Specifications

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Appendix A Glossary
24x7 Refers to continuous 24 hours a day, 7 days
a week computer or services operation.
56K The generic term for modems that can
receive data at a maximum rate of 56Kbps. See also
V.90, V.92, X2, K56flex.
64-bit processor A processor that has 64-bit reg-
isters. The Intel Itanium and Itanium 2 processors
for workstations and servers, which can also emu-
late 32-bit Intel processors; the AMD Athlon 64
desktop processor, which also emulates 32-bit x86
Intel and AMD processors; and the AMD Opteron,
designed for use in server and workstation tasks, are
some of the 64-bit processors now available.
100BASE-T A 100Mbps CSMA/CD Ethernet local
area network (LAN) that works on Category 5
twisted-pair wiring. 100BASE-T Ethernet LANs work
on a “star” configuration in which the wire from
each workstation routes directly to a central
100BASE-T hub. This is the current standard for
100Mbps Ethernet, replacing 100BASE-VG.
100BASE-VG The joint Hewlett-Packard–AT&T
proposal for Fast Ethernet running at 100Mbps. It
uses four pairs of Category 5 cable using the
10BASE-T twisted-pair wiring scheme to transmit or
receive. 100BASE-VG splits the signal across the
four wire pairs at 25MHz each. This standard has
not found favor with corporations and has been
almost totally replaced by 100BASE-T.
286 See 80286.
386 See 80386DX.
404 Website error code indicating the specified
page is not found. Some websites display a cus-
tomized error message instead of the standard 404
code.
486 See 80486DX.
586 A generic term used to refer to fifth-
generation processors similar to the Intel Pentium,
such as the AMD K6 series and the VIA Cyrix MII.
640KB barrier The limit imposed by the PC-
compatible memory model using DOS mode. DOS
programs can address only 1MB total memory, and
PC compatibility generally requires the top 384KB
to be reserved for the system, leaving only the lower
640KB for DOS or other real-mode applications.
802.11 The family name for various wireless
Ethernet standards. See also IEEE 802.11 family.
1000BASE-T A 1,000Mbps Ethernet local area
network (LAN) that runs over four pairs of Category
5 cable. Popularly known as Gigabit Ethernet,
1000BASE-T can be used as an upgrade to a prop-
erly wired 100BASE-T network because the same
cable and distance limitations (100 meters) apply.
1394 See FireWire.
8086 An Intel microprocessor with 16-bit regis-
ters, a 16-bit data bus, and a 20-bit address bus.
This processor can operate only in real mode.
8087 An Intel math coprocessor designed to per-
form floating-point math with much greater speed
and precision than the main CPU. The 8087 can be
installed in most 8086- and 8088-based systems
and adds more than 50 new instructions to those
available in the primary CPU alone.
8088 An Intel microprocessor with 16-bit regis-
ters, an 8-bit data bus, and a 20-bit address bus.
This processor can operate only in real mode and
was designed as a low-cost version of the 8086.
8514/A An analog video display adapter from
IBM for the PS/2 line of personal computers.
Compared to previous display adapters, such as
EGA and VGA, it provides a high resolution of
1,024×768 pixels with as many as 256 colors or 64
shades of gray. It provides a video coprocessor that
performs two-dimensional graphics functions inter-
nally, thus relieving the CPU of graphics tasks. It
uses an interlaced monitor and scans every other
line every time the screen is refreshed.
80286 An Intel microprocessor with 16-bit regis-
ters, a 16-bit data bus, and a 24-bit address bus. It
can operate in both real and protected virtual
modes.
80287 An Intel math coprocessor designed to
perform floating-point math with much greater
speed and precision than the main CPU. The 80287
can be installed in most 286- and some 386DX-
based systems, and it adds more than 50 new
instructions to what is available in the primary
CPU alone.
80386 See 80386DX.
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