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bus
A parallel electrical pathway on the system board, connecting and
shared by the parts of a computer system (especially the CPU, its
support circuitry, memory, and expansion cards), used for
transmitting data or electrical power from one device to another.
Typically the lines in a bus are dedicated to specific functions, such
as control lines, address lines, and data lines. Different bus
architectures have different numbers and arrangements of these lines,
and different names (for example, ISA, PCI). The most useful way of
distinguishing bus architectures is by the number of simultaneous
data bits they can carry. The ISA is a 16-bit bus, while PCI is a 32-bit
bus.
bus master
The ability of an expansion card to control the bus without needing
intervention from the CPU.
byte
Group of eight contiguous bits. Frequently written as an eight-digit
binary number or a two-digit hexadecimal number. One letter of the
alphabet in ASCII code takes one byte.
C
cache
A special block of fast memory used for temporary storage of
frequently used data for quick retrieval. A memory cache, sometimes
called a cache store or RAM cache, is a portion of memory made of
high-speed static RAM (SRAM) instead of the slower and cheaper
dynamic RAM (DRAM) used for system memory. Memory caching
is effective because most programs access the same data or
instructions over and over. By keeping as much of this information as
possible in SRAM, the computer avoids accessing the slower DRAM.
The strategies for determining which information should be kept in
the cache constitute some of the more interesting problems in
computer science. See "write-back" and "write-through."
chassis
The metal frame to which the electronic components of the computer
(such as the system board, power supply, and drive bays) are attached
The chassis goes inside the part you see, which is variously called the
lid, enclosure, or system unit cover.
Glossary 7
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