System Startup, Configuration, and Shutdown Reference Manual (32650-90907)

Glossary
device file
Glossary
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device file A file associated with a non shareable
device (a spool file). Input and output spool files are
identified by a number in the DFID (device file
identification) column of the SHOWIN and SHOWOUT
command displays. A device file can also refer to any
non-disk device, such as $STDIN and $STDLIST, the
default input and output device files for a terminal.
device independence A characteristic of the
operating system that allows users to selectively
redirect input or output from a program, session, or
job using 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 were defined.
device subtype A number ranging from 0 to 15
that defines 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 are
assigned different subtype numbers.
device type A number that defines a type of device.
For example, 0 represents a moving-head disk and
16 is the device type number assigned to line
printers.
diagnostician capability (DI Capability) A
capability usually assigned only to the
Hewlett-Packard customer engineer (CE). It allows
the CE to conduct certain CPU and diagnostic tests.
directory A system table showing the group or
account in which a file is located. 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 A utility that supplies information about
a system’s unused disk space, transient and
permanent space, and the volume’s total space
capacity. The information is supplied in either a
histogram or a condensed format. Equivalent to the
MPE V/E FREE5 utility.
disk A circular plate of magnetically coated
material 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 file A file stored on disk.
disk I/O The electromechanical process of
transferring the code and data that are stored on
disk to and from main memory.
disk pack A set of one or more disk platters stacked
inside a plastic cylindrical container.
disk sector A section of a disk’s surface. A file is
stored in one or more sectors.
distributed systems line (DS Line) The
communication line between two computers,
controlled by the distributed systems network.
distributed systems network (DSN) A system of
hardware and software data communications
products spanning multiple Hewlett-Packard
product lines.
distributed terminal controller (DTC) An
intelligent controller with microprocessors to handle
workstation connection preprocessing and
communications with the system.
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.
DUMP A utility program that writes the current state
of the system’s main memory and secondary storage
to tape for analysis. DUMP also, optionally, attempts
a software reboot from disk.
EXCLUSIVE access A restriction limiting file access
to one user at a time. EXCLUSIVE access is
particularly important during file updates, when two
or more people modifying the same record within a
file, at the same time, could destroy data consistency.
execute To carry out the instructions or to perform
the routine indicated by entering a command or
program name.
executing state The state of a job or session when
it is in progress. Other possible states are INTRO,
WAIT, EXEC*, and SUSP.