Specifications
Glossary
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a palette of 64) colors. The EGA outputs a TTL (dig-
ital) signal with a horizontal scanning frequency of
15.75KHz, 18.432KHz, or 21.85KHz, and it supports
TTL color or TTL monochrome displays.
EIA (Electronic Industries Association) An
organization that defines electronic standards in
the United States.
EIDE (Enhanced Integrated Drive
Electronics) A specific Western Digital imple-
mentation of the ATA-2 specification. See also
ATA-2.
eight-way server A server containing eight
processors.
EISA (Extended Industry Standard
Architecture) An extension of the Industry
Standard Architecture (ISA) bus developed by IBM
for the AT. The EISA design was led by Compaq
Corporation. Later, eight other manufacturers (AST,
Epson, Hewlett-Packard, NEC, Olivetti, Tandy,
Wyse, and Zenith) joined Compaq in a consortium
founded September 13, 1988. This group became
known as the “gang of nine.” The EISA design was
patterned largely after IBM’s Micro Channel
Architecture (MCA) in the PS/2 systems, but unlike
MCA, EISA enables backward compatibility with
older plug-in adapters. EISA products became obso-
lete after the development of the PCI slot architec-
ture. See also PCI.
electromagnetic pulse (EMP) An intense
pulse of electromagnetic radiation, often from a
nuclear explosion.
electronic mail (email) A method of transfer-
ring messages from one computer to another.
electrostatic discharge (ESD) The grounding
of static electricity. A sudden flow of electricity
between two objects at different electrical poten-
tials. ESD is a primary cause of integrated circuit
damage or failure.
ELF (extremely low frequency) A very low-
frequency electromagnetic radiation generated by
common electrical appliances, including computer
monitors. The Swedish MPR II standard governs
this and other emissions. Also called VLF (very
low frequency).
EM64T Intel’s implementation of the AMD64
64-bit processor architecture. See also AMD64.
embedded controller In disk drives, this is a
controller built into the same physical unit that
houses the drive rather than on a separate adapter
card. IDE and SCSI drives both use embedded con-
trollers.
embedded servo data Magnetic markings
embedded between or inside tracks on disk drives
that use voice-coil actuators. These markings enable
the actuator to fine-tune the position of the
read/write heads.
EMM (expanded memory manager) A driver
that provides a software interface to expanded
memory. EMMs were originally created for
expanded memory boards but also can use the
memory management capabilities of the 386 or
later processors to emulate an expanded memory
board.
EMM386.EXE is an example of an EMM that
comes with DOS and Windows 9x.
EMS (Expanded Memory Specification)
Sometimes also called the LIM spec because it was
developed by Lotus, Intel, and Microsoft. Provides a
way for microcomputers running under DOS to
access additional memory. EMS memory manage-
ment provides access to a maximum of 32MB of
expanded memory through a small (usually 64KB)
window in conventional memory. EMS is a cumber-
some access scheme designed primarily for pre-286
systems that could not access extended memory.
emulator A piece of test apparatus that emulates
or imitates the function of a particular chip.
encoding The protocol by which data is carried
or stored by a medium.
encryption The translation of data into unread-
able codes to maintain security.
End User License Agreement (EULA) A type
of license or legal contract used for most software,
the application of which often depends on simply
opening the package.
endec (encoder/decoder) A device that takes
data and clock signals and combines (or encodes)
them using a particular encoding scheme into a
single signal for transmission or storage. The same
device also later separates (or decodes) the data and
clock signals during a receive or read operation.
Sometimes called a data separator.
Appendix A
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