DEC 4000 AXP Service Manual page 230

symmetric multiprocessing (SMP)
A processing configuration in which multiple processors in a system operate as
equals, dividing and sharing the workload. OpenVMS SMP provides two forms
of multiprocessing: multiple processes can execute simultaneously on different
CPUs, thereby maximizing overall system performance; and single-stream
application programs can be partitioned into multistream jobs, minimizing the
processing time for a particular program. Contrast with distributed processing.
symptom-directed diagnostics (SDD)
Online analysis of system errors to locate potential system faults. SDD helps
isolate system problems.
synchronization
A method of controlling access to some shared resource so that predictable,
well-defined results are obtained when operating in a multiprocessing
environment.
system backplane
One of two backplanes in the BA640 enclosure. CPU, memory, I/O, Futurebus+,
and power modules plug into this backplane. See also backplane.
system bus
The private interconnect used on the DEC 4000 AXP CPU subsystem. This bus
connects the B2001 processor module, the B2002 memory module, and the B2101
I/O module.
system disk
The device on which operating system software resides.
system fatal error
An error that is fatal to the system operation, because the error occurred in the
context of a system process or the context of an error cannot be determined.
system machine check
System machine checks are generated by error conditions that are detected
asynchronously to processor execution. Examples of system machine check
conditions include protocol errors on the processor-memory interconnect,
unrecoverable memory errors detected by the I/O module or other CPU, and
memory correctable errors.
Glossary–20