Page 115 - Electrical Engineering Dictionary

cache line a block of data associated with calculate power flows before the advent of
a cache tag. electronic computers.

cache memory See cache. calibration the procedure of character-
izing the equipment in place for a particular
cache miss a reference by the processor measurement set-up relative to some known
to a memory location currently not housed in quantity, usually a calibration standard trace-
the cache. able to the National Institute for Standards
and Technology (NIST).
cache replacement when a “cache miss”
occurs, the block containing the accessed lo- calibration kits designed for use with
cation must be loaded into the cache. If this vector network analyzers. With these kits
is full, an “old” block must be expelled from you can make error-corrected measurements
the cache and replaced by the “new” block. of devices by measuring known devices
The “cache replacement algorithm” decides (standards) over the frequency range of in-
which block should be replaced. An example terest. Calibration standards include shorts,
of this is the “Least Recently Used (LRU)” open, sliding, and fixed loads.
algorithm, which replaces the block that has
gone the longest time without being refer-
calibration standards a precision de-
enced.
vice used in the process of calibrating an EM
measurement system. It can be a standard
cache synonym See cache aliasing.
gain horn, an open, a short, a load, sphere,
etc., used to characterize an RCS, antenna,
cache tag a bit field associated with or transmission line measurement system.
each block in the cache. It is used to de- Most calibration standards are provided with
termine where (and if) a referenced block re- documentation that can be traced to a set of
sides in the cache. The tags are typically standards at the NIST.
housed in a separate (and even faster) mem-
ory (the “tag directory”) which is searched
call instruction (1) command within a
for in each memory reference. In this search,
computer program that instructs the com-
the high order bits of the memory address
puter to go to a subroutine.
are associatively compared with the tags to
determine the block location. The number (2) an instruction used to enter a subrou-
of bits used in the tag depends on the cache tine. When a call instruction executes, the
block “mapping function” used: “Direct- current program counter is saved on stack,
mapped,” “Fully associative,” or the “Block- and the address of the subroutine (provided
set-associative” mapped cache. by the call instruction) is used as the new pro-
gram counter.
CAD See computer-aided design.
calorimeter a device used to determine
cage-rotorinductionmotor aninduction particle energies by measuring the ionization
motor whose rotor is occupied by copper or of a particle shower in a heavy metal, usually
aluminum bars, known as rotor bars, instead iron and lead.
of windings. Also commonly referred to as
a squirrel-cage induction motor. CAM acronym for content-addressable
memory or computer-aided manufacturing.
calculating board a single-phase scale See associative memory, computer-aided
model of a power system that was used to manufacturing.

c
2000 by CRC Press LLC