Operating instructions

HRR (horizontal refresh rate) The amount of time it takes for a CRT to draw
one horizontal line of pixels on a display.
HTML (Hypertext Markup Language) An ASCII-based, script-like language
for creating hypertext documents like those on the World Wide Web.
HTTP (Hypertext Transfer Protocol) Extremely fast protocol used for network
file transfers in the WWW environment.
HTTPS (HTTP over Secure Sockets Layer) A secure form of HTTP, used com
-
monly for Internet business transactions or any time when a secure connection is
required. See also HTTP.
hub An electronic device that sits at the center of a star topology network,
providing a common point for the connection of network devices. Hubs repeat
all information out to all ports and have been replaced by switches, although the
term is still commonly used.
HVD (high-voltage differential) A rare type of SCSI device that uses two wires
for each bit of information: one wire for data and one for the inverse of this data.
The inverse signal takes the place of the ground wire in the single-ended cable.
By taking the difference of the two signals, the device can reject the com-
mon-mode noise in the data stream.
hyperthreading A CPU feature that enables a single pipeline to run more
than one thread at once.
I/O (input/output) A general term for reading and writing data to a computer.
The term “input” includes data from a keyboard, pointing device (such as a
mouse), or loading a file from a disk. “Output” includes writing information to
a disk, viewing it on a CRT, or printing it to a printer.
I/O addressing The process of using the address bus to talk to system devices.
ICF (Internet Connection Firewall) A software firewall built into Windows
XP that protects your system from unauthorized access from the Internet.
ICH (I/O controller hub) The official name for the Southbridge chip found in
Intel’s chipsets.
icon A small image or graphic, most commonly found on a system’s desktop,
that launches a program when selected.
34 MIKE MEYERS’ A+ CERTIFICATION PASSPORT
Passport / Mike Meyers‘ A+ Certification Passport / Meyers / 226308-3 / Glossary
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