Specifications

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Appendix A Glossary
OLE (object linking and embedding) An
enhancement to the original Dynamic Data
Exchange (DDE) protocol that enables the user to
embed or link data created in one application to a
document created in another application and sub-
sequently edit that data directly from the final
document.
On-Board Diagnostics (OBD) A term that
refers to the self-diagnostic and reporting technol-
ogy and capability found in 1980s and newer auto-
mobiles with computer controlled engines.
online fallback A feature that enables high-
speed error-control modems to monitor line quality
and fall back to the next lower speed if line
quality degrades. Some modems fall forward as
line quality improves.
open architecture A system design in which
the specifications are made public to encourage
third-party vendors to develop add-on products.
The PC is a true open architecture system, but the
Macintosh is proprietary.
operating system (OS) A collection of pro-
grams for operating the computer. Operating sys-
tems perform housekeeping tasks, such as input
and output between the computer and peripherals
and accepting and interpreting information from
the keyboard. Windows XP and Vista are examples
of popular OSs used in PCs.
Opteron An AMD single-core and multi-core
processor built for workstation and server tasks.
Opteron supports AMD64 64-bit extensions. See
also AMD64.
Optical Character Recognition (OCR) A sys-
tem for optically scanning text from documents,
then translating the text into digital character data
that can be stored and searched via a computer.
optical disk A disk that encodes data as a series
of reflective pits that are read (and sometimes writ-
ten) by a laser beam.
Orange Book The standards for recordable
(CD-R) and rewritable (CD-RW) compact discs.
originate mode A state in which the modem
transmits at the predefined low frequency of the
communications channel and receives at the high
frequency. The transmit/receive frequencies are the
reverse of the called modem, which is in answer
mode. See also answer mode.
OS/2 An operating system originally developed
through a joint effort by IBM and Microsoft
Corporation and later by IBM alone. Originally
released in 1987, OS/2 is a 32-bit operating system
designed to run on computers using the Intel 386
or later microprocessors. The OS/2 Workplace Shell,
an integral part of the system, is a graphical inter-
face similar to Microsoft Windows and the Apple
Macintosh system. OS/2 Warp 4 is the most recent
version and is used primarily as a server or in back-
office functions today.
OSI (Open Systems Interconnection) A refer-
ence model developed by the International
Organization for Standardization (ISO) in the
1980s, the OSI model splits a computer’s network-
ing stack into seven discrete layers. Each layer pro-
vides specific services to the layers above and below
it. From the top down, the Application Layer is
responsible for program-to-program communica-
tion; the Presentation Layer manages data represen-
tation conversions. Next, the Session Layer is
responsible for establishing and maintaining com-
munications channels, and the Transport Layer is
responsible for the integrity of data transmission.
The Network Layer routes data from one node to
another, the Data Link Layer is responsible for
physically passing data from one node to another,
and finally, the Physical Layer is responsible for
moving data on and off the network media.
output Information processed by the computer
or the act of sending that information to a mass
storage device, such as a video display, printer, or
modem.
overclocking The process of running a proces-
sor or video card at a speed faster than the officially
marked speed by using a higher clock multiplier,
faster bus speed, or faster core clock speed. Not rec-
ommended or endorsed by processor or video card
manufacturers. See also clock multiplier.
OverDrive An Intel trademark name for its line
of upgrade processors for 486, Pentium, and
Pentium Pro systems. Although Intel no longer sells
OverDrive processors, similar products are available
from Evergreen Technologies and PowerLeap
Products, Inc., for these processors plus Pentium II,
Pentium III, Pentium 4, and Celeron-based systems.
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