NEC PowerMate CT, Инструкция по обслуживанию и справочник

Страница: 159 / 167

14 Glossary
system board
The main printed circuit board inside the system unit into which other boards and major
chip components, such as the system microprocessor, are connected.
T
tpi
Tracks per inch.
track
Any of many concentric circular regions on a disk for storing data. Tracks are divided into
sectors. One measure of storage density of a disk is tpi.
U
Ultra DMA
A protocol developed by Quantum Corporation and Intel that supports burst mode data
transfer rates of 33.3 MBps. This is twice as fast as the previous disk drive standard for PCs,
and is necessary to take advantage of new, faster Ultra ATA disk drives. The official name
for the protocol is Ultra DMA/33.
USB
Universal Serial Bus. An external bus standard that supports data transfer rates of 12 Mbps
(12 million bits per second). A single USB port can be used to connect up to 127 peripheral
devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play
installation and hot plugging. It is expected to eventually replace serial and parallel ports.
V
VESA
Video Electronics Standards Association. The source of a SuperVGA standard used on
many video boards.
virus
Software that copies itself onto hard drives and diskettes without user intervention, usually
when a diskette is placed into the drive of a computer. Viruses usually trigger a harmless or
destructive occurrence on the system, activated by some preset condition. Viruses are
frequently written with antisocial intent.
VGA
Video Graphics Array. Graphics technology that supports up to 256 K colors and a graphics
resolution of 640 by 480 pixels.
volatile memory
Storage media that loses its data when system power is turned off. Standard memory and
memory added to the system are volatile memory. See nonvolatile memory.