Archive Magazine CD 1995/Archive Magazine CD 1995.iso/discs/prog_disc/volume_7/issue_09/glossary/Linefeeds

Text File | 1994-05-10 | 26.5 KB | 621 lines

A

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 direc
tory. 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.

B

Backplane − A small printed circuit board with connectors on it that
allows you to plug in a number of expansion cards.

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.

Bit − A bit is the smallest unit of binary data. It has two values,
0 and 1. A group of 8 bits of data 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.

Byte − A byte refers to (usually) 8 bits of binary data stored
within a computer’s memory or on a data storage medium.

C

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 orig
inally 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.

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 either black or white. If it were
defined by two bits, it could have 4 (2^2) different colours, four
bits would provide (2^4) 16 different colours, 8-bit provides 256
(2^8) 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.

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 techni
ques 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.

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.

D

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.)

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.

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.

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, applications or other
directories. These directories in turn can contain more informa
tion and/or further directories. This system of directories within
directories is called a hierarchical data structure.

Double density floppy discs − Discs that can store approximately 800Kb of
data when formatted.

DOS − (shorthand for DR-DOS or MS-DOS) These are the operating
systems most commonly used on IBM PC computers and compatibles.
Both 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.

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 them 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.

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.

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.

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.

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.)

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

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 informa
tion. 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 ROM, 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.

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.

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 charac
ters 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.

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 = 2^30 = 1024 × 1024
× 1024 = 1,073,741,824 bytes.)

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 12 Mbytes!

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 density floppy discs − Discs that can store approximately 1,600Kb of
data when formatted under ADFS or up to 14,400Kb when formatted
under MSDOS.

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.

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.

Input focus − The output from the keyboard can be directed to one and
only one window at a time. The window currently receiving informa
tion 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.

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 2^10 = 1024 bytes.)

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.

M

Mb − (Megabyte) Approximately one million bytes of computer data.
(Actually, it is 1K × 1Kb = 2^20 = 1024 × 1024 = 1,048,576 bytes.)

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.

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.
(Check if this applies to Risc PC.)

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.

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.

N



O

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 use alternative
operating systems such as DR-DOS and MS-DOS by adding the appro
priate software.

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.

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

Parallel − A device or communication channel is said to be parallel if
the data is sent several bits at a time down several (usually 8)
parallel wires.

Parent directory − The directory within which the directory you are
currently dealing with is stored. (It is the opposite of a
subdirectory.)

PC Emulator − An application that can work within RISC OS or as a
separate program taking over the whole of the computer’s process
ing 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.

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’.

Printer manager − An application that oversees the printing process.

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.

Removable hard 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.

Resources − The various programs and data files which an application
uses to perform its task.

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.

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.

S

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.

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.

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 seven different ‘devices’ together.

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.

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.

Subdirectory − Within any directory, you can store files and other
directories. A directory that appears inside another directory is
referred to as a subdirectory.

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

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.

Title bar − The bar along the top of a window that contains the name
of that window.

U



V

Vapourware − A derogatory term for software that is being adver
tised 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.

VIDC20 − (Video Controller) The video and audio controller designed
by ARM Ltd and used in the Risc PC.

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

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.