Specifications

10
Appendix A Glossary
bandwidth 1) Generally, the measure of the
range of frequencies within a radiation band
required to transmit a particular signal. The differ-
ence between the lowest and highest signal fre-
quencies. The bandwidth of a computer monitor is
a measure of the rate at which a monitor can han-
dle information from the display adapter. The
wider the bandwidth, the more information the
monitor can carry and the greater the resolution.
2) to describe the data-carrying capacity of a given
communications circuit or pathway. The band-
width of a circuit is a measure of the rate at which
information can be passed.
bank The collection of memory chips or mod-
ules that make up a block of memory readable or
writeable by the processor in a single cycle. This
block, therefore, must be as large as the data bus of
the particular microprocessor. In PC systems, the
processor data bus (and therefore the bank size) is
usually 8, 16, 32, or 64 bits wide. Optionally, some
systems also incorporate an additional parity or
ECC bit for each 8 data bits, resulting in a total of
9, 18, 36, or 72 bits (respectively) for each bank.
Memory in a PC always must be added or removed
in full-bank increments. The number of memory
chips or modules that make up a bank varies with
the width of the memory in bits and the size of the
processor’s data bus. For example, a K6-2 processor
has a data bus that is 64 bits wide. If the mother-
board uses 72-pin SIMMs (which are 32 data bits
wide), a bank is two SIMMs. However, if the
motherboard uses DIMMs, which are 64 data bits
wide, a bank is one DIMM.
bar code The code used on consumer products
and inventory parts for identification purposes.
Consists of bars of varying thickness that represent
characters and numerals that are read with an opti-
cal reader. The most common version is called the
universal product code (UPC).
base-2 Refers to the computer numbering system
that consists of two numerals: 0 and 1. Also called
binary.
base address Starting location for a consecutive
string of memory or I/O addresses/ports.
base memory The amount of memory available
to the operating system or application programs
within the first megabyte, accessible in the proces-
sor’s real mode.
base pointer (BP/EBP/RPB) A 16/32/64-bit
Intel architecture processor register pointing to data
in a stack segment.
baseband transmission The transmission of
digital signals over a limited distance. ARCnet and
Ethernet local area networks use baseband signal-
ing. Contrasts with broadband transmission, which
refers to the transmission of analog signals over a
greater distance.
BASIC (Beginner’s All-purpose Symbolic
Instruction Code) A popular computer pro-
gramming language originally developed by John
Kemeny and Thomas Kurtz in the mid-1960s at
Dartmouth College. Normally, BASIC is an interpre-
tive language, meaning that each statement is
translated and executed as it is encountered, but it
can be a compiled language, in which all the pro-
gram statements are compiled before execution.
Microsoft Visual Basic, a popular development
environment for Windows, is not related to BASIC.
batch file A set of commands stored in a disk
file for execution by the operating system. A special
batch file called
AUTOEXEC.BAT is executed by DOS
each time the system is started. All DOS and
Windows batch files have a
.BAT file extension.
baud A unit of signaling speed denoting the
number of discrete signal elements that can be
transmitted per second. The word baud is derived
from the name of J.M.E. Baudot (1845–1903), a
French pioneer in the field of printing telegraphy
and the inventor of Baudot code. Although techni-
cally inaccurate, baud rate commonly is used to
mean bit rate. Because each signal element or baud
can translate into many individual bits, bits per sec-
ond (bps) usually differs from baud rate. A rate of
2,400 baud means that 2,400 frequency or signal
changes per second are being sent, but each fre-
quency change can signal several bits of informa-
tion. For example, 33.6Kbps modems actually
transmit at only 2,400 baud.
Baudot code A 5-bit code used in many types of
data communications, including teletype (TTY),
radio teletype (RTTY), and telecommunications
devices for the deaf (TDD). Baudot code has been
revised and extended several times. See also baud.
bay An opening in a computer case or chassis
that holds disk drives.
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