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Glossary
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packet switching. Refers to protocols in which messages are divided
into packets before they are sent. Each packet is then transmitted individually
and can even follow different routes to its destination. Once all the
packets forming a message arrive at the destination, they are recompiled
into the original message
Most modern Wide Area Network
(WAN) protocols, including TCP/IP, X.25, and Frame Relay, are based on
packet-switching technologies. In contrast, normal telephone service is
based on a circuit-switching technology, in which a dedicated line is
allocated for transmission between two parties. Circuit-switching is ideal
when data must be transmitted quickly and must arrive in the same order
in which it's sent. This is the case with most real-time data, such as
live audio and video. Packet switching is more efficient and robust for
data that can withstand some delays in transmission, such as e-mail messages
and Web pages.
A new technology, ATM, attempts
to combine the best of both worlds -- the guaranteed delivery of circuit-switched
networks and the robustness and efficiency of packet-switching networks.
packets. A piece of a message transmitted over a packet-switching network. See under packet switching. One of the key features of a packet is that it contains the destination address in addition to the data. In IP networks, packets are often called datagrams.
page. A document, or collection of information, available through the World Wide Web. A page may contain text, graphics, video, and/or sound files. A page is the electronic unit of text that corresponds to a page in real life.
parallel port. A jack on the back of your computer that you can plug something into, especially a printer. The other kind of port is "serial." When a device is hooked up to the parallel port, it means that data is traveling at high speeds along parallel circuits in computer.
parameter. A parameter is simply a value passed to an object or to a function.
parity. Parity is a way of testing whether data is okay or not by counting the number of bits (such as during data transmission). The number can be either odd or even, and that information is saved and compared with subsequent calculations that also see if the number is odd or even.
park. To immobilize the heads of your hard drive so that they don't rattle around and do damage if the computer is moved.
password. A security measure used to restrict access to computer systems. A password is a unique string of characters that must be provided before a logon or an access is authorized.
path. The location of a file or directory. The path describes the location in relation to either the root directory, or the current directly.
path name. The route the computer takes to get to a specified file, spelled out in excruciating detail. The path includes the letter designating the drive, followed by a colon, followed by a backslash (\), followed by the directory, followed by any and all subdirectories, followed by the actual name of the file.
PC. Acronym for Personal Computer. Technically, refers to any stand-alone computer that fits on a desktop and is configured to address the computing needs of one user at a time.
PC card. The specification for credit-card sized adapter cards used primarily in laptop computers.
PDA. PDA (personal digital assistant) is a term for
any small mobile hand-held device that provides computing and information
storage and retrieval capabilities for personal or business use, often
for keeping schedule calendars and address book information handy. The
term handheld is a synonym. Many people use the name of one of the popular
PDA products as a generic term. These include Hewlett-Packard's Palmtop
and 3Com's PalmPilot.
Most PDAs have a small keyboard. Some PDAs have an electronically sensitive
pad on which handwritng can be received. Apple's Newton, which has been
withdrawn from the market, was the first widely-sold PDA that accepted
handwriting. Typical uses include schedule and address book storage and
retrieval and note-entering. However, many applications have been written
for PDAs. Increasingly, PDAs are combined with telephones and paging systems.
Some PDAs offer a variation of the Microsoft Windows operating system
called Windows CE. Other products have their own or another operating
system.
PDF. Acronym that stands for Portable Document Format, which is a type of file created by the Adobe Acrobat program. A PDF file contains text and graphics that can be viewed by anyone who uses an IBM or Macintosh computer, whether or not they actually have the Adobe Acrobat program on their hard disk. Unlike most files that can only be used on one specific type of computer, PDF files are meant to be shared among different types of of computers.
peer-to-peer. A democratic arrangement in networking technology where all nodes are created equal. A peer-to-peer relationship has no shared resources on a server. You can have a peer-to-peer relationship between computers in a network that contains servers. Each computer on the node acts as a server and a client.
peripheral. Any machinery connected to the computer, including monitors, printers, scanners, mice, external hard or floppy drives, CD-ROM drives, speakers, and keyboards.
Perl. Perl is a compiled scripting language written by Larry Wall. It is particularly useful for text processing and file conversion, Unix system administration and utilities, Web forms, and report generation.
Pine. Pine is a popular mail and Usenet client for Unix and Windows. Developed at the University of Washington, it offers an intuitive, easy-to-use menu interface and supports MIME, IMAP and PGP. Though it includes an extensive options list, in some cases, Pine sacrifices features for usability.
piracy. The copying, and/or distribution of software without the permission of the writer or publisher.
pixel. Short for PICture ELement, a dot that represents the smallest graphic unit of measurement on a screen. The actual size of a pixel is screen-dependent, and varies according to the size of the screen and the resolution being used. As atoms are to molecules, pixels are to pictures.
Plug-ins. Broadly speaking, plug-ins are software modules that add to the functionality of an application.
Point-to-point. A generic term for a dedicated connection between any two points on a network. Frequently used to refer to leased lines connecting two networks together.
polymorphic virus. A special virus that modifies itself each time it infects a file on your computer. By modifying itself, a polymorphic virus makes it harder for anti-virus programs to find and kill all possible strains of the virus.
POP. Acronym for Post Office Protocol. An Internet protocol for the retrieval of electronic mail from a mail server
POPmail. "POPmail" refers to e-mail software that is installed on your personal computer which sends and receives mail very quickly from a shared computer's electronic post office. The "POP" in POPmail stands for "post office protocol." Personal computers seldom have the network resources required to serve as an independent post office, which is why most people use shared systems or POPmail for e-mail. POPmail software on your personal computer (the "POP client") quickly logs into a shared computer which is an e-mail post office (a "POP server"), and transfers received mail from your account on that system to your workstation. When you send a message from your workstation, the POP client transfers it to a dedicated mail system for transmission on the Internet.
port. A jack in back of the computer where you can plug in a peripheral device. Ports are usually either serial or parallel.
PostScript. PostScript is a page description language (PDL) developed by Adobe Systems. In essence, it is a programming language for describing how a page is to be printed or displayed. (Examples of other PDLs include Envoy, PDF, and PCL.) PostScript consists of functions for describing and positioning lines, shapes, fills, and other graphical elements, and for placing and formatting text. Originally conceived as a means for communicating with printing devices, it has been adapted for screen displays (Display PostScript, as used by NeXT(tm) computers), and for embedding graphics in documents (Embedded PostScript, or EPS).
power surge. The amount of power flowing through your wires can vary considerably, and having it increase drastically and suddenly can cause damage to your computer's components. Most of this surge (or spike) is beyond your control, but, regardless of the cause, either computer user needs to install a device called a surge protector, between the computer and the wall. This offers full protection again power surges but offers no protection against other communicable diseases.
PPP. Acronym for Point to Point Protocol. The industry standard that is implemented in Dial-Up Networking. PPP is a line protocol used to connect to remote networking services, including Internet Service Providers (ISPs). Prior to the introduction of PPP, another line protocol, SLIP, was used.
PPPoE. Acronym for Point-to-Point Protocol over Ethernet.PPPoE relies on two widely accepted standards: PPP and Ethernet. PPPoE is a specification for connecting the users on an Ethernet to the Internet through a common broadband medium, such as a single DSL line, wireless device or cable modem. All the users over the Ethernet share a common connection, so the Ethernet principles supporting multiple users in a LAN combine with the principles of PPP, which apply to serial connections.
PRAM. The PRAM, or parameter RAM, in a Mac OS computer is a small amount of RAM which is not cleared when you turn off your computer's power. It is kept active by a small battery and stores such information as your monitor bit depth, Ethernet address, and mouse settings. Occasionally the PRAM can become corrupt and cause problems with your Mac OS computer. If you are experiencing certain problems, you can sometimes solve them by "zapping" the PRAM. This is done by holding down the Option, Command, P, and R keys while starting up or restarting your computer. This will automatically restart your computer a few seconds after it powers on. Keep holding the Command, Option, P, and R keys and allow your computer to restart 5 times. Then let it power up and boot normally. You may need to go in and change some of your settings, as they are reset to factory defaults.
Primary partition. Old DOS versions of the FDISK command allows you to create up to four partitions on your hard drive. One of the partitions can be designated a "Primary" partition, the others have to be "Extended." The Primary partition will be the one used to boot up the machine, and should be later formatted so that DOS or some other operating system resides on that partition. A partition must also be designated "Active," otherwise the BIOS (the on-chip program that starts when the computer is turned on) will ignore that partition, even if it is designated "Primary."
print driver. The software that acts as an interpreter between the operating system or application software and the particular make and model of printer you're trying to talk to.
print job. An order to print certain material in a certain way at a certain time. Everytime you hit the final OK key (or the equivalent) after making all your print specifications, that constitutes a print job.
print screen. An instruction to the computer to print the screen exactly the way it is.
print spooler. Software that manages a print queue and lets print jobs line up one after the other -- as if they were wrapped around a spool -- patiently feeding them to the printer in the background while the user is busy writing novels, crunching numbers.
printer port. The jack on the back of your computer that you plug your printer into -- usually a parallel port. (See also parallel port.)
programming language. A vocabulary and set of grammatical rules for instructing a computer to perform specific tasks. The term programming language usually refers to high-level languages, such as BASIC, C, C++, COBOL, FORTRAN, Ada, and Pascal. Each language as a unique set of keywords (words that it understands) and a pecial syntax for organizing program instructions.
property. In an object-oriented environment, an object's properties describe the characteristics of that object. For instance, an object's foreground color would be a property for a text object.
proprietary. Proprietary means the company that developed the design owns the design, and no one may duplicate it or distribute it without that company's permission.
protocol. A set of rules and conventions by which two computers pass messages across a network. Also, an agreed-upon format for transmitting data between two devices. The protocol determines the following:
public domain. Public domain software is released without any conditions upon its use. It may be copied, modified, and distributed as the user pleases. This type of software generally has the smallest level of support available.
pull-down menu. In a software application, a pull-down menu is a list of intriguing possibilities that appears when you select an option on the menu bar. To choose an item from the list, you drag the mouse down to it and let go, or use the appropriate keyboard strokes.
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