IBM S/390 Reference Manual page 20

Channel-to-channel (CTC).
Refers to the communication (transfer of data) between
programs on opposite sides of a channel-to-channel
adapter (CTCA).
CMOS (Complementary metal-oxide semiconductor).
An electronic circuit definition and packaging technol-
ogy that uses considerably less power than other types
of semiconductors.
Concurrent hardware maintenance.
Allows the replacement of a failing unit without powering
off the system. This function enhances the processor
availability, since no system outage is required for the
repair action. Concurrent maintenance capability exists
on the following:
• HDDs
• Power Elements
• Thermal Elements
• Hardware Management Console
Concurrent Licensed Internal Code (LIC).
Allows the activation of a patch concurrent with the sys-
tem operation, therefore further increasing the availabil-
ity of the processor. This capability exists on the
following:
• LPAR Code
• CP Code
• ESCON Channels
• Parallel Channels
• Power Control
• Hardware Management Console Code
• SAP Code
Console integration.
The Hardware Management Console can also be used
as an operator console. If operations are sufficiently
automated (for example, through NetView
allow installations to eliminate or reduce the need for
non-SNA consoles and supporting cluster controllers.
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Data compression.
A hardware facility to reduce the processor time
required to compress data. For DASD storage, space
savings can be in the range of 40-50% for supported
data types. For communication lines, this facility can
improve the response time for transmitting bulk data.
Other benefits can include reduced channel utilization,
reduced processor storage for DASD data buffers, and
so on. Hardware-assisted compression can provide
about a five-times reduction in processor time com-
pared to software-based compression.
Data sharing.
The ability of concurrent subsystems (such as DB2 or
IMS™ DB) or application programs to directly access and
change the same data while maintaining data integrity.
DB2 sort assist.
A combination of enhancements to hardware and soft-
ware that can provide up to a 37% reduction in elapsed
time and up to a 62% reduction in CPU time for DB2
queries using sort.
Dual power feeds.
There are two input power lines. An installation can
enhance availability by connecting these feeds to
independent power sources.
Dyadic processor.
A two-way multiprocessor that uses two central proces-
sors for instruction execution while sharing central stor-
age and channels.
Dynamic memory sparing.
A memory chip is dynamically invoked when another
memory chip fails.
Dynamic reconfiguration management.
Provides the capability to dynamically add, delete or
modify the I/O configuration for channel paths, control
units and I/O devices without Power-On-Reset (POR) or
Initial Program Load (IPL).
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