P

PABX

See Private Automatic Branch Exchange.

PACKAGE

In a compound document, an embedded icon that contains an object, a file or part of a file, or a command.

PACKET

A unit of information sent over a network. A packet contains data and control and address information. A limited-length unit of data that is formed by the network, transport, presentation, or application layer (layers 3-7 of the OSI Model) in a networked computer system. Packet headers contain information that is used by each corresponding layer of protocol in a network architecture. Packets may or may not contain data, as their functions are often fulfilled by one of the codes in a field of the header or trailer. In all cases, data is transported over a network, and larger amounts of data are broken into shorter units and placed into packets. Higher-layer packets are encapsulated into lower-layer packets for encapsulation into LAN frames (or in WAN frames or packets) for delivery to the ultimate host destination. Packet is commonly used with microcomputer networks, and frame, with mainframe networks. The terms are sometimes considered synonymous, but the terms 'packet' and 'frame' should not be confused because each has different specific functions. Novell uses proprietary packet formats including IPX, SPX, NCP, RIP, and SAP packet formats based upon Xerox's XNS network architecture. (See: frame, network, network architecture, IPX, OSI Model, protocols, and UNA.)

PACKET ASSEMBLER / DISASSEMBLER

(PAD) A device used to interface non-X.25 devices to an X.25 network. It may be sync. or async, single or multiple channel. Equipment used to assemble and disassemble data packets for transmission on a packet-switching network such as a satellite system.

PACKET DRIVER

Small piece of software that sits between the network card and TCP program. Interrupt range in 0x60 to 0x7F.

PACKET INTERNET GROPER

(PING) A program used to test the accessibility of destinations by sending them an ICMP echo request and waiting for a reply. A client that searches for a remote user by IP address. Ping returns the remote user's log-in, as well as the local IP address information.

PACKET RADIO MODEM

An intelligent radio modem that packetizes the data it receives from the transmitting station. The modem places a header and a trailer around the data before it transmits the data to the destination device. The header can also contain routing information. Packet radio modems also perform their own data error checking and will re-transmit the data if an error is encountered.

PACKET RECEIVE BUFFERS

Packet receive buffers are areas in the file server memory set aside to temporarily hold data packets arriving from the various network stations. The file server holds these packets in buffers until the server is ready to process them and send them to their destination on the network.

PACKET SWITCH NODE

The modern term used for nodes in the ARPANET and MILNET. These used to be called IMPs (Interface Message Processors). PSNs are currently implemented with BBN C30 or C300 minicomputers.

PACKET SWITCHING

Sending data in packets through a network to some remote location. The data to be sent is subdivided into individual packets of data, each having a unique identification and each carrying its destination address. Each packet can go by a different route and may arrive in a different order than it was sent. The packet ID lets the data be reassembled in proper sequence. A data transfer scheme in which information is broken into individual packets, transferred across a communications link, and reassembled at the receiving end. In a packet-switching system, the route between the sender and receiver is determined by each node through which the packet travels.

PACT

Advanced two-way messaging and pagong technology designed to provide wireless messaging services. It operates in the 900Mhz range, using proven data protocols including TCP/IP and CDPD.

PAD

See Packet Assembler/Disassembler. See X.28, X.29, and X.3

PAGE FAULT

An interrupt that results when software requests a memory location that is being saved for auxiliary storage.

PAGE FRAME

A physical address in the upper memory area where a page of expanded memory can be mapped. The page frame itself can be a maximum of four 16K pages.

PAGING

A technique for implementing virtual memory, where the virtual address space is divided into fixed-sized blocks called pages, each of which can be mapped onto any physical addresses available on the system.

PAL

See Phase Alteration Line

PAL FORMAT

See Phase Alteration Line

PALETTE MANAGEMENT

A mechanism to choose which colors to display when the display device supports a limited number of colors for simultaneous display. For example, a VGA monitor can display 16 colors out of an overall palette of 256, so a DIB bitmap with more than 16 colors would have to be palettized.

PAP

Password Authentification Protocol

PAP

Printer Access Protocol

PAR

Positive Acknowledgement with Retransmission

PARITY

A data encoding scheme that computers (and terminals) use to check the validity of transmitted characters. This scheme adds an extra bit to each character, which the transmitting computer sets or clears based on the type of parity the computers agree to use (odd or even). For example, if the computers use even parity, the transmitting computer sets or clears the parity bit so that there are an even number of bits set in each character it transmits. The receiving computer checks each character and flags a parity error if any character has an odd number of bits set.

PARK

A feature (of the AT&T Merlin Legend system) that allows you to put a call on hold so that it can be answered from any phone in the system. You then page your co-worker and announce the call. Your co-worker can pick up the call from the nearest phone by using Pickup and dialing your extension.

PARTITION TABLE

See Master Boot Record.

PARTS PER MILLION DEFECTS PER JOINT

(ppm/j) A commonly used term to express the defect rate of solder joint connections.

PASSIVE HUB

See Hub.

PASSPHRASE

A secret string of characters known to a computer system and a particular user who must specify it to gain access to the system and its data. A passphrase allows imbedded spaces and mixed case characters to support more flexible and complex combinations than a password allows. LAN Distance security relies on a user ID to identify a user and can optionally require a passphrase to authenticate that user.

PASSWORD SHADOWING

A security system where the encrypted password field of /etc/passwd is replaced with a special token and the encrypted password is stored in a separate file which is not readable by normal system users.

PASTE

A function that copies the contents of the Clipboard and inserts it at the current cursor position.

PATH

In MS-DOS, the route the operating system follows to locate files on a disk or disks. On a network, the route between any two nodes.

PATH CONTROL LAYER

The third layer of the SNA model. The path control layer handles routing and traffic control. For example, it might group unrelated packets to send to the same address.

PATH CONTROL NETWORK

The part of an SNA network that links the network units and handles physical transmission. The path control network is similar to the physical and data link layers of the ISO OSI model.

PBGA

Plastic Ball Grid Array. See Ball Grid Array.

PBX

See Private Branch Exchange.

PBX DRIVER

The vendor dependent software specific to switch control. The PBX Driver is the service provider portion of the Telephony Server.

PBX DRIVER

The PBX driver handles CSTA or OA&M requests for a specific vendor's PBX. The PBX Driver may choose to provide OA&M services through the Telephony Server, or the Driver may choose to provide their own OA&M interface.

PC CARD

Credit-card size, 68-pin add-in cards that were designed to meet PCMCIA standards.

PC-NET

The IBM PC LAN program, an MS-DOS-based networking systems software product developed by Microsoft and IBM, which has been shipping since 1985.

PC/104

A standard which defines a compact, modular form-factor version of the PC bus on 3.6" x 3.8" cards. Used in embedded computer systems.

PCI

See Peripheral Component Interconnect bus. See Protocol Control Information.

PCM

See Pulse Code Modulation.

PCMAIL

Pcmail Transport Protocol

PCS

Personal Communications Services

PDA

Personal Digital Assistant

PDBS

pACT Data Base Station. See pACT.

PDIS

pACT Data Intermediate Systems. See pACT.

PDN

Public Data Network

PDU

See Protocol Data Unit.

PDX

Paradox

PE

Public Enemy

PEAK FACTOR

Ratio of peak value of any alternating current or voltage to the RMS value.

PEER PROCESS

In a network model, processes operating on the same levels of different computers; for example, on layer 7 of computer A and layer 7 of computer B.

PEER-TO-PEER NETWORK

A network whose nodes can each act with equal authority, without having a master-slave relationship.

PEP

Packet Exchange Protocol

PERIMETER ARRAY

A BGA that has its center bumps depopulated such that only its outer rings are available for connection.

PERIPHERAL COMPONENT INTERCONNECT

(PCI) A local bus developed by Intel. 32 bits wide, delivering a peak bandwidth of 133 Mbyes per second at 33MHz . With typical overhead, the actual data throughput is measuerd at 80 Mbytes per second. Supports ISA, EISA, and MCA. It is processor independent. Linear Bursts keep the bus filled with data so more bandwidth is used for data, not addresses. Low-Access Latency gives peripherals faster control of the bus. Bussmastering lets intelligent peripherals take control of the bus to speed high-priority tasks. Many abilities have been added, such as 64-bit multiplexed data and address bus, plug-and-play capability, etc. 64-bit data-bus transfers have a theoretical throughput of 532 Mbytes per second at 66mhz. PCI bus transmits data by making use of reflected waves produced in an unterminated transmission line. It control signals so that their reflection is amplified at the appropriate termination point on the bus. This reduces power requirements and inrcreases transmission speed.

PERMALANCER

A permanent freelancer. A person hired on a per-project basis who lives a benefits-free existance.

PERMANENT VIRTUAL CIRCUIT

A Frame Relay and X.25 feature in which data traveling between to end points uses a pre-established path. See Frame Relay.

PERSONAL ACCOUNT

An entry in the User Account database that contains security specifications for a particular user. A Personal Account is the subset of fields that the specific user can alter, the passphrase and user description. The complete set is managed by the LAN Distance security administrator.

PES

pACT End System. See pACT.

PFOVR

Percent Field-of-View Resolved. Usually relating to tolerance.

PHASE ALTERATION LINE

(PAL) Video format used in most of Western Europe, Australia and other countries. 625 lines of resolution at 25 frames per second.

PHASE ROTATION

The normal phase sequence of the power system being monitored.

PHOENIX

BIOS manufacturer for PCs.

PHY

See Physical Layer Protocol.

PHYSICAL ADDRESS

The unique address associated with each workstation on a network.

PHYSICAL COMMUNICATION

The actual transmission of data from one computer to another; this occurs on the physical layer of the OSI or SNA model.

PHYSICAL HOP

A hop as counted when crossing a bridge or a router. Each physical hop incurs latency as a result of delay in processing a frame for bridging or a packet for routing.

PHYSICAL LAYER

The OSI layer that provides the means to activate and use physical connections for bit transmission. In plain terms, the Physical Layer provides the procedures for transferring a single bit across a Physical Media. The hardware connection (for example, cabling) between two computers used for transmitting data.

PHYSICAL LAYER PROTOCOL

A protocol function that links one FDDI station to another and provides the bit clocks for each station and an elasticity buffer between the receiver and transmitter. PHY also transmits 7 line states.

PHYSICAL MEDIA

Any means in the physical world for transferring signals between OSI systems. Considered to be outside the OSI Model, and therefore sometimes referred to as "Layer 0." The physical connector to the media can be considered as defining the bottom interface of the Physical Layer, i.e., the bottom of the OSI Reference Model.

PHYSICAL MEDIA DEPENDENT

A function of the FDDI interface card that provides the power levels and characteristics of the optical transmitter and receiver, optical signal requirements, and bit error rates.

PHYSICAL UNIT

(PU) An SNA software component that manages a physical device and represents it to the network. Each PU supports one or more logical units (LUs). The closest microcomputer term is node, although it does not distinguish between physical and logical types.

PICMG

PCI Industrial Computers Manufacturer's Group

PICTURE ELEMENT

(Pixel) The minimum raster display element, represented as a point with a specified color or intensity level. One way to measure picture resolution is by the number of pixels used to create the image.

PIF

See Program Information File.

PIN

Personal Identification Number

PING

See Packet Internet Groper.

PIPE

1. A portion of memory used to pass data from one process to another, symbolized in MS-DOS by the | character. For example dir | sort sends the output of the directory listing to the sort command. 2. In a sample statement for a Windows initialization file or in an MS-DOS command, the symbol used to show that only one of the possible values can be used in the statement.

PITCH

Denotes the horizontal size of a fixed-width font in characters per inch.

PIV

Peak Inverse Voltage, rating applied to diodes.

PIXEL

See Picture Element.

PKE

Passive Keyless Entry

PLAIN OLD TELEPHONE SERVICE

See Plain Old Telephone System.

PLAIN OLD TELEPHONE SYSTEM

The basic telephone service: standard single line telephones, telephone lines, and access to the public switched network. There are no added features, such as call waiting or call forwarding, with POTS.

PLC

Programmable Logic Controller

PLD

Programmable Logic Device (Logic simulation acronym)

PLENUM CABLE

Most urban fire and building codes require the use of Teflon-jacketed plenum cable anywhere cable is installed in the air handling system, such as in a suspended ceiling. This requirement is due to plenum's fire-resistant properties and low smoke producing qualities if it is burned. When non-plenum cable, usually polyvinyl-chloride (PVC), is used, it must be installed in conduit as mandated by local building codes. Since LANs tend to be dynamic in nature, money spent on plenum cable is a good investment, since plenum cable will afford the most flexibility for cable runs, even after the initial installation. In addition, plenum cable generally has better signal propagation properties than non-plenum cable.

PLI

Programmable Logic Interface (Logic simulation acronym)

PLV

See Production Level Video.

PMD

See Physical Media Dependent.

POINT SIZE

The vertical size of a font. A point is 1/72 inch.

POINT TO POINT PROTOCOL

(PPP) PPP is part of a new generation of synchronous protocol designed to be used with great flexibility. PPP has been developed by several vendors who are working together to define a standard so that their products will work with one another. Novell and other vendors use PPP in several of their communications products. PPP shows great promise if vendors are able to develop a standard that will enable interoperability. Novell and other vendors have formed a consortium to unite emerging variations of PPP development projects for future compatibility. PPP is not restricted by speed and can operate at very high rates through modern digital switches. Therefore, it should not become obsolete as new types of media become available. Evolved to address the shortcomings of SLIP. PPP uses a negotiation scheme to advertise what portion of the 'feature set' it provides. Thus, one vendor may implement a full set of features with its PPP, while another may chose to provide only a subset. Each end of a communication link will then agree on a common set of features to be used. Note that this negotiation occurs automatically. PPP is made up of three main components: an encapsulation scheme, a Link Control Protocol, and a group of of Network Computing Protocols for functionality within different network layer protocols. PPP is able to determine automatically which network protocols are supported through NCP negotiations. To establish a link between two points, PPP sends a Link Control Packet to test and configure the link. After the link is established, an authentication scheme can be applied. When the configuration is complete, data can then be transfered. The important thing to note is that PPP can use different encapsulation and varying frame sizes, thus providing flexibility to operate in heterogeneous networks.

POINT-OF-PRESENCE

(POP) A long distance carrier's office in your local community. A POP is the place where your long distance carrier, or IXC, terminates your long distance lines just before those lines are connected to your local phone company's lines or to your own direct hookup. Each IXC can have multiple POPs within one LATA. All long distance phone connections go through the POPs.

POLAR TRANSMISSION

See Bipolar Transmission.

POLL

When the master station sends a message to a remote station that allows the remote station an opportunity to return a response to the master or another remote station.

POLL LIST

A list of nodes or stations on a network to be polled on a regular and repeated basis.

POLLING CYCLE

The order and frequency in which network nodes in a poll list are polled.

POLYMORPHIC VIRUS

A virus that attempts to evade detection by changing its internal structure or its encryption techniques.

POOL BUTTON

A line button you use to make and receive outside calls on phones with SA buttons. Part of the AT&T Merlin Legend system.

POOLING

A method of assigning codes that control host session allocation on LAN workstations. Host sessions can be pooled in one of the three following ways: 1. All workstations use the same access code. 2. All workstations use a unique access code. 3. Some workstations use the same access code.

POP

See Point-Of-Presence. OR Post Office Protocol

POP2

Post Office Protocol Version 2

POP3

Post Office Protocol Version 3

POPS

Plain Ol d Paging Service

PORT

The abstraction used by Internet transport protocols to distinguish among multiple, simultaneous connections to a single destination host. See selector. OR See communication port.

PORTABLE OPERATING SYSTEM INTERFACE - UNIX

(POSIX) A set of software standards being developed by the IEEE POSIX Working Group, to allow applications to be written to a single target environment in which they can run unchanged on a variety of systems. The POSIX speci fications define characteristics for operating systems, DBMS, data interchange, network ser vices, user interface, and programming interfaces. Several vendors plan to make their operating systems POSIX-compliant.

POSI

See Promoting Conference for OSI.

POSIX

See Portable Operating System Interface - UNIX

POST

Power On Self Test

POSTING

The act of sending an articlearticle to the Usenet network, to be seen by potentially hundreds of thousands of individuals. Also, a synonym for "article".

POTS

See Plain Old Telephone System.

PPM/J

See Parts Per Million Defects Per Joint.

PPP

See Piont-to-Point Protocol.

PRECISE DIAL TONE

A North American standard tone consisting of 350Hz plus 440Hz. See Dial Tone.

PREEMPTIVE PROCESSING

In a multitasking operating system, multiple tasks (threads) are generally controlled by a scheduler that preempts or interrupts each process, granting processor time in the form of a time slice (about 1/18th of a second). This enables multiple tasks to apparently run at the same time. However, each task runs for a time slice and is then preempted by the next process, which in turn is preempted-rotating processor time among active threads. In most Intel-based, multitasking operating systems, the scheduler executes in ring 0, and threads are executed in ring 3. See Processor Ring, Thread, and Time Slice)

PRESENTATION ADDRESS

See OSI Presentation Address.

PRESENTATION DATA

Information needed to render the object on a display device

PRESENTATION LAYER

The sixth layer of the ISO OSI model. It performs layer frequently used routines, such as translating data between EBCDIC and ASCII. The OSI layer that determines how Application information is represented (i.e., encoded) while in transit between two end systems.

PRESENTATION TRACE

A diagnostic trace used in the gateway to check the data flow between the gateway and the workstation.

PRI

See Primary Rate Interface and ISDN.

PRIMARY RATE INTERFACE

(PRI) The Primary Rate Interface (that which is delivered to the customer's premises) provides 23B+D or 30B+D running at 1.544 megabits per second and 2.048 megabits per second, respectively.

PRIMARY STATION

In an SNA network, the station that controls the link and determines when other stations may transmit. Compare secondary station.

PRIMARY TARGET

The operating system that is best suited to run an integrated solution.

PRIMITIVES

In computer programming, it refers to the basic, elemental parts of the computer programming language.

PRINT SERVER

A network node, usually consisting of fixed-disk storage and a CPU, that controls one or more printers that can be shared by users.

PRINTABLE SCREEN FONTS

Windows screen fonts that can be translated for output on the printer.

PRIVATE AUTOMATIC BRANCH EXCHANGE

(PABX) Means of switching telephone calls within a business site and from the site to outside lines. Can also be used for low speed data.

PRIVATE BRANCH EXCHANGE

A PBX is a private telephone switch. It is connected to groups of lines from one or more central offices and to all of the telephones at the location served by the PBX.

PRIVATE MANAGEMENT DOMAIN

An X.400 Message Handling System private organization mail system. Example: NASAmail. See ADMD.

PRIVATELENGTH

(For a Telephony Services Driver Interface) The privateLength is a value that provides the length of the private data associated with this Driver Control block. This field must be set to 0 if no private data is associated with this Driver Control block.

PRIVATEOFFSET

(For a Telephony Services Driver Interface) The privateOffset is a values that determines the start of the private data associated with this Driver Control block. The privateOffset must be added to the address of the Driver Control block to get to the beginning of the private data. This field should be set to 0 if no private data is included with the Driver Control block.

PRIVILEGE

A security designation that entitles a user to perform a set of tasks. Privileges are based on the user-type definitions of user, LAN Distance administrator, and LAN Distance security administrator, and are assigned within a user account.

PRM

Packet Radio Measurement

PRMD

See Private Management Domain.

PROCESSOR

The controlling device in a computer that interprets and executes instructions and performs computations, and otherwise controls the major functions of a computer. For example, Intel 80x86-series processors, which are miniaturized single-chip 'microprocessors' that contain thousands to millions of transistors in a silicon-based, multilayered integrated circuit design.

PROCESSOR OVERHEAD

The part of the operating cycle used for housekeeping and setup purposes.

PROCESSOR RING

Intel 80286 and higher processors execute threads in one of four rings. Ring 0 is termed the 'most favored' ring, having priority over threads running in rings 1, 2, and 3. Each lower-numbered ring has priority over higher-numbered rings. NetWare executes its scheduler and all threads in ring 0 to affect nonpreemptive processing. Most multitasking operating systems execute code in ring 3, whereas a scheduler executes in ring 0, which has the capability to preempt the thread. Ring 3 has memory protection so that memory being utilized by each thread is protected from potential corruption from other threads that are concurrently running. See Preemptive Processing and Nonpreemptive Processing.

PROCESSOR UTILIZATION

The percentage of clock cycles that the processor is busy. When processor utilization reaches 100 percent, the processor cannot process more requests; it is fully saturated.

PRODUCTION LEVEL VIDEO

An asymmetric compression algorithm that runs on I750® processors. Source video is sent to a Digital Compression Facility (DCF), where a supercomputer processes it frame-by-frame to provide superior image color and quality. PLV was designed by Intel and is available with the ActionMedia®II board.

PROGRAM

Software that performs a defined function on a computer. See Executable.

PROGRAM GROUP

A set of several programs whose icons can be acted on as a single entity in Windows Program Manager. For example, if icons are associated with a single group icon, clicking the program group icon causes the icons for each of the programs in the group to be displayed.

PROGRAM INFORMATION FILE

Contains information about a non-Windows application, such as how much memory it needs. Windows uses this information to run the application in the most efficient way.

PROGRAMMERS

People who write boring business finance programs for corporations. They are smart and have lots of money. They hate their jobs. See Software Writers.

PROGRESSIVE SCANNING

Method of scanning image information out of CCD in a sequential, line-by-line basis.

PROMOTING CONFERENCE FOR OSI

The OSI "800-pound gorilla" in Japan. Consists of executives from the six major Japanese computer manufacturers and Nippon Telephone and Telegraph. They set policies and commit resources to promote OSI.

PROTECTED MEMORY

Memory areas into which you are unable to write.

PROTECTED MODE

An operating mode for the Intel 80286 and higher processors that supports multitasking, data security, and virtual memory.

PROTOCOL

A set of rules that governs how data is transmitted. To communicate successfully, two computers must use the same protocol. In networks, several layers of protocols exist. Each layer of protocol only needs to physically hand off or receive data from the immediate layer above and beneath it, whereas virtual communications occur with the corresponding layer on another host computer. Layers between the two hosts are transparent. See OSI Model, UNA, and Access Protocol.

PROTOCOL CONTROL INFORMATION

(PCI) The protocol information added by an OSI entity to the service data unit passed down from the layer above, all together forming a Protocol Data Unit (PDU).

PROTOCOL DATA UNIT

An OSI packet exchanged between ESs that contains protocol control information and user data. A data object exchanged between the Telephony Server and the client application.

PROTOCOL ELEMENT

A protocol-level command for performing FTP operations on the protocol level. After you have established an FTP session, you can enter REMOTEHELP from the FTP prompt. FTP then displays a list of FTP protocol elements recognized by the FTP server (for example, USER, PORT, XEXC). Most FTP servers support a subset of available protocol elements. Elements that begin with the letter X are experimental. Refer to RFC 959 for additional information about FTP protocol elements.

PROTOCOL STACK

The software modules that take data from an application and transform or encapsulate it for transmission across a network. The stack may have several layers of modules. Each layer provides services to the layer above; each layer requests services from the layer below. Examples of protocol stacks are IPX, TCP/IP, and OSI. The protocol stack receives packets of information from the LSL and is unaware of the media or LAN board type through which it passed. It then removes the protocol specific header information and passes the packets on to other higher-layer protocols or applications. The most popular types of protocol stacks are IPX/SPX, TCP/IP, AppleTalk, and OSI.

PROVIDER INTERFACE

A Microsoft Windows API for the provision of centralized administrative support of the client workstation over the network. Providers of network services will use this API, which will be fully open to the development community.

PROXY

The mechanism whereby one system "fronts for" another system in responding to protocol requests. Proxy systems are used in network management to avoid having to implement full protocol stacks in simple devices, such as modems.

PROXY ARP

The technique in which one machine, usually a router, answers ARP requests intended for another machine. By "faking" its identity, the router accepts responsibility for routing packets to the "real" destination. Proxy ARP allows a site to use a single IP address with two physical networks. Subnetting would normally be a better solution.

PSN

See Packet Switch Node.

PSP

Presentation Services Process

PSPDN

Packet Switched Public Data Network

PSTN

See Public Switched Telephone Network.

PSY

Psychose

PT

Thermostat cable with solid conductor, individual insulation, twisted together.

PTP

Point-to-Point

PU

See Physical Unit.

PUBLIC DOMAIN

(Specific legal meaning) It means that the creator of a work (in this case, software), who had legal ownership of that work, has given up ownership and dedicated the work "to the public domain". Once something is in the public domain, anyone can use it in any way they choose, and the author has no control over the use and cannot demand payment for it. Programs are often described by authors as being "public domain" when, in fact, they are shareware or free, copyrighted software. To be sure a program is public domain, you should look for an explicit statement from the author to that effect.

PUBLIC SWITCHED TELEPHONE NETWORK

(PSTN) Any switching system that provides a circuit switched to many customers. Four types exist in the USA. Telex, TWS, telephone, and Broadband Exchange.

PUC

Public Utility Commission

PULL

Used parts, removed from equipment, usually Ics or similar components from PC boards.

PULSE CODE MODULATION

The most common method of encoding an analog signal into a digital bit stream. A digitization technique, not a universally accepted standard.

PULSE DIALING

A method of dialing the telephone where the modem sends pulses (which you hear through the handset as clicks) to represent the telephone numbers (one pulse for a one, two pulses for a two, etc.). Pulse dialing is normally associated with rotary-dial phones. See also Tone Dialing.

PUP

PUP Protocol

PVC

See Permanent Virtual Circuit.

PWDGEN

Password Generator Protocol

PX64

Similar to MPEG, but adapted to slower bit rate. Typically used for video conferencing over an ISDN phone line.

PYRAMID INTEGRATOR

Allen-Bradley plant floor architecture that integrates a broad range of programmable logic controllers, control modules, and the MicroVAX Information Processor module in a single chassis. Communication among the modules occurs on the Pyramid Integrator backplane.