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

Chapter 1 61
Glossary of Terms
CPU usage. A lower subqueue priority indicates a higher priority for CPU
time.
subsystem That part of the operating system that performs specific functions for
applications (for example, IMAGE database management system).
supervisor See control program.
swapping See disk swapping.
switch subsystem The MPE/iX switch subsystem determines whether code is in native
mode or compatibility mode, and automatically switches between modes as
needed while an application is running.
synchronous A method of transmitting data using a clock signal to coordinate timing.
The opposite of asynchronous.
synchronous data link control (SDLC) The protocol used in a systems network
architecture (SNA) network to transmit data over a communications link.
SDCL is a bit-oriented protocol that transmits data in frames.
syntax The rules governing the structure of a language or instruction.
syntax error An error in an instruction due to a misspelled word, a missing character,
or improper punctuation.
SYS account A special account on the HP 3000, included with the system when it is first
installed. It contains all MPE files (stored in the segmented library),
supported subsystems, utility programs, and compilers.
system A group of one or more CPUs that communicate through buses without the
use of data communications software.
system asynchronous I/O A method of performing I/O whereby a process informs a
driver or subsystem that it wants to know when data has arrived or when
it is possible to perform a write request. The driver or subsystem
maintains a set of buffers through which the process performs I/O. System
asynchronous I/O frees the process's buffers upon return from the I/O
request.
system buffers Any buffer used by the system to send messages to the console.
system call An operating system kernel function available to the user through a
high-level language (such as COBOL, FORTRAN, or Pascal). Also referred
to as an intrinsic or a system intrinsic.
system catalog A file containing UDC information for each user and accounts using
UDCs on a particular system.
system configuration The process of defining for the operating system the current
physical layout and workload of a particular installation. The
configuration is typically modified when new terminals, another line
printer, or a disk drive are added. The system also may be reconfigured to
assign new class names to existing devices, change the size of the system
tables or virtual memory, modify system logging, or alter any other
configuration parameter.
system console The terminal, usually logical device 20, the system operator uses to