System Startup, Configuration, and Shutdown Reference Manual (32650-90892)

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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.
extent A group of one or more contiguous sectors on a volume used to allocate permanent
disk space. Extents can be variable length; any number of extents can exist for a given file.
file A group of related records that represents ASCII text (text files) or binary data (such
as executable code). Every file must have a file name so the user can access the file's
contents.
file code A four-digit integer that identifies the special function of a file. Users can assign