MPE/iX Glossary of Terms and Acronyms (32650-90887)

42 Chapter1
Glossary of Terms
logon UDC A user-defined command (UDC) automatically executed at logon. Specified
with an OPTION LOGON statement within the UDC.
LONER A duplicate of a member volume currently online, or a volume recognized
by MPE/iX as a member volume but without a master volume online. The
VSCLOSE command puts all master and member volumes of a set in the
LONER state.
machine cycle The period of time required by a computer to perform the most
fundamental operation.
machine instruction The smallest resolvable piece of a code segment. Machine
instructions are used by the CPU to accomplish a single task, such as
moving an item of data to the CPU, moving it from the CPU to memory, or
performing a single calculation using data in the CPU.
machine language Binary code that is executable by the CPU. All programs must
eventually be translated into machine language before they can be
processed by the computer.
magnetic tape A data storage media that comes on reels.
mainframe computer A computer that generally has a large amount of memory and
operates at high-speed, servicing multiple users and/or batch jobs.
main memory The fast, volatile, random access storage containing all currently
executing code and data segments, including portions of the operating
system and any utilities in use.
maintenance word A protection word restricting access to certain utility functions of a
database. The creator can define a maintenance word for a database or a
database space with HPIUtil and SQLUtil.
management information systems (MIS) A system using equipment and certain
procedures to aid the managerial decision-making process.
manual master data set A data set in a database containing a key item and possibly
other data items. A manual master does not have to be linked to a detail
data set. Entries in a manual master data set must be explicitly added or
deleted (compare to automatic master data set).
mapped file The disk files that are mapped directly into the virtual address space
memory, bypassing the file system and I/O routines that other disk files
must use.
mapped file access A method of transferring data to/from a disk file by implicitly using
virtual pointers and primitive LOAD and STORE instructions, rather than
by explicitly reading/writing using file system primitives. Mapped files are
accessible by obtaining a pointer to the file that is mapped to the user's
address space.
MASTER The state of a disk recognized by the system as a master volume.
master data set A data set with one or more data items, one of which must be a key item.
A master data set is generally used as an index to one or more detail data
sets. The two types of master data sets are manual and automatic.