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Packet
Packet is a group of bits (including data and call control signals) transmitted as a whole on a packet-switching
network. Usually smaller than a transmission block.
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PAD (Packet Assembler-Disassembler)
PAD is an interface between a terminal or computer and a packet-switching network.
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Parity Check
Parity Check is the addition of noninformation bits to make up a transmission block that ensures the total number
of ones as always either even or odd; used to detect transmission errors.
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Parity Memory
Parity Memory uses a ninth bit for parity checking. The checking operation is performed by circuits on the motherboard,
not on the memory chips themselves. When a parity error occurs, most computers simply display a "parity error"
message, hang up and then must be rebooted.
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Parity Memory Checking
Parity Checking is an error detection technique that tests the integrity of digital data in memory or on disk.
Parity checking adds an extra parity cell to each byte of memory and an extra parity bit to each byte transmitted.
The value of the ninth bit (0 or 1) depends on the pattern of the byte's eight bits. Each time a byte is transferred
or transmitted, the parity bit is tested by memory controller circuits on the motherboard.
"Even" parity systems make the parity bit 1 when an even number of 1 bits are in the byte. "Odd"
parity makes it 1 when an odd number of 1 bits are present. Parity checking cannot detect the condition in which
two data bits are in error, because they would cancel themselves. The parity bit would still be correct for that
sequence of 0s and 1s. ECC is a much more robust memory checking system (see ECC memory).
There are 12% more memory cells in 9-bit parity chips than there are in 8-bit non-parity memory. To shave costs,
many computers are built with non-parity memory. It is truly a miracle that the data in the hundreds of millions
of non-parity computers in the world are maintained as perfectly as they are considering the trillions upon trillions
of bits moved daily. See RAID and ECC memory.
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Parse
Parse is to analyze or separate (input, for example) into more easily processed components. Used in software.
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Partition
Partition is a logical section of a disk. Each partition normally has its own file system.
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Partition Table
Partition Table is a 64-byte data structure that defines the way a PC's hard disk is divided into logical sectors
known as partitions. The partition table describes to the operating system how the hard disk is divided. Each partition
on a disk has a corresponding entry in the partition table. The partition table is always stored in the first physical
sector of a disk drive.
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Path
1. Path indicates the location of a file. The path consists of directory or folder names, beginning with the highest-level
directory or disk name and ending with the lowest-level directory name. A path can identify a drive (e.g. C:\),
a folder (e.g. C:\Temp) , or a file (e.g. C:\Windows\ftp.exe).
2. The portion of a URL that identifies the folders containing a file. For example, in the URL http://example.microsoft.com/hello/world/greetings.htm,
the path is /hello/world/.
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PCMCIA (Personal Computer Memory Card International Association)
PCMCIA is an expansion slot found in many laptop computers.
PCMCIA is an organization consisting of some 500 companies that has developed a standard for small, credit card-sized
devices, called PC Cards. Originally designed for adding memory to portable computers, the PCMCIA standard has
been expanded several times and is now suitable for many types of devices. There are in fact three types of PCMCIA
cards. All three have the same rectangular size (85.6 by 54 millimeters), but different widths.
PCMCIA CARDS
Type I cards can be up to 3.3 mm thick, and are used primarily for adding additional ROM or RAM to a computer.
Type II cards can be up to 5.5 mm thick. These cards are often used for modem and fax modem cards.
Type III cards can be up to 10.5 mm thick, which is sufficiently large for portable disk drives.
PCMCIA SLOTS
As with the cards, PCMCIA slots also come in three sizes:
A Type I slot can hold one Type I card
A Type II slot can hold one Type II card or one Type I card
A Type III slot can hold one Type III card or any combination of two Type I or II cards.
In general, PC Cards can be exchanged on the fly, without rebooting the computer. For example, slip in a fax modem
card when want to send a fax and then, when done, replace the fax modem card with a memory card.
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Peer-to-Peer Network
Peer-to-Peer Network is a network in which resources and files are shared without a centralized management source.
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Peripheral
Peripheral is any part of a computer other than the CPU or working memory (RAM and ROM). For example, disks, keyboards,
monitors, mice, printers, scanners, tape drives, microphones, speakers, and other such devices are peripherals.
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Physical Topology
Physical Topology is the physical layout of the network; how the cables are arranged; and how the computers are
connected.
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PING (Packet InterNet Groper)
PING is a utility used to determine which devices are available and responsive on a network or at an Internet site.
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Plug-and-Play
Plug-and-Play (PnP) is a hardware and software specification developed by Intel that allows a PnP system and a
PnP adapter to configure automatically . PnP cards generally have no switches or jumpers, but are configured via
the PnP system's BIOS or with supplied software for non-PnP computers.
PnP is an industry standard that allows computer peripherals to be automatically configured by an operating system.
Plug and Play eliminates the need for manually changing jumpers and other hardware settings when installing hardware,
and for restarting a computer after making a hardware change (for example, after inserting a PCMCIA card or plugging
a portable computer into a docking station). Plug-and-Play works best with a BIOS that can communicate up-to-date
configuration information, and an operating system that supports Plug-and-Play hardware by dynamically maintaining
system-wide configuration settings. Windows 9x has built-in Plug-and-Play support. It stores current configuration
information in the Registry, which gets updated whenever a configuration change occurs. Applications that support
Plug-and-Play are notified by Windows whenever there is a change in the system configuration.
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Plug-in
One of a set of software modules that integrate into Web browsers to offer a range of interactive and multimedia
capabilities.
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Point-to-Point
Point-to-Point is a direct link between two objects in a network.
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POP (Point of Presence)
POP is the place where a line from a long-distance carrier (IXC) connects to the line of the local telephone company
or to the user if the local company is not involved.
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Port
Port is a connection point for a cable. Port is one of the network input/output channels of a computer running
TCP/IP. On the World Wide Web, port usually refers to the port number a server is running on. A single computer
can have many Web servers running on it, but only one server can be running on each port. The default port for
Web servers is 80.
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POST (Power-On Self Test)
BIOS executes a series of tests collectively known as the POST each time a PC initializes. The test checks each
of the primary areas of the system, including the motherboard, video system, drive system, and keyboard, and ensures
that all components can be used safely. If a fault is detected, the POST reports it as an audible series of beeps
or a hexadecimal code written to an I/O port.
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POTS (Plain Old Telephone Service)
POTS is the basic analog service provided by the public telephone network, without any added facilities.
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PPP (Point-to-Point Protocol)
PPP is an Internet standard for transmitting data over serial links between computers.
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Presentation Layer
Presentation Layer uses the ASCII or EBCDEC data syntax. Makes the type of data transparent to the layers around
it. Used to translate date to computer specific format such as byte ordering. It may include compression. It prepares
the data, either for the network or the application depending on the direction it is going.
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Protocol
Protocol is the formal set of conventions governing the formatting and relative timing of message exchange between
two communicating systems. So, Protocol is a formal description of a set of rules and conventions that govern how
devices on a network exchange information. Protocl is a method of accessing a document or service over the Internet,
such as File Transfer Protocol (FTP) or Hypertext Transfer Protocol (HTTP). Also called type. Simply, the
"language" spoken between computers to help them exchange information. More technically, it's a formal
description of message formats and the rules that two computers must follow to exchange those messages. Protocols
can describe low-level details of machine-to-machine interfaces (like the order in which bits and bytes are sent
across a wire) or high-level exchanges between allocation programs (the way in which two programs transfer a file
across the Internet).
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Proxy server
An Internet server that acts as a firewall, mediating traffic between a protected network and the Internet. See
also firewall.
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PSTN (Public Switched Telephone Network)
PSTN is any switching communications system, such as Telex, TWX, or public telephone networks, that provides circuit
switching to many customers.
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Publish
To publish is to put your Web files up on a Web server so that others can access them.
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Push button
A form field that lets a user submit a form or reset a form to its initial state.
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