PEEK Reference Manual

Glossary
PEEK Reference Manual — 529657-006
Glossary - 2
clock
clock. See processor clock or system clock.
clock averaging algorithm. An algorithm used by the operating system to keep the
processor clocks in a system synchronized.
CME. (1) See correctable memory error (CME). (2) The PEEK INTERRUPTS element that
reports CME interrupts. See also interrupt.
complex instruction-set computing (CISC). A processor architecture based on a large
instruction set, characterized by numerous addressing modes, multicycle machine
instructions, and many special-purpose instructions. Contrast with reduced
instruction-set computing (RISC).
control packets. Sequenced message transmissions.
core services. The portion of the operating system that consists of the low-level functions,
including interprocess communications; I/O interface procedures; and memory, time,
and process management. Contrast with system services.
correctable memory error (CME). A single-bit error in an addressable memory location, for
which the operating system compensates. Contrast with uncorrectable memory error
(UCME).
current priority. The priority of a process at this time.
destination control table (DCT). The NonStop operating system data structure that holds
information about every device and named process in the system. The DCT consists of
the named resource list (NRL) and the process-pair list (PPL). The DCT is replicated in
each processor.
dirty pages. Frames (physical pages) of memory that have been changed since they were
mapped. If the frame has a swap file, the frame must be written to the swap file before
the memory manager can make the frame available to another process.
disk page. A unit of virtual storage. In TNS, TNS/R, and TNS/E systems, a disk page
cont
ains 2048 bytes. Contrast with memory page.
DISP. The PEEK INTERRUPTS element that reports dispatch interrupt
s. See also interrupt.
dispatcher. An interrupt handler that sends interprocessor messages, manages
semaphores, calculates process execution time, and changes the active process.
dispatching. The task of making a process active.
element. A data structure consisting of a header immediately followed by data.
extended data
segment. An area of virtual memory used to contain data
. An extended
data segment is allocated with contiguous addresses and is treated programmatically
as a single object. The two types of extended data segments are selectable segments