Page 108 - Electrical Engineering Dictionary

age v i by v o = v i d/(1 − d) and it can be printer faster than the data can be physically
controlled by varying the duty ratio d. Note printed. See also buffered input/output.
that the output voltage is opposite polarity to
the input. Also called a buck-boost converter, buffered input/output input/output that
up-down transformer or up-down converter. transfers data through a “buffer,” or tempo-
See also flyback converter. rary storage area. The main purpose of the
buffer is to reduce time dependencies of the
bucket a stable phase space area where data and to decouple input/output from the
the particle beam may be captured and accel- program execution. Data may be prepared
erated. An RF bucket is the stable region in or consumed at an irregular rate, whereas the
longitudinal phase space. The bucket width transfer to or from disk is at a much higher
gives the maximum phase error or timing er- rate, or in a burst.
ror at the RF cavity, which a particle may A buffer is used in “blocked files,” where
have, and still complete the whole accelera- the record size as seen by the user does not
tion cycle. The bucket height is the corre- match the physical record size of the device.
sponding limit on momentum error.
buffering (1) the process of moving data
bucket truck a motor truck equipped with into or out of buffers or to use buffers to
a shell or bucket at the end of a hydraulically- deal with input/output from devices. See also
operated insulated arm. A line worker stands buffer, buffered input/output.
in the bucket and is thus raised to gain access (2) in optics, material surrounding the
to overhead conductors. optical fiber that provides the first layer of
protection from physical and environmental
bucking fields See differentially com- damage. The buffering is usually surrounded
pounded. by one or more layers of jacketing material
for additional physical protection of the fiber.
buddy memory allocation a memory al-
location system based on variable sized seg- bug (1) an error in a programmed imple-
ments will usually allocate space for a new mentation (may be either hardware or soft-
segment from a free area somewhat larger ware). Bugs may refer to errors in correct-
than necessary, leaving an unallocated frag- ness or performance.
ment of the original space. In “buddy” allo- (2) a syntactical or logical error in a com-
cation, this fragment cannot be used until its puter program. A name attributed to early
adjacent allocated space is released. Buddy computers and electronic testing.
allocation reduces memory fragmentation by
ensuring that available areas cannot be re- built-in logic block observer technique
peatedly subdivided. that combines the basic features of scan de-
signs, pseudo-random test pattern genera-
Buff book See IEEE Color Books. tion, and test result signature analysis.

buffer a temporary data storage area in built-in self-test (BIST) special hard-
memory that compensates for the different ware embedded into a device (VLSI chip or
speeds at which different elements are trans- a board) used to perform self testing. On-
ferred within a system. Buffers are used line BIST assures testing concurrently with
when data transfer rates and/or data process- normal operation (e.g., accomplished with
ing rates between sender and receiver vary, coding or duplication techniques). Off-line
for instance, a printer buffer, which is neces- BIST suspends normal operation and is car-
sary because the computer sends data to the ried out using built-in test pattern generator

c
2000 by CRC Press LLC