually assigned only to the
capability (DI Hewlett-Packard customer engineer (CE). It allows
capability) the CE to conduct certain CPU and diagnostic tests.
Diagnostic Support The online diagnostic package for the Intelligent
Monitor (DSM) Network Processor (INP).
diagnostic user A means by which a user can communicate with the
interface (DUI) diagnostic system.
diagnostic utility A set of utilities used to diagnose a system
system (DUS) failure. The DUS is loaded from standalone serial
storage media into the main memory of the shutdown
system.
diagnostics A set of programs that test for hardware faults.
dibit A two-bit signal unit.
digital A method of representing all information stored,
processed, or transferred in discrete values or
symbols. For example, the set of integers
constitute a set of digital values. The opposite
of analog.
digital multiplexed A specification for interfacing a host computer to
interface (DMI) a private branch exchange (PBX).
digitize To convert a continuous function to one containing
a finite number of discrete levels.
direct access To read from or write to a random access device
(usually a disk) by addressing a specific logical
record. Direct record access is not possible on
serial storage media (such as magnetic tapes) since
data can only be read sequentially from the first
record (or byte) to the nth record (or byte).
direct connect modem A data communications device. A direct connect
modem has a built-in phone jack, allowing the phone
line to be plugged directly into the modem. The
opposite of acoustic modem.
direct memory access A technique that allows a periperals device to gain
(DMA) direct access to the main memory of the computer.
This method allows extremely high data transfer
rates.
directory A system table showing in what group or account
each file is located, as well as its disk address,
so that it can be accessed. A directory may
contain other information such as size of the file,
its creation date, any modification dates, file
creator, or file security information.
DISCFREE An MPE/iX utility supplying information about a
system's disk free space, transient and permanent
space, and the volumes total space capacity. The
information is supplied in either a histogram or a
condensed format. Equivalent to the MPE V/E FREE5
utility.
DISCUTIL utility An MPE/iX utility that is used primarily to recover
data from disks that cannot be used by the
operating system.
disk A circular plate, coated with material which holds
a magnetic charge, used to store computer data. A
disk may be fixed, removable, hard, or flexible.
disk drive A peripheral device that reads information from and
writes information to the disk.
disk failure A disk-related problem that causes a disk to be
unavailable for use.
disk file A file stored on disk.
disk I/O The electromechanical process of transferring the
code and data that are stored on disk into main
memory.
disk loaded See mounting.
disk pack A set of one or more disk platters stacked inside a
plastic cylindrical container.
disk platter An aluminum disk coated with magnetic material.
One or more platters are mounted on a central
spindle, and together they form a complete disk
pack. Information may be recorded on one or both
sides of each platter within the pack.
disk sector A section of a disk's surface (256 contiguous
bytes). A file is stored in one or more sectors.
disk space The space available on a disk to store data.
disk status The state of a disk recognized by the system. See
MEMBER, MASTER, LONER, SCRATCH, and UNKNOWN.
disk swapping The process of moving data segments from memory to
disk and from disk to memory; and for moving code
segments from disk to memory.
diskette See flexible disk.
dismounted A disk not recognized by the system.
distributed database A database whose data is located on a number of
different computers, which may be in different
geographic locations.
distributed systems Systems in which some or all of the processing
functions are in different places and connected by
transmission facilities.
distributed system The communications line between two computers,
line (DS line) controlled by the distributed system network.
distributed system A system of hardware and software data
network (DSN) communications products spanning multiple
Hewlett-Packard product lines.
dot matrix printer A printer in which each character is represented by
a pattern of dots.
download The process of transferring a block of information
from one computer system to another.
driver 1) In hardware, driver refers to a circuit that is
capable of supplying specific current and voltage
requirements.
2) In software, driver refers to a program that is
capable of controlling a specific input/output
device. See control program.
DRT number Device reference table number. The physical I/O
address of a device controller, displayed in the
second column of the I/O configuration table listed
during the SYSDUMP dialog. An MPE V/E index into
the DRT.
dumb terminal A terminal which can only display and transmit
data.
DUMP 1) The MPE/XL ISL DUMP utility writes system main
memory and secondary storage to tape. DUMP also,
optionally, attempts a software reboot from disk.
2) See cold dump.
Dump Analysis (DPAN) See dump analysis tool (DAT)
Dump Analysis Tool An MPE/iX program. It produces a formatted listing
(DAT) of the contents of main memory after a system
failure or shutdown. This aids in the analysis of
fatal system events such as process hangs, system
failures, or hardware failures. This tool is
similar to the MPE V dump analysis program (DPAN).
duplex The method of transmission that allows simultaneous
two-way communication. Duplex is usually called
full-duplex. The opposite of half-duplex.
duplicative 1) To echo input operations to a corresponding
display without intervention by the operating
system software.
2) The name of an MPE/iX command that writes to
$STDLIST.
dynamic backup Dynamic backup means that the STORE file set and
structures are accessible for any access while the
backup is taking place. Any modifications made to
the STORE file set during the backup are logged and
saved along with the data on the backup medium. On
RESTORE, the data and log file are used to recover
the data to a consistent state.