Archive Magazine CD 1995/Archive Magazine CD 1995.iso/glossary/text

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This glossary has been created on the basis that someone may read a word
or a technical term or an abbreviation within the pages of Archive
magazine and think, “What does XXXX mean?”. If you think that about
a word, look it up in this glossary. If it does not appear, please ring,
write or fax and tell us what it was that you wanted to know.

Some of the definitions will be specific to Acorn computers whereas
others are also more generally applicable.

!

! − (pronounced “pling”) A term used to denote an exclamation mark!

10base2 − An Ethernet standard that uses BNC connectors and coaxial
cable. Also known as “thin wire” Ethernet.

10base5 − An Ethernet standard that uses 9-pin D-type connectors and
special cable. Also known as “thick wire” Ethernet.

10baseT − An Ethernet standard that uses telephone connectors and
telephone cable. Also known as “Cheapernet”.

A

Action button − A button in a dialogue box which causes some action to
occur.

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 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.

Archive − The best Archimedes magazine ever, or... A backup of some
data.

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

Back icon − The icon at the top lefthand corner of a window which allows
you to push the window to the back of the desktop.

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 − (Basic input/output system) This is the part of a PC compatible’s
operating system that is held in ROM, allowing the computer to start up
and load the rest of its operating system from disc. (cf RISC OS
computers where the whole of the operating system, plus a few extra
goodies, are held in ROM and are available at switch-on.)

Bit − (Binary digit) 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 pixel) The number of 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.

Bug − Error in a computer program.

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 refers to the
number of parallel tracks − the wider the bus, the faster data can be
transmitted down it.

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 red 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.

CLI − (Command line interpreter) Pressing <f12> allows you to type
command lines into your RISC OS computer. These are then interpreted by
the CLI.

Close icon − The icon at the top left of each window, next to the back
icon which allows you to close the window.

CMYK − (Cyan, Magenta, Yellow, Key) A method of specifying colour by
using the amounts of the three primary (subtractive) colours plus the
amount of black (Key).

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 operating system commands
by typing them in from the keyboard. If you press <f12>, a 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 compiler 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.

Control codes − Special non-printing ASCII codes which cause a device to
perform some electronic or mechanical action, e.g. ASCII 10 is linefeed,
13 is a carriage return and 12 ejects the paper or clears the screen.

Coprocessor − See Second Processor.

CPS − (Characters per second) A way of measuring the speed of dot matrix
or inkjet printers.

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.

CRC − (Cyclic redundancy check) This is a way of checking for errors in
stored and transmitted data.

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.

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 read,
it can support anything between eight and fourteen expansion cards!
Currently, the maximum is eight but we think it is theoretically
possible to have more.)

Debug − Remove the bugs (errors) within a program.

Debugger − An application written to provide tools to aid the process of
finding errors in a program.

Decompression − See under compression.

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 of
a particular test program it can perform 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 needs 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. (For most practical purposes, there is very little
difference between DR-DOS and MS-DOS.)

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) A set of techniques for modifying sound
signals. It involves digitising the signals, performing various
mathematical processes on the data and then turning the resulting data
back into an analogue signal.

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.

Editor (1) − An application that allows you to edit the contents of
a file.

Editor (2) − Someone who is daft enough to take on the task of putting
together a massive glossary!

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.

Error box − A special type of dialogue box that gives information to
a user about the type of error that has occurred, requiring him to
acknowledge that it has been read.

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. The most common standard of
floppy drive used now is 3½". Some 5¼" drives are still in use but the
8" floppies have virtually all been consigned to the museum of computer
technology.

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 by doing
them in hardware rather than in software.

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, all prefixed with an “F”. 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, and the displays were only
able to show text characters, not graphical images. 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.

HD − (Hard drive)

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.

Hourglass − This is the egg-timer thing that appears on the screen all
too often, telling you that the application is taking a long time to do
something and that it doesn’t want interrupting.

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 input received 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.

ISA Bus − (Industry Standard Architecture) This is a “standard”
expansion interface as used on PC compatibles.

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.)

Kernel − The main part of the RISC OS operating system.

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. It can also refer to
shifting characters up or down relative to one another.

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.

Leafname − The last part of the pathname, i.e. the name of the file or
directory being referred to.

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.

MPC − (Multimedia Personal Computer) The “standard” multimedia computer
used in the PC world.

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 in certain 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.
(Actually, I think it’s a bit of a con. The cpu can really only does one
job at a time but what it does is to do a little bit of each task every
fraction of a second.)

N

Network − A means of connecting a number of computers together so that
they can share data and the use of peripherals.

NFS − (Network Filing System) A RISC OS filing system that uses Acorn’s
Econet network system.

O

Obey file − A file of commands prepared for execution by the RISC OS
command line interpreter.

Object code − the machine-executable code produced by a compiler.

Object oriented − The approach used in conventional programming is to
have a number of procedures or routines which can work on some data.
There is no conceptual connection between the data and the operations
which are performed on it. In contrast to this, object-oriented
programming works on a concept of objects, which consist both of data
fields (similar to a structure in C) and of a list of methods which may
be applied to that data. For example, you could define an object point
(with data x and y, both integers), and define a move method on it to
change these fields.

One of the most useful concepts which may be derived from this is
inheritance − an object can be defined as a sub-type of another object,
and in doing so inherit all its methods (and data fields), but may also
add its own. As an example, you could define a circle object with data x
and y (inherited from the parent point object) but with another data
field, radius. Similarly, the circle would inherit the move method
(which would not have to be rewritten), but could also have a resize
method added to it.

The result of these changes in approach is that it is often easier to
implement large programs, since it is harder to get confused about how
a piece of data should be used, and less code needs to be rewritten.
Object-oriented languages include Modula-3, C++ and Objective C.

(Well, you wanted to know what it meant, didn’t you?! Thanks to Andrew
Garrard for that definition. Ed.)

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 as 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 − See above)

OS graphic unit − A unit for defining graphics under RISC OS so that
they are independent of the current screen mode. There are nominally 180
OS graphics units to the inch.

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.

Pane − A dialogue box that is attached to a particular window, e.g. the
toolbox at the side of a Draw window.

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.)

Parity − A method of checking for errors in transmitted or stored data.
An extra bit (the parity bit) is added to each ASCII character so that
the number of ‘1’ bits is always odd (or always even).

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 e.g.
SCSI::Paul105.$.Archive.Bits.!Glossary

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 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 by Intel
Corporation.

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'.

Pop-up menu − A menu available by clicking an icon in within a dialogue
box. The icon is often placed alongside a display showing the current
setting of that option.

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 currently 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.

Qwerty (keyboard) − Look at the six characters at the top left of your
keyboard and you’ll see what it’s called a qwerty keyboard. (In France
it would be AZERTY and in Germany QWERTZ.)

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. The cartridge 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 three coloured phosphor dots of
these three colours.

RIP − (Raster Image Processor) This is a device used in the printing
industry to produce a very high resolution output.

RISC − This is an acronym for Reduced Instruction Set Computer.
Companies like Acorn (and many years later, Apple, though not yet,
apparently, Intel) 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. Acorn
made 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. (N.B. This explanation is a gross over-simplification
which doesn’t do justice to the brilliance of the designers of the Acorn
RISC processors!)

RISC OS − This is the operating system used on Acorn’s RISC-based
computers.

RISC_OSLib − A library supplied with Acorn’s ANSI C compiler designed to
help you program applications that run in the RISC OS desktop.

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.

Scroll arrow − The arrows within a window that are used to allow you to
scroll through a document or list or to move around the contents of
a window that is too big to display in the current size of window.

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.

SCSIFS − A RISC OS filing system used for communicating with devices
attached to the SCSI interface.

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.

Select box − A rectangular box used to outline an area within which any
objects are selected.

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. It can also be done by using
<ctrl-shift-f12>.

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.

Sprite pool − An area of memory used by RISC OS for storing sprites.

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.

Template − A set of windows and dialogue boxes that have been designed
for use within an application.

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!

Toggle size icon − The icon at the top righthand corner of a window that
is used to extend and contract a window between its maximum size and the
size and position to which you last reduced it.

Tokenised − When a Basic program is stored, 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.

Toolbox − A window or pane of tool icons. It may be free-standing or
attached to another widow.

Toner − This is the fine powder used in a laser printer (or
photocopier).

TPI − (Tracks per inch) This is one way of specifying the amount of data
you can store on your floppy discs, e.g. 800Kb 3½" discs (DD) are
135tpi.

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.

Transparency mask − An optional part of a sprite that defines which
pixels of that sprite are transparent.

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

U think of something − I can’t!

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 Adapter or 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

Weight − This refers to the density of the characters within a typeface
− e.g. bold, light, extra, demibold, extrabold, etc.

WIMP − (Windows, Icons, Menus 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.

Window manager − This is the official name for the RISC OS WIMP system.

Word − A group of bytes considered by the cpu to be a unit of data. In
Acorn 32-bit computers, a word is four 8-bit bytes.

WP − (Word-Processing) − In the early days of microcomputers,
word-processing was limited to handling text to create documents. 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.

(WITHIWIG is another version of WYSIWYG but said with tongue in cheek.
It applies to those applications which are not quite what they claim!)

Whetstones − This is a floating point version of the Dhrystones test.

X

XGA − (Extended Graphics Adapter or Array) The definition varies (as
well as the name) depending which book you read but it is roughly 1024 ×
768 in lots of colours!

Y

Y do we have to have something for every letter?

Z

Zzzz − This is what happens to anyone who tries to read right the way
through a glossary like this one!





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 I have consulted that have been most
useful in compiling this glossary:

Acorn RISC OS Style Guide − Acorn Computers Ltd − 1-85250-148-0

Acorn Risc PC Welcome Guide − Acorn Computers Ltd − 1-85250-143-X

Acorn User Magazine − various issues

Archimedes World Magazine − various issues

DTP at a Glance − Rob Pickering − Bookmark Publishing − 1-85550-002-7

RISC OS First Steps − Anne Rooney − Dabs Press − 1-870336-83-6.