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Glossary P...


PACKET SWITCHING A data transmission protocol where information is split up into separate packets, each with some identification data showing where it's going and how it fits back together again. It can then be sent via whichever network route is most efficient (different packets may go by different routes) before being reassembled again when it reaches its destination. This is the way the Internet works.
PAL (pronounced "pell") Acronym for Phase Alternation Line.
PARALLAX The visual effect used when scrolling where objects that are further away appear to move more slowly than objects that are close by.
PARALLEL PORT One of the ports available on most computers to connect external devices that use parallel data transfer techniques where one byte of data composed of eight bits is transmitted in parallel over eight wires. See also Serial Port and Universal Serial Bus. While the connectors on older machines will be black, the connector has been coloured bright pink on more recent machines for easier identification.
PARALLEL PROCESSING Many of the high level work-stations utilise more than one CPU to perform the processing load, and machines equipped with transputer technology can have as many as 64 processors, all sharing the load, working in parallel. These types of systems have very complex operating systems and often have specialised applications, such as weather forecasting. In the future we can expect to see more parallel processing systems, oriented particularly towards 3D graphics rendering, probably in real-time.
PARENT WINDOW The window containing the icon used to open another window.
PARITY An extra bit calculated & attached to other bytes during the transmission of data to determine whether any errors occurred during the transmission. Also used by storage devices such as hard drives to ensure that no data loss has occurred.
PARTITION A sub-division of a hard disk, where the available space has been divided into one or more discrete logical disks. For example, an 100Gb hard disk could be partitioned into 20Gb for the AmigaDOS operating system software and associated utility programs, 40Gb for Application software, and 40Gb for application data and storage. The advantage of partitioning in this way means that in normal use, only the last partition needs to be backed up regularly, the first whenever you make system changes, and the other backed up when new software is added, and even then is should not matter too much as you can simply re-install from the original floppy disks.
PASCAL A structured programming language developed by Nicklaus Wirth that is particularly popular with academics.
PATH The route that the computer's Operating System must take to find a particular file. The path of a file usually includes the device, disk name, or location and all of the directories and sub-directories that lead to that file. It can also be used by the Operating System to locate one or more files from a poll of resources where programs reside, which has the effect of con-catenating all the physical directories into one logical directory or library.
PATHNAME The path of a file including the device, disk name, or location and all of the directories and sub-directories that lead to that file.
PATTERN MATCHING An Operating System function that enables you specify file and directory names by using patterns rather than specifying them individually.
PAULA CHIP A custom chip responsible for all of the sounds generated from a Classic Amiga. It provides four voices of sound output configured as two stereo channels with nine octaves over a range of complex waveforms, and uses both amplitude and frequency modulation. It also handles many of the input/ output tasks such as disk and interrupt control, the mouse, joystick and serial ports. This chip has been superceded by Mary in the AAA chipset.
PC (pronounced "P-C") Acronym for Personal Computer.
PCI (pronounced "P-C-I") Acronym for Peripheral Component Interconnect.
PCI-BUS (pronounced "P-C-I Buss") The I/O Bus used for Peripheral Component Interconnect operations.
PCMCIA (pronounced "P-C-M-C-I-A") Acronym for Personal Computer Memory Card International Association, who defined a standard for peripheral devices on notebook computers. Devices using this standar were originally known as PCMCIA devices, and was subsequently changed to 'PC Cards'. A later revision of the PC Card is known as 'CardBus'.
PCX A graphics format defined by the ZSoft Corporation for use with their PC Paint Brush product, which runs on MS-DOS systems. PCX images may contain from 1 to 256 colours, including the special palettes for the EGA and CGA display cards, but can also contain 24 bit-planes of information. Images in this format generally have a suffix of ".pcx".
PD (pronounced "P-D") Acronym for Public Domain.
PDA (pronounced "P-D-A") Acronym for Personal Digital Assistant.
PDF (pronounced "P-D-F") Acronym for Portable Document Format.
PEBIBYTE (abbreviation "PiB" 1,125,899,906,842,624 (250) bytes, and is the unambiguous name for 'Petabyte to denote the true binary value.
PENTIUM© The Intel Pentium provided greatly increased performance over the 80486 chips that preceded it, due to several architectural changes. Roughly speaking, the first Pentium chips were double the speed of the 486 chips of the same clock speed, and could be run at much higher clock speeds than the 486. The following are the key architectural enhancements made in the Pentium over the 486-class chips (note that some of these are present in Cyrix's 5x86 processor, but that chip was developed after the Pentium):
  • Superscalar Architecture: The Pentium is the first superscalar processor; it uses two parallel execution units. Some people have likened the Pentium to being a pair of 486s in the same chip for this reason, though this really isn't totally accurate. It is really only partially superscalar because the second execution unit doesn't have all the capabilities of the first; some instructions won't run in the second pipeline. In order to take advantage of the dual pipelines, code must be optimized to arrange the instructions in a way that will let both pipelines run at the same time. This is why you sometimes see reference to "Pentium optimization". Regardless, the performance is much higher than the single pipeline of the 486.
  • Wider Data Bus: The Pentium's data bus is doubled to 64 bits, providing double the bandwidth for transfers to and from memory.
  • Much Faster Memory Bus: Most Pentiums run on 60 or 66 MHz system buses; most 486s run on 33 MHz system buses. This greatly improves performance. Pentium motherboards also incorporate other performance-enhancing features, such as pipelined burst cache. The Pentium processor was also the first specifically designed to work with the (then new) PCI bus.
  • Branch Prediction: The Pentium uses branch prediction to prevent pipeline stalls when branches are encountered.
  • Integrated Power Management: All Pentiums have built in SMM power management (optional on most of the 486s).
  • Split Level 1 Cache: The Pentium uses a split level 1 cache, 8 KB each for data and instructions. The cache was split so that the data and instruction caches could be individually tuned for their specific use.
  • Improved Floating Point Unit: The floating point unit of the Pentium is significantly faster than that of the 486.

The Pentium is available in a wide variety of speeds, and in regular and OverDrive versions. It is also available in several packaging styles, although the pin grid array (PGA) is still the most prevalent. The original Pentiums, the 60 and 66 MHz versions, were very different than the later versions that are used in most PCs; they used older, 5 volt technology and significant problems with heat. Intel solved this with later (75-200 MHz) versions by going to a smaller circuit size and 3.3 volt power.

Pentiums use three different sockets. The original Pentium 60 and 66 use Socket 4. Pentiums from 75 to 133 will fit in either socket 5 or socket 7; Pentium 150s, 166s and 200s require Socket 7. Intel makes Pentium OverDrives that allow the use of faster Pentiums in older Pentium sockets (in addition to OverDrives that go in 486 motherboards).

PERIPHERAL Any hardware device connected a computer, be it as an internal card or as an externnal device. For example, an internal sound card or a printer are peripheral devices.
PERIPHERAL COMPONENT INTERCONNECT (acronym "PCI") An Intel designed bus type which enables 32-bit data transfer between the components on an MS-DOS machine similar to the *VL-Bus*, but PCI differs in that it uses additional components to help the processor in data transfer calculations, and is therefore significantly faster. Unlike the VLB card, more than one PCI bus card can be installed in a machine. Interestingly, PCI cards should work on different computer platforms that conform to the PCI standard, not just PC's.
PERL Practical Extraction and Reporting Language, a robust programming language frequently used for creating CGI programs on Web servers because it is faster than UNIX shell script programs, it can read and write binary files, and it can process very large files.
PERSONAL COMPUTER A moderately priced, general purpose computer, originally designed for a single user in a home or small-office environment. However, as the power and performance of PC's has evolved, they are finding their way into many other areas, sometimes replacing a large main-frame computer in business when used in conjunction with a file server and a LAN, and often given a title of `personal work-station' instead of personal computer.
PERSONAL DIGITAL ASSISTANT Battery powered computers that fit in the palm of your hand, offering speed and performance that is just a tad behind the mainstream, these clever devices currently fit into either of two camps - those that run Microsoft Pocket PC and those that run Palm's OS. They can communicate with desktop computers via USB, Infra-red or even Bluetooth and mobile phones, have full colour screens, memory modules up 512MB and even plug in cameras. Data can be entered by writing on the screen, tapping on an on-screen keyboard, or using an add-on keyboard, fold-up and portable of course.
PETABYTE (abbreviation "PB" 1,125,899,906,842,624 (250) bytes to be precise, but frequently used to mean roughly a thousand million million bytes (1015), or 1024 Terabytes. The unambiguous name 'Pebibyte' can be used for the true binary value.
PFS (pronounced "P-F-S") Acronym for Professional File System.
PHASE ALTERNATION LINE (acronym PAL) More commonly known by its acronym "PAL", it refers to the television standard used in most of Europe including the UK, part of Africa, India, Malaysia, Singapore, Australia, New Zealand and parts of South America. It has 625 lines running at 50 fields giving 25 frames per second, with a maximum of 210,000 picture elements (pixels) per frame. It uses a straight phase- and amplitude- modulation system for chroma but its V colour phase vector is switched 180 degrees on alternate scan lines. A sub-carrier frequency of 4.43 MHz is used. It was originally developed in Germany as an alternative to NTSC. In fact, there are several hybrid PAL systems in use, all of which are slightly different in operation. See also NTSC and SECAM.
PHP Recursive acronym for "PHP: Hypertext Preprocessor", PHP is a widely-used general-purpose open source, server-side, HTML embedded scripting language that is especially suited for Web development to create dynamic Web pages. In an HTML document, a PHP script (similar syntax to that of Perl or C ) is enclosed within special PHP tags. Because PHP is embedded within tags, the author can jump between HTML and PHP (similar to ASP and Cold Fusion) instead of having to rely on heavy amounts of code to output HTML. And, because PHP is executed on the server, the client cannot view the PHP code. PHP can perform any task that any CGI program can do, but its strength lies in its compatibility with many types of databases. Also, PHP can talk across networks using IMAP, SNMP, NNTP, POP3, or HTTP. PHP was created sometime in 1994 by Rasmus Lerdorf but during 1997, PHP development entered the hands of other contributors. Two of them, Zeev Suraski and Andi Gutmans, rewrote the parser from scratch to create PHP version 3 (PHP3).
PICA A standard unit of type size measurement, approximately equal to 1/6th of an inch, and can be further subdivided into points, where 12 points make 1 pica.
PICT A graphics format used by MS-DOS and Macintosh computers. Images in this format generally have a suffix of ".pict" and can be read using ADPro and various other Amiga programs.
PICTURE ELEMENT The smallest sized dot that can be controlled on the screen for a particular screen resolution, and is generally called a "pixel". Low resolution utilises 320 pixels x 256 pixels in PAL non-overscan mode which means 320 pixels across the screen with 256 pixels down the screen, giving a total of 81,920 pixels or picture elements. High resolution in similar mode has 640 x 512 (327,680) pixels. Other resolutions result in differing pixel sizes, and may require higher speed monitors to display them.
PING A program used in networking environments to test whether another computer is responding or can be seen over the network from the computer issuing the ping. The program got its name from the sound made by radar when an object was detected.
PIRACY The act of copying computer software that is not in the public domain but commercial or copyrighted material. In many cases, pirates also disable the copy protection mechanism used by the manufacturer to prevent illegal copying. This means that if you buy any software, and give a copy to a friend, you are breaking the law. When you buy software, you in effect buy the medium containing it (i.e. disks) and the right to use it, nothing more. Some programs specifically state that they may even only be used on a single machine at any one time. The act of piracy is condemned by Amiga Auckland and it will not be tolerated under any circumstances.
PIRATE A person who derives satisfaction, and sometimes money, by breaking the protection code often used to prevent copying of commercial software, and distributing or selling the copied version to others. Many pirates simply act as distributors, downloading cracked programs from overseas Bulletin Boards which specialise in pirated software, and may refer to themselves as importers to disguise what they do. They often include viruses on the disks as yet another means of self-gratification.
PIXEL Acronym for Picture Element.
PKAZIP (pronounced "P-K-A-zip") A compression program that is still popular in MS-DOS environments and is fairly rare now in the Amiga environment, but there is still the odd file around that has been compressed using PkaZip.
PLANAR BOARD A name given to the Motherboard in some MS-DOS machines.
PLATFORM GAMES A style of game where the action takes place on one or more surfaces that scroll either vertically, horizontally or both, almost like a maze, where the aim is to move around collecting points by battling nasties or saving damsels in distress. For example, Bubble Bobble, Gods, Flashback, Rainbow Islands, Soccer Kid, SuperFrog, Zool, and many, many others.
PNG (pronounced "P-N-G") Acronym for Portable Network Graphics.
POINT A typesetting unit of measurement equal to 1/12th of a pica (about 1/72nd of an inch). The height of all fonts (the distance from the top of the ascender to the bottom of the descender) is normally expressed in points.
POINT OF PRESENCE (acronym "POP") A computer on the Internet which you can dial up from your home computer using a modem or via an ADSL connection. Once connected, your computer is temporarily connected to the Net, and you can send email and download files or use the World Wide Web.
POINT TO POINT PROTOCOL (acronym "PPP") A data transmission standard that enables a computer to use TCP/IP over a normal telephone line.
POINT TO POINT PROTOCOL ON ATM (acronym "PPPoA") A network protocol for encapsulating PPP frames in Asynchronous Transfer Mode AAL5. It is used mainly with cable modems, DSL and ADSL services. It offers standard PPP features such as authentication, encryption, and compression. If it is used as the connection encapsulation method on a ATM based network it can reduce overhead slightly (around 0.58%) in comparison to PPPoE, it also supports (as does PPPoE) the encapsulation types: VC-MUX and LLC based. This is the protocol used for most ADSL connections in New Zealand.
POINT TO POINT PROTOCOL ON ETHERNET (acronym "PPPoE") A network protocol for encapsulating PPP frames in Ethernet frames. It is used mainly with cable modems and DSL services. It offers standard PPP features such as authentication, encryption, and compression. In essence, it is a tunnel protocol which allows one to layer IP over a connection between two Ethernet ports, but with the software features of a PPP, so it is used to virtually "dial" to another Ethernet machine and make a "serial" connection with it, which is then used to transport IP packets, based on the features of PPP.
POINTER A small shape that appears on the screen and moves as you move the mouse. You use the pointer to select icons and gadgets and to choose menu items. The look of this pointer can be altered by selecting the "Pointer" option displayed on the Preferences screen or window.
POLYPHONIC Literally means "many sounds" and is the ability of any musical device to play more than one note at a time, using the same instrument from data on a single MIDI channel.
POP (pronounced "pop") Acronym for Point Of Presence.
PORT An socketed outlet on the computer which allows for communication between the computer and any external devices. For example, the serial port is a 25-pin socket, which allows devices such as modems, digitisers, samplers, printers, etc, to be connected.
PORTABLE DOCUMENT FORMAT (acronym "PDF") A file format developed by Adobe Systems, and generally associated Adobe Acrobat. PDF captures formatting information from a variety of desktop publishing applications, making it possible to send formatted documents and have them appear on the recipient's monitor or printer as they were intended. To view a file in PDF format, you need Adobe Acrobat Reader (a free application distributed by Adobe Systems for PC's and Mac's), or a PDF viewer for Linux and Amiga OS systems. While many PDF files were initially created using only Adobe Acrobat, a wide range of shareware and freeware programs are now available for creating PDF files.
PORTABLE NETWORK GRAPHICS (acronym "PNG") A file format for graphics images that was designed as a replacement and extension to GIF and LZW-based TIFF, after Unisys Corporation started demanding royalties on GIF/LZW code. It quickly gained general recognition as the best lossless format for storing digital images and in time may replace both GIF and TIFF, especially since it can handle colour up to 48 bits, but it has only gained limited popularity. In a palette-based environment, true colour images are dithered using a fast Floyd-Steinberg method.
PORTRAIT MODE Outputting pages in vertical orientation as opposed to Landscape mode.
POSTSCRIPT FONTS Also known as Adobe Postscript fonts, these fonts are based on the device independent standard for fonts, developed by Adobe Systems, which means that any font will print identically on any Postscript compatible printer whatever its manufacturer. What's more because Postscript fonts are based on vectors rather than bitmaps, they can be scaled to any proportion without loss of quality. The standard font set was originally 13 typefaces, consisting of 3 font families, each with four faces, plus a symbol font set consisting of the Greek alphabet, and a variety of mathematical and typographical symbols. Of the 3 font families, Times Roman and Helvetica are proportional fonts, while Courier is fixed pitch, and the typefaces are regular, italic, bold and bold-italic. Most PostScript printers come with additional builtin font sets (many have 35 variations on 9 different font families) and the number of fonts is growing all the time, with many being available in Public Domain. However, you need to take care because there are essentially two types of Adobe fonts, called Type 1 and Type 3. Type 1 fonts are outline fonts which employ a technique called "hinting", in which the letterforms change slightly as the font changes in size, to compensate for differences in our perception of different sizes, and this actually creates an illusion of identical letterforms. Type 3 fonts are non-hinted outline fonts and, unlike Type 1 fonts, they can have complex composite characters, percentage fills and strokes. They take longer to print, use more printer memory, and cannot be displayed on screen. These differences are really only noticeable on the higher-resolution printers.
POWER SUPPLY UNIT Generally refers to the external power supply supplied with each keyboard type machine, such as the A500, A600, A1200 etc. Because of its shape and its weight it is commonly referred to as "the brick".
POWERPACKED A description given to files that have been compressed using PowerPacker. These files often have a suffix of .PP as part of the name.
POWERPACKER A popular compression program thyat appended a special header to the files when they were compressed, so that it could automatically de-compresses them when run.
PPP (pronounced "P-P-P") Acronym for Point to Point Protocol.
PPPoA (pronounced "P-P-P-oh-A") Acronym for Point to Point Protocol on ATM.
PPPoE (pronounced "P-P-P-oh-E") Acronym for Point to Point Protocol on Ethernet.
PRE-EMPTIVE MULTI-TASKING A form of multi-tasking where each task is allocated a relative priority, and tasks with a lower priority will relinquish control to any tasks with a higher priority. Once a task has finished what it wants to do, the next highest task gets control and so on. The advantage of this method is that better use is made of the CPU, and where one task may have to wait for some resource such as data from a file, it can be running another task while it is waiting. This is the method used by the AmigaDOS operating system. For instance, if you have several windows open at once, then all of the tasks associated with those windows can, in effect, continue processing according to their priorities. There is also another benefit using AmigaDOS, in that ARexx can be used to send messages or instructions between tasks to perform all kinds of functions, and then return data to the sending task.
PREFERENCES A collection of editing programs which enable the look and feel of an Amiga to be customised to suit the user, and saved for future use.
PRINTER DRIVER A special piece of software that allows the Operating System on a computer communicate with any printer. It acts as an interpreter to convert the computer's commands into commands that a particular printer understands. Each printer requires its own printer driver - using the wrong driver gives unpredictable results.
PRODUCTIVITY MODE The special non-interlaced high resolution display mode that was available on the Amiga under Workbench 2 and above, which was similar to VGA mode on MS-DOS machines.
PROFESSIONAL FILE SYSTEM (abbreviation "PFS" A replacement filesystem for the Fast File System on the Classic Amiga. PFS claimed improved performance, reliability and stability than FFS, and could handle hard disks up to 2000GB and partitions up to 104GB.
PROGRAM A series of instructions that tells the computer to perform specific tasks, such as those required for word processing, graphics, games, etc, and is referred to as "software".
PROGRAMME A list of events and performers which you might purchase when you go to a concert or sports game.
PROJECTS Any files created by programs/tools, such as a Notepad document.
PROTOCOL An agreed communications standard, whereby computers can exchange information either directly or indirectly. Common direct protocols are XModem and ZModem, while the most common indirect protocol used by ther Internet is PPP.
PS/2 PORT A type of port used on most modern computers to connect the keyboard and mouse devices. While the connectors on older machines will be black, the keyboard port has been coloured bright purple and the mouse port bright green on more recent machines for easier identification.
PSU Acronym for Power Supply Unit.
PUBLIC DOMAIN Public Domain is the general heading applied to software or data that is freely distributable. In fact under this heading there are three distinct groupings - Freeware, Shareware and Licenseware. Programs and data which are sold commercially are NOT Public Domain, and are therefore subject to normal copyright laws. This does not mean that Public Domain programs are not good enough to be commercially sold, it is more likely that the author prefers to make it freely distributable rather than sell it, because it then has the potential to reach a large user base for very little cost and in most cases the shareware fees can be kept quite modest. There are many amazing programs in the Public Domain some too small to sell but extremely useful none-the-less, and it is often a good way to learn more about your Amiga because the authors frequently provide practical information as well.
PULL DOWN MENUS The list of selectable functions and operations that appear at the top of the screen on an Amiga when the right mouse button is held down. Moving the cursor over the menu(s) will cause items to become highlighted and/or additional menus may appear.
PUZZLE AND QUIZ GAMES A style of game where the aim is to analyse situations and solve puzzles in order to progress through the game often competing against one or more other players or simply the computer. For example, Lemmings, Diggers, One Step Beyond, Tetris, Goblins etc.

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