Specifications

G-1
Glossary
16550 UART - A high speed chip for controlling
serial ports. Although unnecessary for a mouse, it
is required for modems that are 14,400 baud or
faster.
486DX - A type of 32-bit CPU with a built-in
math-coprocessor and internal cache.
486DX2 - A 486DX CPU where the internal
speed of the CPU operates at twice the external
speed.
486DX4 - A 486DX CPU where the internal
speed of the CPU operates at three times the
external speed.
486SX - A 486DX CPU with no math-
coprocessor.
Asynchronous - Operations that do not require the
clocks of communicating devices to be coordi-
nated. See synchronous.
Baby AT - A standard system board size
measuring approximately 13.25” x 8.5”.
Bidirectional Parallel Port - A type of parallel port
that can send and receive information.
BIOS - An Acronym for Basic Input/Output
System. Configures the system board and
provides hardware information to the operating
system.
Bit - A contraction of Binary digit. The smallest
unit of information in a binary number system. A
bit represents a choice between either zero or one.
Boot - To start up the computer and load the
operating system software. See cold boot and
warm boot.
Bus - A group of electronic paths used to send
data between parts of the system. On a system
board, the bus connects the peripheral cards with
the microprocessor via the expansion slots.
Bus Mastering - The ability of an peripheral card
to control the bus without requiring intervention
of the CPU.
Glossary
Byte - A group of adjacent bits treated as a unit.
Eight bits are typically considered one byte. Also
called a character.
Cache - A process where information is copied
from the slower memory (DRAM) to the faster
memory (SRAM). Information which is likely to
be read or edited is stored in the cache providing
significant performance increases.
Cache hit - The percentage of request for data
from memory that can be served from the cache.
Cache miss - A memory access which cannot be
supplied from cache.
Cold Boot - Starting the computer by turning on
the power or pressing the RESET button. A cold
boot makes the processor execute all of the
diagnostics. See boot and warm boot.
CPU - An acronym for Central Processing Unit.
A CPU performs arithmetic calculations, makes
logical decisions, and directs the operation of the
computer in conjunction with the operating
system.
Disk Drive - A hardware device which provides
for the storage of data on diskettes or hard metal
disks that have a magnetic coating. A disk drive
functions by spinning at high speed while moving
a device called the read/write head across the
disk’s surface in order to read or write data in
magnetic code.
DRAM - An acronym for Dynamic Random
Access Memory. A type of memory chip that
only keeps its memory if supplied with regular
clock pulses and a chance to regularly refresh its
data. It is slower and more cost effective than
SRAM. See SRAM.
ECP - An acronym for Extended Capabilities
Port. A standard set by Hewlett Packard and
Microsoft Corporation to expand the capabilities
of the parallel port.
EDO Memory - An acronym for Extended Data
Out. A type of DRAM with built-in cache.