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

20 Chapter1
Glossary of Terms
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.