Hardware Reference
In-Depth Information
Bit
A contraction of 'binary digit'; a single digit in a binary number.
Boot
The name given to the process of loading and initializing an operating
system (part of the operating system is held on disk and must be loaded from
disk into RAM on power-up).
Boot record
A single-sector record present on a disk which conveys infor-
mation about the disk and instructs the computer to load the requisite operating
system files into RAM (thus booting the machine).
Buffer
In a hardware context, a buffer is a device which provides a degree of
electrical isolation at an interface. The input to a buffer usually exhibits a much
higher impedance than its output (see also 'Driver'). In a software context, a
buffer is a reserved area of memory which provides temporary data storage and
thus may be used to compensate for a difference in the rate of data flow or time
of occurrence of events.
Bus
An electrical highway for signals which have some common function.
Most microprocessor systems have three distinct buses; an address bus, data bus,
and control bus. A local bus can be used for high-speed data transfer between
certain devices (e.g. processor, graphics processor, and video memory).
Byte
A group of 8 bits which are operated on as a unit.
Cache
A high-speed random-access memory which is used to store copies of
the data from the most recent main memory or hard disk accesses. Subsequent
accesses fetch data from this area rather than from the slower main memory or
hard disk.
Central processing unit (CPU)
See
Processor
.
Channel
A path along which signals or data can be sent.
Character set
The complete range of characters (letters, numbers, and
punctuation) which are provided within a system. See also ANSI and ASCII.
Checksum
Additional binary digits appended to a block of data. The value
of the appended digits is derived from the sum of the data present within the
block. This technique provides the means of error checking (validation).
Chip
The term commonly used to describe an integrated circuit.
Chipset
The chipset is the name given to the two or more integrated circuits
which control the interface between the processor, RAM, I/O devices, bus
expansion, and adapter cards. Different chipsets provide support for different
processors and motherboard configurations.
CISC
The term CISC refers to a 'Complex Instruction Set Computer' - the
standard Intel family of CPUs all conform to this model rather than the alterna-
tive 'Reduced Instruction Set Computer' (RISC). There is much debate about
the pro's and con's of these two design methodologies but, in fact, neither of
these two contrasting approaches has actually demonstrated clear superiority
over the other. See also
RISC
.
Clock
A source of timing signals used for synchronizing data transfers within
a microprocessor or microcomputer system.
