PAN:  Personal Area Network.  See Bluetooth for more.

PANTONE:  Refers to a the most widely used color system of over 1200 standard colors developed by Pantone, Inc. in 1963 by Lawrence Herbert, Pantone’s founder.  Each color is specified by a number, and colors can be further broken down into a color calibration used by professional printers to calibrate color reproduction.  By permitting the specification of a color by number, you are assured getting the correct color when the file is printed, even though it may not look correct when shown on your monitor or printed on every printer.  Pantone Matching System (“PMS”) is used for “spot” colors (e.g., the background orange for this web page is identified as #FF6600); generally “process” colors are specified using the CMYK color model.  Spot refers to printing each color with its own ink; in contrast, process color printing uses four inks (Cyan, Magenta, Yellow & Black - CMYK) to produce all colors.  Spot color printing is effective only when the printed matter contains less than  three different colors, but becomes prohibitively expensive for more.

PARADIGM:  While this word has connotations outside of computers and engineering, at least since the 1960s the term refers to a “thought pattern” in a specific discipline, e.g. computer science. It is the set of practices that define a scientific disclipline at any given period of time.  A major change in scientific thinking is often called a “paradigm shift.”

PARENT:  The directory one up from the one you are in, until you reach the topmost root directory for that drive.  See also child, root.

PERSONAL AREA NETWORK (“PAN”):  A computer network (also sometimes called a “piconet” of up to 8 active (and many more inactive) devices in a master-slave relationship (the first device being the master), used for communication among computer devices, including telephones, earbuds, radios, PDAs, Blackberrys, laptops, etc.  within a range of about 8 to 10 meters.  PANs can be used for communication between the devices themselves (intrapersonally) or for an uplink to the Internet.  A Wireless Personal Area Network is called a “WPAN”. Uses Bluetooth and other protocols.

PARALLEL:  A type of port and cables for those ports invented in the 1970s (See, Centronics), adapted for the IBM PC in 1981 and standardized by the IEEE in 1984.  It was primarily used for printers, but has been almost completely replaced by USB serial ports which are considerably faster.  Parallel ports are now hardly ever included on system boards.

PARALLEL COMPUTING:  Solving a problem using multiple computers simultaneously.  This term covers a wide variety of possible architectures, including symmetric multiprocessing (“SMP”), clusters of SMP systems, massively parallel processors (“MPPs”), grid computing, distributed computing, cluster computing and hypercubing (binary multiples of computers, i.e. 4, 8, 16, etc.).  One example of this type of computing would be the model used by SETI (“Search for ExtraTerrestrial Intelligence), which is a huge grid computing project on the Internet that takes advantage of unused processing time in users’ computers to analyze radio telescope data.

PARETO PRINCIPLE:  Sometimes simply known as the 80-20 Rule, was named after Vilfredo Pareto, an Italian economist, who observed that 20% of Italy’s population received 80% of its income.  He went on to test this theory in numerous social sciences and engineering and found it to hold true.  Symantec claims that the principle is applicable for phishing and virus attacks as well.

PARC:  Short for Xerox’s Palo Alto Research Center, a major contributor to many computer hardware and software innovations. See Xerox for more.

PARITY:  A method of checking for the accuracy of data transmission (i.e. “error detection”).  Used for telephone modem transmission, RAM usage, etc.  The term refers to the use of a so-called parity bit which is added to every data unit (typically 7 or 8 bits).  The parity bit for each unit is set for either odd or even, so that when the number of bits received is unequal to the ones sent, the receiver knows that there is a transmission error.  As you can imagine, it is not foolproof, and it does not actually correct errors, as does ECC or EOS.

PARSE:  Just like parsing an English sentence means to break down the sentence into it’s component parts, parsing in computers means to analyze or separate code (e.g. input) into more easily processable components.

PARTITION: A physical section of a hard disk drive.  There must be at least one section and there can be more.  Each partition must be formatted (e.g. into FAT, FAT32, NTFS, Linux).  There are three types of partitions - Primary (bootable); extended and (within extended) logical. Partitioning refers to the practice of dividing the storage space on a hard disk drive into separate data areas known as partitions. Each partition functions as a separate disk drive containing, for example, a second operating system, system recovery software or separate data files.  This facilitates backup, creates a barrier against viruses which infect the operating system, and allows operating multiple systems.

PASCAL:  An early 3GL programming language (designed primarily for instructional purposes around 1967-8 by Nicholas Wirth) which was very structured, and has pretty much been superceded by C++ and Java.   

PASSIVE: Relies on whatever current comes from the connecting cable to a device, as opposed to active, which uses outside current to power the device.

PASSWORD: See this LINK.

PATH:  A common computer term referring to the description of the location of a file within the directory heirarchy of the hard drive (e.g. folders, subfolders, sub-subfolders).  Thus, a document may have the path: “C:\User\Documents\websites\glossaryP”.  It’s imperative for you to know the path of a saved file because, without it, it cannot be easily retrieved. Also, sometimes, a reference in graphic design and desktop publishing programs to the line that may be drawn around a graphic, perhaps to select it for editing.

PATCH:  A remedy or repair to existing code (program), usually to fix an error or vulnerability to a virus or intrusion.  

PAYLOAD:  Malware or virus programs that wreak havock on your computer, often delivered by e-mail or installations. See Spyware.

PAYPAL:  One of the first and arguably most famous e-commerce web businesses allowing payments and money transfers to be made over the Internet as an alternative to paper payments for purchases, auctions, etc.

PBX:  Stands for Private Branch Exchange, a private telephone network used primarily in offices, which share a certain number of outside (public) lines for making telephone calls external to the PBX.  Offices use this type of system because it is significantly less expensive than connecting external telephone lines to each telephone in the organization, and it takes only a couple of digits to communicate between telephones within the organization.  A variation of PBX called centrex uses all switching at the local telephone office rather than at the company’s premises.

P2P:  Stands for “Peer to Peer”, a type of network characterized by each computer (“node”) having equal capabilities (as opposed to client server networks (a/k/a “hub-and-spoke”)) on which the responsibilities all reside on the server).  An example of P2P architecture would be the internet file sharing such as Napster, Gnutella and BitTorrent. See warnings about P2P in the SECURITY page.

P3P: Browsers such as Internet Explorer purport to block third party cookies from sites that don’t post a particular type of policy statement called the Platform for Privacy Preferences (a/k/a “P3P”) which is a protocol allowing websites to declare their intended use of the information they collect.

PC:  Short for ”Personal Computer”, but referring to DOS and Windows (Microsoft) based computers, as opposed to MACs (Apple OS) based computers.  Originally this term distinguished between very large mainframes and desktop computers, but more recently distinguishes between OSs. The very first PC was the Alto, developed at Xerox’s famed Palo Alto Research Center (get it?) by Charles P. Thacker and his team.  This machine so impressed Apple’s Steve Jobs that he modeled the Macintosh computer on it.  In the 1980s, IBM introduced the PC & PC, Jr.  For more about the first computers, click HERE.

PCB:  Short for Printed Circuit Board.  A thin plate on which chips and other electronic components are placed, usually soldered.   Computers have such boards, sometimes called cards, riser boards or adapters.  Virtually all printed circuit boards are made of fiberglass (glass-epoxy) resin, which is naturally greenish or tan in tint, over which a copper film has been deposited, which has then been partly removed by etching with either ferric chloride or sodium persulphate.  Why are PCBs mostly green?  Although other colors are available, it’s true that they’re usually green. The general consensus is that the color green actually comes from the soldering mask material which has traditionally been applied to the board after it has been “printed” (the copper coating over the entire board has been removed to create the “circuit lines” on the board) for the purpose of preventing any stray solder from bridging the board circuits and also preventing corrosion, scratching or damage while still remaining transparent.

PCI:  Stands for “Peripheral Component Interconnect”.  Also, “Practical Communications Interface”. This is the most common type of “slot” (receptacle) in a computer’s mother (main) printed circuit board into which other printed circuit boards (often called “riser” cards or “expansion” cards or “controllers”) are inserted.   PCI cards add specialized capability to the computer’s main board for operations such as sound, video and modems.  There are a number of size variations of PCI cards, including compact, mini, low-profile and X.  Other, less common, types of expansion slots and cards are ISA (“Industry Standard Architecture”), EISA (“Extended Industry Standard Architecture”), MCA (“Micro Channel Architecture”), AGP (“Accelerated Graphics Port”) and CNR (“Communication and Networking Riser”).  Click HERE for photos of common slots.

PCI DSS: Stands for “Payment Card Industry Data Security Standard”.  This standard, which was created in 2004 jointly by Visa, MasterCard, Discover and Amex, is a widely accepted set of policies and procedures intended to optimize the security of credit, debit and cash card transactions and protect cardholders against misuse of their personal information.  The six “objectives” of the standards are (1) a secure network (e.g. firewalls, passwords), (2)  protection of customer data (e.g. encryption), (3) protection against hackers (e.g. anti-virus, anti-spyware), (4) restricted access to information (e.g. IDs, passwords), (5) system monitoring and testing, and (6) development and maintenance of a formal information security policy.

PCM: Stands for “Pulse Code Modulation” which is a technology whereby standard audio signals (which are represented by waveforms) are converted into digital audio signals (which are represented by 1’s and 0’s) with almost no compression.  The PCM signal is converted back to analog form for distribution back to the speakers.  PCM should not be confused with either Dolby Digital or Bitstream, both of which encode in a different matter and which are compressed.

PCMCIA: Stands for “Personal Computer Memory Card International Association.”  This is an organization that has developed a standard for small, credit-card sized devices, called PC Cards that provide memory, cable, telephone, wireless and other capabilities, mostly for laptops that have a special PCMCIA slot for inserting these cards.

PCoIP: A VMWare protocol which improves performance over low-bandwidth networks.

PDA:  Personal Digital Assistant.  These devices, manufactured by Palm, Compaq, Apple, Microsoft and others are basically the size of a deck of cards and contained a calendar, word processor and other programs.  Early PDAs did not contain a cell phone feature, newer ones do.  While they were popular several years ago, PDAs have been overtaken by Blackberry phones, iPhones and other full-featured cell phones, which include these features.

PDF:  Short for “Portable Document Format”, developed by Adobe Systems, this format is used to capture items developed using a variety of desktop publishing programs, allowing them to appear on the recipient’s computer as they were intended.  Adobe Reader, a free application from Adobe, allows the viewing of the program.  The full (paid) program, Adobe Acrobat, allows for creating and editing files in PDF format.

PDMI: Portable Digital Media Interface.  A 30 pin connector used with many tablet computers. Not the same as Apple connector.  See, connector photos.

PDU: Power Distribution Unit.  Any device which provides electrical power to data center equipment such as servers, storage devices and networking components.  There are many kinds of PDUs, including Basic (simple), Dual Circuit Intelligent (creating redundancy), Metered (monitors the amperage so it is not exceeded), Switched (ability to manage the load through a network connection) and ATS (Auto Transfer Switch)(ability to monitor with redundancy).

PEBKAC: A (geek derogatory) term which means “Problem Exists Between Keyboard and Chair, i.e. User Error.  Techs may use this term between themselves in front of a client to communicate the problem, much like other people will speak another language.  Kind of like PICNIC (Problem In Chair Not In Computer) or ID-iot eror.

PEER-TO-PEER: A type of computer network in which all computers are equal, because each computer can be both a server and a client, depending on whether it is sending or receiving information.  The largest peer-to-peer network is, of course, the Internet.  This is the most common type of network, and it differs from the hub-and-spoke type network commonly used in intranets (e.g. offices), where a server (host) computer communicates with relatively dumb workstations (spokes). See also, Networks, Host, P2P.

PEN TESTING: Short for “penetration testing”.  Testing, usually by consultants, to determine if they can penetrate the security measures you have taken to protect your computer(s) from intrusions and viruses.  Internal corporate pen testing groups are sometimes known as “red teams”.

P=NP:  A formula which computer science theorists regard as the central theoretical question of the day.  P represents the collection of mathematical problems that a computer can solve in a reasonable amount of time.  P actually stands for polynomial, representing a problem that only gets somewhat more difficult as the numbers get larger (the opposite of exponential, where the time needed to solve bigger problems grows quickly unreasonably large).  The other side of the equation, NP, represents those problems whose answers can be verified within a reasonable time.  The question is whether these two are the same.  It’s not as easy as you might think: It is easy to multiply two large numbers for a total, but not so easy to verify the result by starting with the product and working backwards to find the factors which produce that result.  Most theoreticians don’t think that P=NP, but they’re not absolutely sure about this.  Hope that they’re correct, as most computer encryption routines hinge on the difficulty of factoring large numbers.  Even after 40 years, there is no answer in sight to this formula; if you do solve it, you can apply for the $1 million reward from the Cray Mathematics Institute.

PERIPHERAL:  Any hardware connected (cabled or wirelessly) to the main computer (CPU).  This includes the monitor, printer, scanner, external drive, etc.

PERL:  See CGI.

PERVASIVE MEMORY SCRAPING:  A type of hacking of encrypted data, designed to capture PII (see below).  Usually occurs directly on the server, often internally through administrator accounts.  Where there isn’t end-to-end encryption, sometimes data resides briefly in volatile memory (RAM) and can be hacked from there.

PHISHING:  See Spyware.

PHONE:  See Telephone.

PHONENET:  An alternative cabling scheme using telephone wiring in homes for networking. Originally developed by Farallon Computing and first used for Apple computers, it has been mostly discontinued.  See AppleTalk.

PHOTO BOMBER:  Someone who either intentionally or unintentionally ruins an otherwise normal photo by, perhaps, making faces, gestures, getting naked, wearing a costume, etc., usually in the background of the photo.  Also, a TAG BOMBER tags a person in an ugly/awkward/compromising photo that they wouldn’t want other to see, uploading it to multiple social networking sites.

PHOTOSHOP:  An professional program from Adobe used for editing photographs and graphics that has become so popular that it is often used as a verb (“...that’s a Photoshopped photo”) to indicate a “doctored” image.

PICASA:  A program that can be downloaded from the Internet which edits, organizes and shares photos over the Internet, acquired by Google and merged into Google+ as Google Photos in 2011.

PICO:  Pronounced “Pee-Ko”.  A cellphone device or feature on a cellphone that can project photos (using laser technology), videos and graphics onto flat surfaces.  Not terribly bright (maybe only 5 lumens) and not terribly large (maximum 2-3 feet square at a maximum 6 ft distance), the technology is constantly improving.  Other than as a must-have-it-first feature for the Sharper Image crowd, I could see its usefulness to review photos where there is no computer or printer available, make an impromptu Powerpoint presentation to an important prospective client, or to watch a movie on the seatback of an airplane seat, but generally its overall usefulness escapes me so far, aside from the fascinating technology.  A similar device has been introduced by Blackberry, the “Presenter,” which is a separate bluetooth device plugged into a monitor or projector, eliminating complicated connections to a PC, and enabling the user to wander the room using the Blackberry as a remote (about $199 from shopblackberry.com)... Also, the Samsung HO3 projector (about $299).

PII:  Stands for Personally Identifiable Information. This includes such things as full name, mother’s maiden name, social security number, medical and employment records which, if released, could compromise your security.

PILCROW:  ¶ .  The typographic symbol or glyph used as the ”paragraph” symbol.  Also called the paragraph sign, paraph, or alinea.  It is used extensively in word processing and desktop publishing software, as well as in legal citation and proofreading.  As with many marks, its derivation is unclear.  Many say that it originally started with the letter “C”  (for capitulum or “chapter” in Latin) with double slashes through it, indicating the usual way that a scribe made his notes.

PIN:  The tiny metal “feet” on the underside of a silicon chip (like a RAM or video chip) that enable them to be attached to a circuit board.

PIN NUMBER:  Personal Identification Number:  A code that must be entered in order to access a program or computer.

PING:  A web utility that is used to determine whether a specific IP address is accessible, usually for internet troubleshooting.  It does this by sending a packet (ICMP Message) to the specified address and waiting for a reply. Ping’s author says that the name comes from “the sound that sonar makes”.  See loopback for a similar utility used with telephones.

PING POWER PIPE:  A colocation arrangement by which an ISP provides space, power and a link to a customer, all at their own facility. The ISP is only responsible for assuring that the servers are running.

PIO:  Programmed Input/Output - see DMA for a complete explanation.

PIPE:  A method of passing information from one computer to another, either in a network or over the Internet, through a temporary software connection. Some pipes are larger than others, influencing bandwidth.  Think of it like this:  If you have a tank with 100 gallons of water and you want to empty it, you have to consider the diameter of the pipe you will use to empty it in order to determine exactly how long it will take.  The faster, of course, the better.  So, if you use a 3/4 inch diameter pipe, no matter how much pressure you exert, it will still take an hour to empty the contents of the tank.  But, if you use a six inch diameter pipe, it’ll only take ten minutes.  The larger the pipe, the faster the speed.  It’s the same with computer bandwidth:  The larger the pipe, the faster the transfer speed.  That’s why the advent of cable, FIOS and DSL have made it possible to view streaming videos over the Internet without the “choppiness” that occurred when using the slower (i.e. smaller “pipe”) dial-up connections.

PIPE KEY:  A computer keyboard character (“ | “) which is a vertical line, also called a verti-bar, vbar, stick, think colon, divider line or vertical line.  It is usually found as the shift character above the backslash character on the top right of the keyboard characters.  It has various usages in computer programming and mathematics and is sometimes just a typographical divider.  The name for the pipe character is derived from its usage in Unix shells, where it notates the I/O Pipeline construct.  This character is not the same as the “(vertical) broken bar” (sometimes called a “parted rule”) unicode character    (“ ¦ “) which has a different mathematical and programming use and is rarely used.  The pipe is somewhat similar, however, to the Interpunct (“middle dot”) character (“ · “), which is often used as an interword separator, originally in Latin inscriptions (DONA ·EIS·REQVIEM) and also sometimes in the Mac OS X system and Unicode.

PIVOT TABLE OR CHART:  This is a feature found in spreadsheet (e.g. Excel) and database (e.g. Access) programs which allows you to reorganize (“pivot”) selected columns or rows of data into a separate table or chart to view it from a different perspective.  It doesn’t alter the database itself, just changes the view.  Especially useful for viewing select parts of very large databases.

PIXEL:  This is a contraction for “picture element”, which is a single point in a graphic image.  Pixels can vary in intensity, and they are combined to display a graphic image.

PKI: Public Key Encryption.  This differs from the private encryption that you may use on your own (see Encryption) in that with PKI a public key is provided by some designated authority as an encryption key that, combined with a private key derived from the public key, provides the encryption.  The use of combined public and private keys is known as asymmetric cryptography. 

PKZIP: A program used to compress files, usually for transmission over the internet or between computers. See also, ZIP.

PLACECASTING:  Also known as Proximity Marketing. This is the wireless transmission of advertising content for a particular “place” over suitably equipped internet appliances, such as smart phones.

PLATFORM: A computer system on which application programs can be run.  The platform consists of both the software operating system (e.g. Windows XP, Mac OS X, Linux, Unix) as well as the instruction set for the processor (e.g. Intel PIV), on which it operates.

PLENUM:  A type of cable (coax and twisted pair) meaning that it can be used inside walls, heating and a/c ductwork, suspended ceilings and raised floors where fire safety is a concern, as it will not produce toxic gas when it burns.  Click HERE for more.

PLESK: A software package used for commercial web hosting, providing automation for those tasks.

PLOTTER: A printer that makes line drawings like blueprints on large paper through the use of several automated pens.  Unlike other printers, a plotter can draw continuous point-to-point lines directly from vector graphics files or commands.  Plotters can be drum type, flatbed type or electrostatic.  Plotters were the first type of printer that could print in color and render graphics and full size engineering drawings, using CAD and CAE, but they are quite expensive.

PMP: Stands for Project Management Professional, a certification (by exam) by the Project Management Institute which purports to be the industry standard for demonstrating competence and a solid foundation of project management skills.

.png: A type of graphics file format which preserve “transparency.”  That is, it is used to layer items without having a white box around the object. .png can be either interlaced or not.  Interlaced means that the file is saved with several resolutions built in to the file.  You will recognize such an image because, as it loads, it becomes increasingly clearer in seven waves.  Here’s an example of the difference between a .png and a standard .jpg file:  

POLYMORPHISM: No, it’s not a contageous disease.  Rather, it is a technology that makes rootkits (See Spyware) almost impossible to find using ordinary anti-virus and spyware programs.  Polymorphism techniques allow rootkits to rewrite core assembly code; the only hope for finding rootkits using polymorphism would be a technology that searches deep into the operating system and then compares the results to a known good baseline of the system.  A polymorphic virus is one that changes its virus “signature” (i.e. its binary pattern) every time it replicates, and then infects a new file in order to keep from being detected.  See also, signatures.

POST: An integral part of the BIOS (but not in UEFI) which stands for Power On Self Test, the purpose of which is to detect the computer peripherals such as the keyboard, RAM, printer and other hardware, as well as the hard drive, and determine that it is running properly.

POTS: Telephone slang for Plain Old Telephone Service.  Refers to the old analog land line phones.

POUND: The “ # “ symbol; see Octothorpe.

POWERLINE: A type of networking characterized by adapters which plug into electrical outlets to connect the network hardware.  See this LINK for more.

POWERSHELL: A Windows feature which concerns remote management, ability to run background jobs and various custom scripts called “cmdlets” usually written in VBScript.  Due to the complexity of this feature, it is used by mostly large organizations.

POWER WHIP:  Industry slang for a power source that connects the building’s electricity to the systems furniture or cubicle.

PND: Portable Navigation Device, such as a smart phone or a GPS .

PNP: Plug and Play.  A part of the Microsoft O/S since Windows 95 that enables the operating system to recognize and install various hardware automatically, as opposed to manually.  Much more reliable than it was at its introduction, when it was dubbed “Plug and Pray”.  Do not confuse with Universal Plug and Play Service (“uPNP”) which is a way that Windows XP can detect new network resources, not local hardware resources.

POD: An acronym used for as part of the name for the Apple iPod which, according to Apple, stands for “Portable on Demand”.

PODCAST: A portmanteau of the words POD and broadCAST.  First promoted by Apple in late 2004 (but designed by Adam Curry (of MTV fame) and David Winer), it is a digital media file that is downloaded from a streaming Internet source onto a computer, then directly onto a digital media device like an iPod (hence the “pod” in the name) or other media player (like an MP3) to be viewed. It’s kind of like an online pre-recorded TV or radio program over the Internet.  Used originally to create “feeds” (subscriber downloads of updated information) from news and radio shows, it now extends to TV and even commercials.  Lots of websites have podcasts.  Directories of some of these sites can be found at podcast.net, Yahoo!Podcasts or Apple iTunes.  What makes them so popular is the ease of creating a podcast and the ease of regularly downloading them.   You have to subscribe to a podcast using a software program called a “podcatcher” or sometimes an “aggregator”.  The podcaster regularly checks the feed for any new content that has been posted and, when it finds it, automatically downloads it. Next time you plug in your MP3 player, it’s downloaded.  Further, most podcasts are free, can be replayed, don’t result in spam and are commercial free. And, you can always unsubscribe.  Despite the rise of social media, podcasting is still quite prevalent.

POE: Power Over Ethernet. The delivery of both data and power over common (Cat 3, Cat 5) twisted pair cabling, such as when one or more pairs of Cat 5 cable are used for telephone.  PoE is used for various devices, such as cameras, connected to the system and managed through a PoE switch.  PoE is a subset of the 802.3 ethernet standard initially defined by the IEEE in 1983.  The original PoE standard (802.3af) was ratified in 2003 and supports up to 15W per port at a nominal voltage of 48V DC.  Un updated standard (802.3at, sometimes known as PoE+) currently under consideration by the IEEE would increase the per port power capacity to 30W over CAT 5 and higher cabling.  See also, VoE.  The single cable reduces cabling, power supply boxes at outlets and service outages.

POINT: See, Fonts.  A measure of type size, one inch equal to 72 points.  Because the measure is derived from earlier mechanical printing, the point size was actually derived from a measurement of the type body (the metal on which the type face was printed on) rather than the size of the type face itself.  As a result, the point size may substantially vary from one typeface to another, since not all typefaces occupy the same size type body.  For example, see the following variety of typefaces all shown in exactly the same point size:

POP3:  Incoming e-mail server. It’s where your mail is stored before it is picked up by the host (the part of the e-mail address to the right of the @ symbol).  POP stands for “Post Office Protocol” [a protocol is a standard way of communicating across a computer network, i.e. it is the “language” of the network].  The other most popular e-mail protocol is IMAP, which stands for Internet Message Access Protocol.

POPULATE: With respect to computer hardware, this means to plug in all chips and other components onto the main circuit board.  A “fully populated” board is therefore one that contains all the devices it can hold.  Respecting software, it means to incorporate all of the necessary information into a program so that it can perform its function.  For example, in order for a database to execute and produce a report, it must first be populated with all of the raw data required to define and then execute that report. 

PORT:  This term has both a software and a hardware definition. 

When applied to hardware, a port is generally a specific place for a physical connection between the main computer and a peripheral device (See, PCI, above).  Most computers can have a maximum of 3 parallel, 4 serial, and 2 PS2 ports, although newer computers may have none of these, only USB ports.  DOS assigns the names LPT1, LPT2 and LPT3 to the parallel ports, which are usually used for printer (the designation LPT actually means “Line Printer”). The pseudonym for LPT1 is PRN, the first and most common printer port.  COM1, COM2, COM3 and COM4 are the DOS names for the serial ports (COM means “communications” port).  USB (Universal Serial Bus) ports are called USB ports; there can be (theoretically) up to 127, practically now more than 6.  PS2 ports are used for keyboard (purple) and mouse (green) connections, so called because these ports were introduced in 1987 with IBM’s Personal System/2 line of computers.  You should consider the number and type of ports when building or purchasing a computer.  For more on this, see the discussion at CASES.

Respecting software, a port is a “logical” connection place into which a client program specifies a server program on a network computer (such as TCP/IP).  An internet port is a numeric address that online sites use to communicate with your PC.  Such ports can be Open, Closed or Stealth (closed and completely invisible to outsiders).  Ports have assigned numbers, between 0 and 65,536, assigned by the Internet Assigned Numbers Authority (“IANA”) and are divided into three ranges:  Ports 0 to 1023 are always reserved for use by the IANA, are known as the Well Known Port Numbers, and include standard default ports like HTTP (port 80), FTP (port 21) and SMTP (port 25).  The second range is the Registered Port Numbers, containing Ports 1024 through 49,151, generally assigned to be used by ordinary programs and user processes that are executed directly by users.  The third range is the Dynamic or Private Port Numbers, ranging from port 49,153 through 65,535, generally for use by applications and processes not initiated by the user.  Because of this, the upper port range has been used by Trojan Horse and Back Door programs and is often blocked by administrators. Most ports are designated as either TCP or UDP.  TCP ports are used for such things as web sites and e-mail.  UDP ports  are used when a transmission doesn’t need to have confirmation that a packet has arrived at its destination.  For example, in home networks, UDP ports are used mostly for home gaming (for example, Xbox uses UDP ports 88 and 3074 to connect with the Xbox Live Service).  Normally, a port is closed when there are no system services using it or listening to it, protecting your system from outside attacks.  But there are always malicious hackers who can find a way in, so additional protection (hardware and software firewalls) may be advisable.  Click HERE to learn the significance of the number 65,536.

PORTAL:  A term, pretty much synonymous with Gateway, for a World Wide Web site that acts as a major starting point or “anchor site” for users when they connect to the Web, creating a single point of access to information connected from many sources.  Portals can be divided into general portals such as Yahoo, Excite and the like and niche (specialized) portals, such as garden.com & wine.com.

PORT REPLICATOR:  See Dock.

POST: Power On Self Test.  A diagnostic test sequence run by a computer’s BIOS, after the power is turned on, which determines if the computer’s RAM, drives and peripherals are working and, if so, allows the computer to boot.  The POST test is accompanied by a series of long and short “beeps” which indicate whether or not specific hardware is working or failing; the interpretation of the beeps varies with each manufacturer of the computer’s motherboard.  Secondary meaning: A public message sent to a blog, as in a comment to the original post (part of a  “thread” of posted comments), is a “post”.

POSTINI: Sounds like some sort of Italian cracker.  But it’s not.  It’s actually a variation of the Italian word for “postman.”  Postini is used to indicate a type of e-mail security which is distinguished because it filters the e-mail before it reaches the destination box; It is used mostly by companies which manage their own e-mail servers.  Named for the electronic mail security company, founded in 1999, based in San Carlos, California bearing this name.  It was purchased by Google in 2007 and is used in Gmail.  It is a “hosted” service which doesn’t require the user to install any special software or hardware, as all the incoming and outgoing data is hosted and processed on the Postini servers first.

POSTSCRIPT: Also, Encapsulated PostScript.  See FONTS, above.

POWERSHELL: A command-line shell and associated scripting language from Microsoft, originally dubbed “Monad”.  Most users will never use this, just C:/cmd.

POTS: Stands for “Plain Old Telephone Service”.  Your basic old fashioned wired land-line telephone service.  Copper wires, no DSL, no FIOS.

PPSD: Stands for “Personal Portable Security Device”.   Combines the flash storage of a USB pen drive with the access and secure storage capabilities of a smart card, using cryptographic encryption and strong user authentication.

PREDICTIVE SEARCH: A search which lists suggestions as you type the query.  As you continue typing, the suggestions become more and more specific.

PREFETCH: A file in Windows and other programs into which data or instructions, often when downloaded off the Internet, are placed into higher-speed storage or memory before they are actually processed.

PRINTERS: Generally, any piece of computer equipment which prints text or graphics, or both, onto paper of other media.  Click HERE for more information.

PRIVACY: With the exception of certain specialized areas (e.g. patient records), there is NO RIGHT OF PRIVACY ON THE INTERNET.  Especially from the Government.  See Social Networking, Laws, Carnivore, Echelon, etc.

PRIVATE BROWSING MODE: Also euphemistically known as “porn mode”.  A feature on some browsers that allows the user to browse in a session that does not save any data (e.g. history) from the browsing session.

PRIVILEGE: Sometimes also called “Permission.” A permission to perform an action or grant access on a computer system, i.e. access a drive or a printer.

PROCESSING: The use of a computer to manipulate data (words, numbers, etc.) according to instructions (a program) to achieve a desired result.

PROCESS: When you look in the Windows Task Manager and see a list of “processes,” for example, it simply means a list of programs that are running at that time.  It may include many executable programs that you may not understand, as they may be part of the operating system, but they are programs.

PROCESSOR: The logic circuitry that responds to and processes the basic instructions from the operating system that drive a computer.  This term has generally replaced the term CPU.  The “chip” that is embedded in the processor circuitry that is the brains of the processor is often called the “microprocessor.”

PROGRAM: Generally, refers to application software for end users. See, Applications.

PROMIS: Software developed by Inslaw, Inc. in the early 1980s for the U.S. Dept. of Justice (Prosecutor’s Management Information System) originally to keep tabs on prosecutors’ caseloads, but which allegedly morphed into spy tracking software.  The DoJ allegedly put Inslaw into bankruptcy and stole then modifiedwith backdoor capabilities for covert intelligence operations.

PRNG: Stands for cryptographically secure PseudoRandom Number Generator. It was developed by Bruce Schneier and Niels Furgeson and is named after and sometimes also called Fortuna, the Roman goddess of choice .  PRNG is composed of three sections:  The generator itself, the entropy accumulator, which “reseeds” the generator by collecting genuinely random data, and the “seed” file itself which enables the computer generator to work.

PROTOCOL: The “language” (actually, more like a set of communications standards or rules) used by a network for communicating across the network.  For example, TCP and POP3 are protocols.  Protocols had to be developed in the early days of computer communication in order to prevent too many proprietary ways of sending and receiving data over the Internet, thus “standardizing” network communications for everyone.  To get an idea of the hundreds of protocols in use, click HERE for a directory listing of common protocols.  See, e.g. SDN.

PROXIMITY MARKETING:  See, Placecasting, above.

PROXY SERVER:  A form of firewall.  A proxy is someone who performs some action on your behalf; a proxy server performs network transactions on your behalf, most commonly web transactions.  The proxy server will take requests from your web browser, get the web pages from the internet on your behalf, and return them to your browser.  Because the proxy server can perform authentication to see who is requesting the web pages and logs the pages requested, it provides some level of protection

PS: Stands for PlayStation, usually with a version number at the end, such as the current version, PS3.  First released in 2006 and now part of the seventh generation of game consoles, PS3 is produced by Sony, and competes with Nintendo’s Wii and Microsoft’s Xbox.  A significant distinguishing feature of PS3 is the PlayStation Network, a unified online gaming service which relies on players, as opposed to professional developers, to contribute to the games, as well as the ability to use Blu-Ray disks. The Vita version, introduced in 2012, combines the gaming console with social networking in a smart phone interface.

PS2 Port:  See, ports, above.

PSTN:  Public Switched Telephone Network, i.e. the “Telephone Company”.  See DEMARC.

PSEUDOCODE:  A detailed yet readable description of what a computer program or algorithm must do, expressed in a formally-styled natural language (say, English) rather than in a programming language. Once the pseudocode is accepted, it is rewritten using the vocabulary and syntax of a programming language (e.g. C++).

PSU:  Power Supply Unit.

PTE:  Page Table Entry. A 32-bit entry into the Windows paging file table which defines the mapping of virtual memory to physical memory. See Page File, above.

Public vs. Private:  Click HERE for a discussion of public and private IP addresses and how they operate.

PUBSTRO:  Refers to a computer that has been hacked and had an FTP server installed.  The FTP server is then used to transfer and spread WAREZ (copyrighted software), usually illegally.

PUE:  Power Usage Effectiveness.  A standardized measurement comparing how much of the total energy in a data center is used by the IT equipment compared to how much is used for heating, cooling, lighting and other infrastructure needs (i.e. total facility power divided by IT equipment power) with 1 as a perfect score (meaning that  all data center power would be completely consumed by IT hardware, with absolutely no waste).  Used by large IT organizations to determine energy consumption and reduce the cost.  Many large companies score as low as 1.2; Google has reached 1.15 in some locations.

PUNCH CARD:  Invented in 1884 by Herman Hollerith (a German-American statistician) of the Tabulating Machine Company, which was joined by Thomas J. Watson, Sr. in 1914, and which subsequently (1924) became known as IBM.  Sometimes called, in fact, a “Hollerith Card”.  A stiff paper card, about 90mm x 215mm, commonly having 1 character per column and 80 columns per card, onto which were punched rectangular holes (“chads” being the paper bits cut out of the holes, remember the 2004 election?) to represent letters, numbers or code, were read by a computer, through a “reader” with a large card “hopper”, in order to process data.  Because holes could corrupt the data to be read, they usually contained the printed warning not to “fold, spindle or mutilate”.  (The myth that the cards were rectangles so that they fit into cash register drawer trays was disproven.)  Hollerith invented and patented the punch cards in order to create a machine to tabulate U.S. census data more efficiently than the hand methods used up until his invention.  His great breakthrough was his use of electricity to read, count and sort the punch cards with the relevant census data, so that the machines, which were first used for the 1890 census, accomplished in one year what would have taken nearly 10 years by hand tabulation (See below).    He got the idea from combining the idea of a train conductor punching tickets with a machine created by a French silk weaver named Joseph-Marie Jacquard, which automatically controlled the warp and weft threads on a silk loom by recording patterns of holes onto a string of cards.

From left to right:  Punch card, hand punch card machine, electric punch card machine, punch card reader

PUNCHDOWN BLOCK:  (Also, punch block, or quick-connect block).  A type of electrical connection used in computers and telephony in which solid copper wires are punched down with a special tool into short open-ended slots known as insulation-displacement connectors.  They are used because there is no stripping of wiring, connectors to fasten or screws to loosen and tighten.  For photos and more definitions, see 66/110 Block.

PUPPET:  One of the most popular cloud server-management software apps, it greatly reduces the number of steps and lots of necessary coding required to set up a server with the right software, storage space and network connections, particularly for cloud servers.  It is most useful in setting up and managing the tens or even hundreds of thousands of computers in cloud networks more easily.  It got the name because Luke Kanies, founder of Puppet Labs, decided it was like a puppet master, pulling on strings to give computers particular personalities and behaviors.  See also, Chef.

PUSH TECHNOLOGY:  Synonymous with “Webcasting” or sometimes “Netcasting.”  This is the prearranged periodic updating of data (i.e. news, weather, podcasts) to a computer desktop or an internet enabled cell phone screen over the Internet.  It’s called “push” technology because the Web server ostensibly “pushes” information to the user rather than waiting until the user specifically requests it.  This technology is included in Internet Explorer and many other programs (BackWeb, Castanet, Headliner, Pointcast, etc.)

PXE-ROM:  Preboot Execution Environment.  This is an Intel legacy implementation, usually on computers containing an Intel PXE-ROM network card.  At boot, the program reflashes the network card.  Newer cards retain the
DHCP, don’t need to be reflashed each time.  Can usually be disabled on newer machines.

Python:  This is a general purpose programming language.  It’s design philosophy emphasizes programmer productivity and code readability.  This is an open, somewhat formally specified development model, initially released by Guido van Rossum in 1991.

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