The purpose of a glossary in a book is sometimes partly as a way of listing some of the basic concepts covered in the book. That is not me intention here. This glossary has been done on the basis that someone may read a word or technical term or abbreviation used in Archive magazine and think, "What does XXXX mean?". If you think that, look up the word in this glossary and it does not appear, please ring, write or fax and tell us what you would like us to add.
Paul Beverley 21/5/94
!
! -- (pronounced "pling") A term used to denote an exclamation mark!
A
ADFS -- (Advanced Disc Filing System) This is the proprietary system used by Acorn for organising and storing data on floppy and hard drives.
AIM -- (Another Image Manager) A suite of image processing software produced by Delft University of Technology in the Netherlands.
Application -- The more general use of this word means any job for which the computer may be used, but it has a has a more specific definition. It is used to refer to a directory (with a name beginning with a "!") which contains a program or programs that work under RISC OS to perform a particular function. When the application is loaded, it usually makes itself available to the user via an icon on the righthand side of the iconbar.
Application directory -- Similar to an ordinary directory in that it contains other files and directories but its name starts with an exclamation mark so that when you double click on the directory, it starts up the application rather than just opening the directory. To open an application directory, double click with <shift> held down.
Apps icon -- This is an icon that appears on the lefthand side of the iconbar (RISC OS 3 onwards). It gives you access to a range of applications such as Draw, Paint, etc that are provided with each Archimedes or Risc PC computer.
ARM -- (Acorn RISC Machine) This is the original name for the 32-bit RISC processor designed by Acorn Computers Ltd. In the name "ARM Ltd", the company formed between Acorn and Apple, the "ARM" actually stands for Advanced RISC Machine.
ASCII -- (American Standard Code for Information Interchange) This is the most commonly used code for representing text using 8-bit binary numbers.
ASIC -- (Application Specific Integrated Circuit) A single chip electronic circuit that is specially designed (by computer simulation -- what else?!) for a particular application, e.g. to provide the logic needed to interface a ’486 processor on a Risc PC second processor card to the main ARM600 processor and its address and data buses.
Assembler -- A compiler for converting a program written in mnemonics into a machine code executable program.
AUN -- (Acorn Universal Networking) This does not apply to a specific product or even a network user interface but "the overall banner for Acorn’s networking policy for the ’90s giving the strategic direction of networking for Acorn computers."
B
Backdrop -- This is a desktop background which may be a sprite or just a pattern.
Backplane -- A small printed circuit board with connectors on it that allows you to plug in a number of expansion cards.
Basic -- (Beginners All-purpose Symbol Instruction Code) A commonly-used interpreted high level language. It comes as standard on all Acorn computers.
Baud -- This is a unit of speed for serial data transmission. 1 Baud = 1 bit per second.
BBS -- (Bulletin Board Service) A bulletin board is an application run on a computer which stores information and messages that can be accessed by other computers, usually via the telephone line using a modem. Many bulletin boards allow a number of other computers to connect to the host computer at the same time by using a number of different modems and phone lines.
BIOS -- ??????
Bit -- A bit is the smallest unit of binary data. It has two values, 0 and 1. A group of 8 bits of data (referred to as a byte) could be used to represent a single character using, most commonly, the ASCII code or it could represent (part of) an instruction that the computer would execute at some stage or it could represent (part of) a number.
Bit-mapped (graphics) -- It is possible to represent a picture on a computer by using a matrix of (coloured) dots. The resolution of bit-mapped pictures is limited by the numbers of dots used. (This contrasts with vector graphics -- see below. For example, the Paint application produces bit-mapped graphics whereas Draw produces vector graphics.)
Bpp -- (Bits per pixels) The number of binary bits used to store the colour of each pixel.
Bubblejet printer -- This is a type of inkjet printer where the patterns on the paper are generated by squirting ink through a series of tiny nozzles in the print head. Functionally, it is the same as an inkjet printer.
Bullet -- A large black dot -- • -- used to highlight something within some text.
Bus -- A set of parallel wires or PCB tracks along which data is transmitted in a computer system. The width of the bus
Byte -- A byte refers to (usually) 8 bits of binary data stored within a computer’s memory or on a data storage medium.
C
C -- A high level compiled language.
C++ -- This is an object-oriented version of the C language.
CAD -- (Computer Aided Design) A computer-based application that allows users to draw, design and model engineering objects.
Caps -- Short for 'capitals'. See also small caps.
Capslock key -- This is a key on the lefthand side of the keyboard. When it is pressed and the Capslock light comes on, all text typed into the keyboard appears in upper case.
Caret -- A vertical bar in a screen display that marks the point at which text will appear if it is typed in from the keyboard.
CD -- (Compact Disc) A high density digital storage medium originally intended for hi-fi sound reproduction but now applied to storage of text and image data for various computer applications.
CDFS -- Filing system used for accessing CD-ROMs.
CD-ROM -- (Compact Disc Read Only Memory) A CD used for the storage of computer data. It is called a ROM to emphasise that the data on the disc, once written in the manufacturing stage, cannot be modified.
CFS -- (Compression Filing System) This is a way of accessing a data storage system through a compression/decompression system such that it is transparent to the user, i.e. the user need hardly know that the data is being compressed and decompressed but just sees it as being read from and written to the storage device.
Clear (files) -- A standard format for storing and transferring 24-bit pictures.
Colour depth -- Every pixel on a computer screen display has its colour defined by a certain number of bits of data. The colour depth refers to the range of different colours available for each pixel in a particular screen mode. If a single bit were used, it would only allow it to be one of two colours -- usually black or white. If it were defined by two bits, it could have 4 (22) different colours, four bits would provide (24) 16 different colours, 8-bit provides 256 (28) colours, 16-bit gives over 32 thousand colours and 24-bit allows each pixel to have any of about 16.7 million different colours -- about as much as the human eye can distinguish. The 32-bit colour of the Risc PC "only" gives 16 million colours but the extra 8 bits can be used by the computer to produce various different special effects.
Command line -- All Acorn computers now come with a WIMP interface. However, it is possible to give the computer commands by typing them in from the keyboard. If you press <f12>, an star prompt appears. This is the command line. You can enter commands such as CAT<return> to get a catalogue of the current storage device.
Compiler -- In a computer language, instructions that the programmer enters as (vaguely) understandable words have to be translated into series of the very simplest steps that the cpu executes. These simple instructions are called machine code. The job of a compilers is to take the whole of a program and convert it into a single machine code program which can be executed then or at a later stage. This contrasts with an interpreted language in which each individual line of the program is converted into machine code as the program is running. In a compiled language, you have to convert the whole program before you can run any of it whereas in an interpreted language you can run the program at any time, stop it, change the program and run it again. On the other hand, interpreted programs tend to run more slowly because even if one line of the program is run many times, it has to be interpreted into machine code every time it is run.
Compression/decompression -- There are various mathematical techniques which can be used to store computer data in a smaller amount of memory than the uncompressed data occupies. Some of these techniques are completely reversible so that the decompressed data is identical to the original data. However, in the case of images, it may be acceptable to allow a degree of degradation of the data in order to increase the amount by which the data is compressed.
Configuration -- A collection of settings and option which describe how the computer will operate when it is first switched on.
CPU -- (Central Processing Unit) This is the electronic circuitry at the heart of a computer that executes (very rapidly!) a series of simple steps of reading, manipulating and writing information to and from the computer's RAM memory and input/output devices.
Crop marks -- In publishing, it is important to define where a printed image appears in relation to the edges of the paper. To do so, the images can be printed on a larger sheet of paper and markers placed on the sheet to show where the corners of the paper will be.
CSV -- (Comma Separated Variables) A standard way in which data is stored in a file where the items of data are separated by commas.
CYMK -- (Cyan, Yellow, Magenta, Key) A method of specifying colour by using the amounts of the three primary (subtractive) colours plus the amount of black (Key).
D
Database -- The definition of this word has changed over the years. It used to mean a unified collection of data files but now it tends to refer to an integrated system of data plus the means of interrogating and manipulating the data -- even to the extent of referring to a database language.
Daughterboard -- See under 'motherboard'.
DEBI -- (DMA Extended Bus Interface) This is a means of connecting expansion cards to the Risc PC. (Depending on which magazine you believe, it can support anything between 8 and 14 expansion cards! -- I suspect it's 8 but I will check.)
Debug -- Remove the bugs (errors) within a program.
Debugger -- An application written to provide provide tools to aid the process of finding errors in a program.
Decompression -- See compression/decompression.
Default -- The standard setting or option which the computer selects unless the user has specifically told it to do otherwise.
Device -- This is the technical term for any information storage medium (e.g. floppy or hard drive) or transmission system (e.g. network, modem or printer) that can be accessed through the computer. Each currently available device is represented by an icon at the lefthand side of the iconbar.
Dhrystones -- (strictly Dhrystones/second) This is a means of indicating the speed of a processor by testing the number of iterations it can perform of a particular test program each second. For example, the Risc PC 600 with a 30MHz ARM600 processor can perform about 40,000 Dhrystones/second.
Dialogue box -- A window in which you are expected to select various options and/or enter a filename before the computer performs a particular task or operation.
Digitiser -- An electronic circuit which takes an analogue signal such as a sound of a video signal and turns it into digital information which can be stored and/or manipulated within the computer and output again as a sound or video signal.
Direct drive laser printer -- In conventional laser printers, the computer sends information to the printer about what is to be printed, in what position and with what styles etc. The processor and memory in the laser printer are then used to work out what dots to place where on the paper. In a direct drive laser, by contrast, the computer works out what the pattern of dots should be and then sends the dot pattern down to the printer on a high speed ("video") parallel interface. This means that the printer need little or no memory of its own and the process is faster because ARM processors tend to be much more powerful than the processors used in laser printers.
Directory -- When data is stored on a storage medium such as a floppy disc, it can be grouped into directories. When the iconbar icon is clicked, a window appears showing the data in the root (i.e. main) directory. This may be items of data (stored as files), applications or other directories. These directories in turn can contain more information and/or further sub-directories. This system of directories within directories is called a hierarchical data structure.
Dithering -- When displaying a picture on a computer screen in, say, a 256 colour mode, it is possible to give the impression of intermediate colours by mixing dots of the different colours in different ratios. This is done using a random displacement of these dots to avoid a patterned effect. This technique is called dithering.
DMA -- (Direct Memory Access) When information is being taken into a computer from an external source, the cpu normally reads a location, or block of locations, in the external device and writes the information into its own RAM memory. With DMA, by contrast, the information is written directly from the external device into the cpu's memory without the cpu being involved. This means that the process is much faster as the cpu can be doing other things while the information is being loaded automatically into memory.
Dongle -- This is a small electronic circuit usually held in a plastic connector block that goes on the parallel port of a computer. It forms an electronic 'key' that allows you to use a particular application (such as Impression or ArtWorks). The application checks every now and then to see if a dongle is present and, if not, it shuts itself down and will not restart.
DOS -- (Disc Operating System -- but also now used as shorthand for DR-DOS or MS-DOS) These are the operating systems most commonly used on IBM PC computers and compatibles. They can be used on Acorn computers by using the PC Emulator or a PC expansion card or, on a Risc PC, a PC processor card. They are command-line operating systems, i.e. they do not use a wimp interface.
Double density floppy discs -- Discs that can store approximately 800Kb of data when formatted.
dpi -- (dots per inch) On a desktop printer, the text and graphics are reproduced by rows and rows of tiny dots. The smaller the dots, the better the definition of the resulting printout. This is usually specified as the number of dots per inch that the printer can lay onto the paper. The same idea is used for scanning. When scanning a picture or diagram, the grey level (see below) of rows of tiny areas of the picture are assessed by the scanner. The closeness of the areas being differentiated is measured in dots per inch.
DPMS -- (Display Power Management Signalling) When monitors are not being used, it is a waste of energy to have them on at normal brightness. RISC OS 3 supports screen blanking which helps to reduce energy consumption, but some monitors can accept special electronic signals from a computer to tell it to drop into a very low power consumption mode if it is not being used. This signalling between computer and monitor is not available in all monitors although a lot of newer monitors are beginning to provide it.
DPOB -- (Dual Processor Open Bus) On the Risc PC, the processor(s) are held on separate cards which plug into the main PCB or motherboard. It can take two such processor cards and the dual processor open bus is a way of allowing two different (or similar) processors to share the use of the computer's memory and input/output and data storage facilities.
DRAM -- (Dynamic Random Access Memory) This is the most common form of RAM memory used in computers today. 'Dynamic' is a technical term which refers to the way in which the information is stored within the chips.
DSP -- (Digital Sound Processing)
DTP -- (DeskTop Publishing) As desktop computers have increased in processing power, it has become possible for them to handle both text and graphics, to allow users to manipulate them on-screen and output them to a printer. In this way, "books" can be produced on a desktop computer -- hence the term 'desktop publishing'.
E
Econet -- This is a means of connecting two or more computers together so that they can exchange information and share the use of peripherals such as printers. It is a type of Local Area Network (LAN) developed in the early '80s by Acorn Computers Ltd.
EEPROM -- (Electrically Erasable Programmable Read-Only Memory) A form of non-volatile memory that remains unchanged even when the power is switched off but which can be altered in situ by using appropriate electronic circuitry i.e. it can be reprogrammed through software.
E-mail -- (Electronic mail) A means communicating with other computer users via a LAN or through a modem to a national or international computer centre.
EPROM -- (Erasable Programmable Read-Only Memory) A form of non-volatile memory that remains unchanged even when the power is switched off but which can be altered by using ultraviolet radiation to erase the information and high voltages to re-program it. (But see Flash ROM and EEPROM.)
EPS -- (Encapsulated PostScript) This is a type of computer-generated file containing the necessary PostScript commands to reproduce the picture. It usually includes a 'snapshot' of the picture that can be used for positioning purposes. EPS is a defined standard allowing output from one application to be used within another.
Ethernet -- Another type of LAN, but much faster than Econet. It was developed by Xerox Corporation in the late '80s.
Expansion card -- (formerly called podules or peripheral modules) An extra circuit board fitted to your computer that will allow it to perform various extra functions which cannot be done with software alone.
F
FAST -- Federation Against Software Theft
File -- A collection of information gathered together and given a filename to identify it. It is stored in a directory in a filing system.
Filer or Filing system -- A system used to handle the storage of information. The ADFS filer and the SCSI filer are the two most common on Acorn machines.
Firmware -- This refers to software, applications and/or data which is stored in a ROM.
Flash ROM -- To change the contents of a conventional EPROM, the chip has to be removed and erased using ultra-violet radiation. It can then be electrically re-programmed. A flash ROM, by contrast, can be re-programmed electrically in situ, i.e. it can be reprogrammed through software.
Floating point numbers -- In order to represent a wider range of numbers than can be done with integers, and to represent fractions, computers use floating point numbers. These use a number of bytes (usually four) to represent the main part of the number and another byte to represent the power of two by which the number is multiplied.
Floppy disc/drive -- This is a data storage medium consisting of a removable flexible (floppy) magnetic disc in a hard plastic case. These discs can be inserted as required into a floppy drive usually housed within the case of the computer.
FMV -- (Full Motion Video) A term used to refer to displaying video on a computer screen at full speed. Acorn Replay provides FMV at 12.5 or 25 frames per second.
Fonts -- Characters on the screen and on the printed page can take on all sorts of different shapes and styles. A font is a set of characters that have been designed so that all the letters of the alphabet and a whole range of other special characters (200 or more in a complete set) have the same style. There are also sets of related fonts using the same basic style but with the characters angled (italic) or made heavier (bold) or both (bold italic).
Format -- Formatting is preparing a floppy disc or hard disc ready to receive data. Hard discs usually arrive ready-formatted. Floppy discs may be formatted in a number of different ways. Not all formats of floppy disc can be read on all computers. Without any extra software, Acorn computers can read and write various Acorn formats as well as a number of different PC and Atari formats. With extra software, other formats, such as Apple Mac, are also accessible on Acorn computers.
FPA -- (Floating Point Accelerator) This is a hardware add-on to a cpu which enables it to do floating point calculations more quickly.
FPE -- (Floating Point Emulator) If an application requires full floating point calculations, it is possible to run it on a computer that doesn't actually have an FPA by emulating the FPA's functions in software.
Function keys -- These are the set of twelve keys at the top of the keyboard. What they do will depend on the application currently in use.
G
Gb -- (Gigabyte) Approximately one thousand million bytes of computer data. (Actually, it is 1K × 1K × 1Kb = 230 = 1024 × 1024 × 1024 = 1,073,741,824 bytes.)
Genlock -- This is a device which enables the output from the computer's video system to synchronised with a normal video signal so that computer-generated text and graphics can be superimposed on the video signal.
GIF (files) -- (Graphics Interchange Format) A standard format for storing and transferring bit-mapped graphics.
Grey levels -- A photograph may have some areas completely white and some completely black. Most areas, however, will be somewhere in between. If you wish to represent that picture electronically, you have to judge the 'greyness' of each part of the picture. If you represent this on a scale of 0 to 15 (16 grey levels), it will not give such a faithful representation of the picture as if 64 or 256 grey levels were used. However, the more grey levels used to represent each point on the picture, the more data is being used. For example, in 256 grey levels, a full A4 picture scanned at 400 d.p.i. could occupy as much as 12Mb!
GUI -- (Graphical User Interface) At one time, virtually all interaction between humans and computers was done on the basis of the human typing words or codes into some form of keyboard. As computing power became more accessible, it became possible to provide a form of interaction that was based far more on pictures (icons) within windows on the screen. The user could then indicate choice and initiate action by using a mouse or trackerball to move a pointer around the screen.
H
Hard drive -- A case containing a number of rigid metal discs covered with magnetised material that can be used to store data; it usually has a capacity of several megabytes or even gigabytes.
Hierarchical -- This is usually used in referring to the data structure on storage media -- see 'directory'.
High level language -- This refers to a computer language in which instructions that the programmer enters are each converted into a number of machine code instructions by a compiler or an interpreter. Basic, Fortran, C etc are high level languages whereas assembly language is a low level language.
High density floppy discs -- Discs that can store approximately 1,600Kb of data when formatted under ADFS or up to 1,440Kb when formatted under MSDOS.
HSV -- (Hue Saturation Value) This is a colour-picking system for use in DTP.
I
Iconbar -- The strip along the bottom of the computer screen that contains icons for devices (to the left) and applications (to the right) that are currently available to the user.
Icons -- Small pictures representing devices, files, directories, applications, etc.
IDC -- (Insulation Displacement Connector) This refers to a connector where the connection between the contacts and the individual wires is made by squeezing a row (or usually two rows) of sharp metal teeth onto a ribbon cable so that the teeth cut into the insulation and make contact with each individual wire.
IDE -- (Integrated Drive Electronics) An electronic standard method of connecting one or two hard drives to a computer system. The standard was set up to provide a simpler and cheaper means of connecting hard drives to IBM and compatible computers than was currently available.
Image processing -- If an image is stored on a computer as binary data (such as a sprite file) it is possible to manipulate the data mathematically to enhance, distort, translate or otherwise modify the picture in controlled ways.
Inkjet printer -- This is a type of printer where the patterns on the paper are generated by squirting ink through a series of tiny nozzles in the print head.
Input focus -- The output from the keyboard can be directed to one and only one window at a time. The window currently receiving information from the keyboard is said to have the input focus. This is indicated by the title bar of the window changing from grey to yellow.
Interlace -- Build up a picture on a monitor screen using two passes, each displaying alternate lines, the aim being to reduce flicker effects.
Interpreter -- A type of high level language in which each instruction is converted into machine executable code line by line, as the program proceeds. (See 'compiler' for more explanation.)
I/O -- (Input/Output)
IOC -- (Input/Output Controller) The I/O chip used on pre-Risc PC Acorn computers was called IOC.
IOMD -- (Input Output Memory Device) This is a computer chip designed by ARM Ltd which allows ARM processors to control input/output devices and to access memory.
J
JPEG -- ("Joint Picture Encoding Group" or, some say, "Joint Photographic Experts Group") It is a body set up in the USA to produce an industry standard for still picture compression and storage. The theory is that, with an agreed file format, one company's decompression program can read the files produced by someone else's compression program.
K
Kb -- (Kilobyte) Approximately one thousand bytes of computer data. (Actually, it is 210 = 1024 bytes.)
Kerning -- This refers to the spacing between individual pairs of characters. To improve the look of printed text, certain character pairs need to be printed closer together than others.
L
LAN -- (Local area network) A general term for a means of connecting computers together on one site so that they can share information. Econet and Ethernet are examples of LANs.
Letter box mode -- There are some monitors that were never designed to display screen modes of the like of Acorn modes 12, 15, etc. Some are completely incapable of displaying them whereas others can display them but with a somewhat reduced vertical height, the shape being likened to the mouth of a letter box.
Linker -- When using a compiler, this is the program that joins the object code from various sub-programs, including the library routines, to form the final executable machine code program.
Lisp -- A high level computer language often associated with artificial intelligence programming.
Low level language -- A language which involves programming the computer at the level of one written instruction (or mnemonic) for each machine code instruction.
M
Mb -- (Megabyte) Approximately one million bytes of computer data. (Actually, it is 1K × 1Kb = 220 = 1024 × 1024 = 1,048,576 bytes.)
MEMC -- (MEMory Controller) The chip used on pre-Risc PC Acorn computers to control the way the cpu and video controller accessed the computer's memory.
MHz -- (MegaHertz or Millions of cycles per second) This is most often used to refer to the speed of a computer's processor or memory. e.g. the Risc PC 600 has a 30MHz processor which means that it can carry out 30 million program steps each second.
Midi -- (Musical Instrument Digital Interface) A defined standard for the physical link-up between musical instruments and controllers, and also the format of the data transmitted.
MIPS -- (Million Instructions Per Second) A measure of how fast a cpu is running in terms of the number of instructions it can execute each second.
Mnemonic -- A code used in an assembler to represent a machine code instruction.
Mode -- See screen mode.
Modem -- (An abbreviation for modulator-demodulator) It is a device which takes a serial stream of computer data and converts it into audible tones that can be transmitted down a telephone line that was originally design for carrying voice information. It enables two computers to exchange data at a distance via the telephone system.
Monitortype -- A computer variable that determines which ranges of screen modes the computer will attempt to display on your monitor.
Motherboard -- The main circuit board of a computer is sometimes referred to as a motherboard, especially when, as in the Risc PC, many of the functional parts of the computer are on separate PCBs (sometimes called daughterboards) that are plugged into the main or motherboard.
MPEG -- (Motion Picture Experts Group) A group of technologists who are establishing an international standard for the compression of moving video and its associated audio.
MTBF -- (Mean Time Between Failure) An indication of how long, on average, it will be before a machine goes wrong.
Multimedia -- A blend of communications elements, usually computer-based, which allow information in such forms as sound, speech, text, still pictures, moving images and animations to be presented to the user so that it can be accessed in an interactive way, the user selecting which piece(s) of information to pursue.
Multisession -- Information stored on a PhotoCD can be added to at a later date with the appropriate (very expensive) equipment. In order to read all the information on these CDs, you need a CD-ROM drive that is multisession capable.
Multisync monitor -- Some monitors are designed (for cheapness) that only display only certain display modes. Others can display a range of different modes -- they can synchronise onto a range of different frequency signals and are therefore called 'multisync' monitors.
Multitasking -- An operating system like RISC OS is capable of running a number of different tasks all at the same time. This is multitasking.
N
Network -- A means of connecting a number of computers together so that they can share data and the use of peripherals.
O
Object code -- the machine-executable code produced by a compiler.
Object oriented -- Any offers?!
OCR -- (Optical Character Recognition) Computers can be trained to examine the shapes of typed or printed characters and work out what the letters, words and sentences are. So, combined with a scanner or camera and digitiser, the computer can 'read' text off books and paper. Because of the difficulty of being 100% accurate, it may take as long to edit out the mistakes than to type the text in from scratch so OCR programmers are fighting all the time to make their programs more and more accurate without becoming too slow for practical use. This facility will become more viable as we get progressively faster processors.
OLE -- (Object Linking and Embedding) This is a means of linking data of different types (e.g. text, drawfiles, sprites, etc) within one document so that each element can be easily edited. Double-clicking on an element brings up the appropriate editing application (Draw, Paint, ArtWorks, etc) to allow you to make the necessary changes without having to export and then re-import the data.
Operating system -- This is the set of "house-keeping" programs within a computer which handle all the input/output, filing systems, etc. All modern Acorn computers come with the RISC OS operating system as standard (stored in ROM) but it is possible to use alternative operating systems such as DR-DOS and MS-DOS by adding the appropriate software or hardware.
Option icon -- An icon that appears in a dialogue box. Each time you click on it, you will switch a particular option on or off.
OS -- (Operating System)
Outline fonts -- These are fonts that are described mathematically by using equations to define the curves that make up the outline of the character's shape. Using these equations, it is relatively simple to work out how to display any font at any size, either on the screen or on a printer where the shape has to be reproduced as a series of dots.
P
Palette -- This is a set of colours used for the desktop display. If the display has, say, 256 colours, the palette determines which actual physical colour is displayed on the screen for each of the colour numbers from 0 to 255.
Parallel -- A device or communication channel is said to be parallel if the data is sent several bits at a time down several parallel wires -- the printer port sends eight bits of data at a time.
Parallel processor -- In some computers, such as the Risc PC, it is possible to have two processors working side-by-side sharing the use of memory, data storage and peripherals -- such processors are referred to as 'parallel processors'.
Parent directory -- The directory within which the directory you are currently dealing with is stored. (It is the opposite of a subdirectory.)
Pathname -- This is the full name of a file or directory including the filing system, disc name (or number) and the sequence of directories that have to be opened to access that particular file or directory.
PBM (files) -- (Portable Bit-Maps) A standard format for storing and transferring bit-mapped graphics.
PCB -- (Printed Circuit Board) A piece of insulating material covered with conducting tracks used to interconnect electronic components to make up an electronic circuit.
PC Card -- A PC processor on a separate card that can be used as a second processor in a Risc PC.
PC ISA Bus -- ???????????????
PC Emulator -- A software application that can work within RISC OS or as a separate program taking over the whole of the computer's processing power which enables the computer to pretend to be an IBM PC and run (most of) the programs that are written to run under MS-DOS or DR-DOS on those computers.
PC Expansion Card -- An expansion card containing a PC processor plus memory plus some I/O capability that can allow PC programs to be run within the RISC OS environment.
Pentium -- This is a 32-bit cpu with a 64-bit data bus produced
Peripheral -- An item of hardware such as a monitor or printer that can be connected to your computer.
Pinboard -- This is an application that makes use of the blank areas of the desktop. You can 'stick' various files or applications onto it so that they are easily accessible without having the filer windows open for each of the directories in which they are stored.
Pixel -- A tiny point of light and colour which is the smallest picture element in a video or computer image. The more pixels making up the image, the better the resolution.
Podule -- See 'expansion card'.
PostScript -- A page description language used in some laser printers and imagesetters. PostScript is a defined standard so that applications using it can produce output that can be printed on any PostScript device.
Printer driver -- This is the program that converts a document or file created by an application into information that your particular printer needs to reproduce the information on paper. The term can be extended to "printing" a file or document via a fax modem. The output is in the form which a fax modem can then transmit, the printed output appearing on the fax at the other end of the phone line.
Printer manager -- An application that oversees the printing process.
Prolog -- A high level computer language often associated with artificial intelligence programming.
Processor -- See CPU.
PRM -- (Programmers Reference Manual) A set of manuals covering many highly technical programming details of the RISC OS operating system.
Public Domain (PD) -- There are a number of enthusiastic people who produce programs and clipart which they want to make freely available for other people to use -- rather than trying to make money by selling them. The material is distributed at cost by various individuals and agencies. There are quite a number of PD libraries dealing with material for Acorn computers. (Norwich Computer Services runs one such library, part of which raises money for charity.)
Q
Quit -- Close a file or application so that its window(s) disappear from the screen and, in the case of an application, it disappears from the iconbar.
R
Radio icons -- A group of buttons within a dialogue box, only one of which can be selected at a time.
RAM -- (Random Access Memory) This is the place within the computer where information is stored on a temporary basis. When the computer is switched off, information in RAM is lost.
RAM disc -- Part of the computer's RAM memory can be set aside so that the user can store files and data on a temporary basis during a computer session. The information is accessed through a filer in the same way that you would access an external storage medium such as a floppy or hard drive.
Relocatable module -- A section of computer code that can be used to extend the facilities of the operating system and which can then be used by any application running in the computer.
Removable hard disc drive -- This is cross between a hard drive and a floppy drive. It uses a solid metal disc so that it can store large amounts of data (currently up to 270Mb on a single disc) but the disc is held in a plastic case like a thick floppy disc and it can be taken in and out of the drive so that a number of discs can be used for different purposes, and the data can be transferred easily from one computer to another.
Resolution -- The complexity of detail that can be seen on a computer screen or a printer can be specified in terms of resolution, i.e. the numbers of dots per inch.
Resources -- The various programs and data files which an application uses to perform its task.
RGB -- (Red Green Blue) Any colour can be made up of a combination of different amounts of light of these three primary colours. So colour monitors (RGB monitors) use sets of thre coloured phosphor dots of these three colours.
RIP -- (Raster Image Processor) This is a device used in the printing industry to produce a high resolution something-or-other... (Any offers of a definition?)
RISC -- This is an acronym for Reduced Instruction Set Computer. Companies like Acorn realised that the trend to more and more complex computer processors wasn't necessarily the best way to increase the overall speed of computer processing. These complex processors were spending the majority of their time doing simple tasks anyway. What Acorn did was to make the processors simpler, which meant they could work much faster doing the simple jobs like pushing text around and drawing dots on the screen. This is partly why RISC processors are so well-suited to DTP applications -- though the explanation is grossly over-simplified!
RISC OS -- This is the operating system used on Acorn's RISC-based computers.
RMA -- (Relocatable Module Area) The area of RAM set aside for the program modules used by different applications.
ROM -- (Read-Only Memory) A form of non-volatile memory that remains unchanged even when the power is switched off and which cannot (usually) be altered. (But see Flash ROM and EPROM.)
Root directory -- The main directory of a storage device which contains all other directories and files and which is displayed when the iconbar icon of the device is clicked.
RS232/RS423 -- These are two different (but similar) electrical standards for the transmission of serial data.
S
Sampler -- An add-on that takes a sound signal as input and turns it into digital data that can stored and/or manipulated within the computer and then be output again through a DAC (digital to analogue converter).
Scanner -- An add-on that enables the user to read visual images into the computer from originals such as photographs and books.
SCART -- (Syndicat des Constructeurs d'Appariels de Radio et de Television -- well, you wanted to know, didn't you!) A means of connecting computers, video recorders, etc to televisions and monitors using standard connections.
!Scrap -- A special directory on which RISC OS makes available for applications to use as temporary storage space. Use of this directory is under the control of the application and the user is normally unaware of it.
Screen blanking -- Within RISC OS 3 is an optional facility (set in the configuration) which switches the screen to black after a user-definable length of time if the computer is not being used. As soon as a key is pressed or the mouse is moved, the screen returns to normal. This reduces the likelihood of monitors having patterns 'burned in' to the face of the tube (and reduces the power consumption of the monitor to some extent).
Screen mode -- Information can be displayed on TV or monitor screens in a number of different formats. The numbers of pixels that make up the screen may be different (from, say, 480 × 512 to 1600 × 1200 or more) and the colour depth of each pixel may vary. The amount of memory used to display the screen will increase as both the number of pixels and the colour depth are increased. There is a trade-off between the two as the amount of video memory is usually limited. A particular size and colour depth is referred to as a screen mode.
Scrolling -- If a file or document is too large to be displayed on the screen all at once, it is displayed in a window with scroll bars and scroll arrows so that you can move around and view different parts of it as necessary.
SCSI -- (Small Computer Systems Interface) This is an agreed standard system for communicating data between computers and data storage and acquisition devices, the data being transmitted along parallel data paths. It is commonly used to link a computer to hard drives, CD-ROMs and/or scanners, but it can also be used to link computers together subject to the limitation that you can only link a total of eight different 'devices' together.
Second processor -- In computers such as the Risc PC it is possible to have more than one processor working together sharing memory, data storage and peripherals. In the Risc PC, the ARM610 takes charge when the computer is first switched on and it then allows the other processor (the 'second processor') access to memory etc.
Self-test -- When a computer is switched on, it runs through a series of tests to check, as far as it is able, that it is functioning correctly. In a RISC OS 3 (or later) computer, if any of these self-tests fails, it will usually issue some sort of error message. If the system has not managed to get as far as producing a working display on the VDU, it will send a coded message about the likely error by flashing the LED on the floppy drive.
Serial -- A device or communication channel is said to be serial if the data is sent sequentially, one bit at a time, as opposed to being sent several bits at a time down parallel wires.
Shovelware -- This is a derogatory term for software and other data of inferior quality that is used to 'pack out' a CD-ROM and make it up to 600Mb, or whatever, to convince the potential purchaser that the disc is worth buying.
Shutdown -- A menu option on the task manager iconbar menu which 'clears up' the computer prior to switching it off.
SIMM -- (Single In-line Memory Module) An industry standard plug-in memory card as used in the Risc PC, for example.
Slice -- (Single Layer Item of Computer Expansion!) The name applies to a single extra layer of case in a Risc PC. It includes a new backplane with two more slots than previously and four locking pins longer than the ones they replace.
Smalltalk -- A high level computer programming language that allows you to use object-oriented techniques.
SOHO (market) -- (Small Office Home Office) A defined market into which companies try to sell their computer goodies.
Source code -- the name given to the program written in a high level language which is converted by a compiler into machine executable code.
Sprite -- A graphic made up of coloured pixels. These can be
SQL -- (Structured Query Language) Language for extracting information from a database.
Subdirectory -- Within any directory, you can store files and other directories. A directory that appears inside another directory is referred to as a subdirectory.
SVGA -- (Super VGA) An enhanced colour graphics standard from the PC world -- 1024×768.
System application (!System) -- An application that contains many of the resources that can be used by any or all other applications.
System disc -- A floppy disc containing a copy of !System.
T
Tapestreamer -- Computer data has, for many years, been stored on magnetic tape. This is a basically inefficient method in the sense that if you are at one end of the tape and the data you want is at the other end, it can take a long time to reach the information. However, it is very efficient in the sense that the medium, magnetic tape, can be very inexpensive per megabyte. A tapestreamer is a glorified (video) tape recorder controlled by the computer and is used mainly for backup storage purposes.
Task manager -- This is the Acorn icon at the far right of the iconbar. It is an application that controls the allocation and use of memory within the computer.
TCP/IP -- (Transfer Control Protocol / Interface Protocol) This is a standard protocol for transferring data between different computers on a LAN or via modem link.
TIFF (files) -- (Tagged Image File Format) A very versatile format for storing and transferring bit-mapped graphics.
Title bar -- The bar along the top of a window that contains the name of that window.
TLB -- (Translation Look-Aside Buffer) This is part of an ARM processor which helps it to access different areas of memory more quickly. Basically, it's the bigger the buffer the better!
Tokenised -- When a Basic program is stored on disc, it is usually stored with each keyword represented by a single byte rather than as a string of ASCII codes. These single bytes are referred to as tokens.
Toner -- This is the fine powder used in a laser printer (or photocopier).
Tracking -- In some applications, the spacing between individual letters within a block of text can be controlled -- this is called tracking. If the tracking is changed, the spacing between all the characters is increased or decreased. This is distinct from kerning which relates to the spacing between individual pairs of characters.
TRM -- (Technical Reference Manual) Term used to refer to the optional hardware manual for Acorn computers.
TSV -- (Tab Separated Variables) A standard way in which data is stored in a file where the items of data are separated by tab characters.
U
V
Vapourware -- A derogatory term for software that is being advertised but isn't actually available -- it is often said to be available "real soon now"!
VDU -- (Visual Display Unit) The monitor or television used to display the output of the computer.
Vector graphics -- It is possible to represent a picture on a computer by using a series of lines, shapes, characters etc. When such pictures are printed, the resolution of the pictures produced is only limited by the resolution of the output device. (This contrasts with bit-mapped graphics -- see above. For example, the Draw application produces vector graphics whereas Paint produces bit-mapped graphics.)
VESA -- (Video Electronics Standards Association)
VGA -- (Video Graphics Array) A graphics standard from the PC world -- 640×480.
VIDC20 -- (Video Controller) The video and audio controller designed by ARM Ltd and used in the Risc PC.
Virtual memory -- A method by which an application, which requires more RAM memory than a computer actually has, can still operate. It is done by using parts of a hard drive's memory as an extension of the real memory, the information being swapped in and out by the operating system, as and when it needs to be accessed by the application.
Virus -- A computer program which can replicate itself (unbeknown to the user) in various storage devices and in several places on one storage device. As discs are taken from one computer to another, the virus can be spread to more and more computers. Often, the effect of these programs is to cause malicious damage to data within the computer system.
VRAM -- (Video RAM) This is a bank of high speed RAM used to store the information for the screen display. It can usually (as in the Risc PC) be accessed by the computer's processor and by the video controller at the same time. The computer accesses it as necessary to change the screen display and the video controller accesses it on a continuous basis to constantly generate the signals the monitor needs to display the information set up by the computer.
W
WIMP -- (Windows, Icons Mouse and Pointer) A method by which a user can interact with a computer without having to learn lots of special words. It provides a much more intuitive 'view' of the computer and its facilities than non-WIMP operating systems provide.
Winchester -- Old-fashioned term for a hard disc, named after the inventors of the technology.
Word -- A group of bytes considered by the cpu to be a unit of data. In Acorn 32-bit computers, a word is
WP -- (Word-Processing) -- In the early days of microcomputers, all they could do was allow you to handle text to create documents, i.e. to process words. These days, however, many of the programs that are referred to as word-processors can also handle pictures, so the distinction between WP and DTP is becoming less clear.
Writable icon -- A submenu into which you can type some information such as a filename.
Write-protect -- Open the tag at the corner of a floppy disc in order to protect the contents from being edited or accidentally deleted.
WYSIWYG -- (What You See Is What You Get) In the days of text-based word-processing, the screen display would only gave an indication of which words would appear on a given printed page but often not much more than that. WYSIWYG describes a system where the screen display shows the size and positioning of all the text (and graphics) exactly as it will appear on the printed page.
Whetstones -- (I think) This is a floating point version of the Dhrystones test.
Sources
I acknowledge, with grateful thanks, the many Archive subscribers who have contributed ideas and definitions for this glossary. I would also like to acknowledge various books that I have consulted that have been most useful in compiling this glossary:
