| Word or
Term |
Description
or Explanation |
| Packet switching |
the technique in which a stream of data is
broken into standardised units called 'packets', each of which contains
address, sequence, control, size and error-checking information in addition to
the user data |
| 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 RiscPC, 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) |
| Pascal |
originally developed in the late sixties as a
programming language - it is the only main third generation language to be
named after a person rather than a mnemonic - it was developed so that the
developer had a language to teach his computing undergraduates which was simple
and relatively easy to learn - it has been refined over the years to remove
some deficiencies, one of which was it was the only 3rd generation language
which originally had no string data type |
| Password |
when accessing a remote site, especially
where certain services are only accessible to registered individuals, the
system my require you to type in a code word or words to prove that you are who
you say you are, and that password is necessary in order to grant you
access |
| Patch |
extra code added in to the operating system
to replace other code that has been found to be buggy or simply in need of
improvement |
| 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 |
| PC Card |
a PC processor on a separate card that can be
used as a second processor in a RiscPC |
| 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 |
| PCB |
Printed Circuit Board - a piece of insulating
material covered with conducting tracks, used to interconnect electronic
components to make up an electronic circuit |
| PCI |
a computer bus: width 32 or 64 bits; clock 33
MHz; maximum transfer rate 133 Mbyte/s to 267 Mbyte/s - independent of
processor type |
| PCMCIA |
Personal Computer Memory Card International
Association - a committee which has set out the standard format for credit
card-sized plug-in modules for personal computers, particularly portables -
modules include memory cards, modems, sound cards, etc. |
| PD |
Public Domain - software that is released
unconditionally, so that anyone can copy it, alter it, or use it as they wish -
the author retains none of the exclusive rights associated with copyright - PD
is often used incorrectly to refer to freeware or shareware |
| PDA |
Personal Digital Assistant - a handheld unit
which in non-PC oriented, e.g. Psion |
| PDF (1) |
Portable Document Format - the native file
format for Adobe Systems' Acrobat - PDF is the file format for representing
documents in a manner that is independent of the original application software,
hardware, and operating system used to create those documents - a PDF file can
describe documents containing any combination of text, graphics and images in a
device-independent and resolution-independent format - these documents can be
one page or thousands of pages, very simple or extremely complex with a rich
use of fonts, graphics, colour and images |
| PDF (2) |
Printer Definition File - a file within the
RISC OS system that defines how pages are printed on a particular printer -
carrying details of things like page size, margin width, special codes needed,
etc. |
| PDF reader |
a program which enables PDF (Portable Document Format) files to be displayed on screen
(but not created) and (possibly) to be printed out |
| PEM |
Privacy Enhanced Mail - Internet email which
provides confidentiality, authentication and message integrity using various
encryption methods |
| 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 |
| PGP |
Pretty Good Privacy - secure encryption using
a public key system |
| 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 |
| Ping |
Packet Internet Groper - about the simplest
Internet program - it simply sends an "Are you there?" type message and reports
back how long it took - can be useful to see if you can make contact with
another machine, e.g. ping gate.demon.co.uk |
| 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 |
| plan file |
see .plan file |
| Pling (!) |
under RISC OS, if a directory name starts
with a pling, it is taken to be an application |
| Plonk |
used to represent the sound made by someone
behaving stupidly or offensively in a newsgroup as he falls into a user's kill
file, often written "*plonk*" and used as a form of public ridicule |
| PNG |
Portable Network Graphics - a format for
storing and displaying images, designed to improve upon the GIF format |
| Pocket Book |
see Psion
3 |
| Podule |
see Expansion card |
| PoP |
Point of Presence - a local phone number for
access to Pipex, Demon or other Internet providers |
| POP/POP3 |
Post Office Protocol - POP is a networking
protocol which allows users to download mail messages from a central mail
server or "Post Office" - it is used in situations where the machine belonging
to a user is not always available (e.g. a machine which is switched off when
not in use, or one which only connects to the Internet occasionally via a
dial-up link) - internet mail for the user is delivered to the Post Office
machine and held there, awaiting collection by POP - there are several versions
of the protocol, the most recent (and widely used) being version 3 which is
described in Internet RFC 1725 and commonly referred to as "POP3" - "POP",
without any qualifying version number, normally refers to version 2 which is
described in Internet RFC 937 |
| comparing POP3 with SMTP, the other main
e-mail transfer protocols, the major difference is the decision as to which
party is in the driver's seat - with SMTP, the server is in charge of delivery,
the client has to wait passively for the server to send the messages to it -
with POP3, the client is in charge - it interrogates the server to determine
what messages are available, and then requests them individually |
| POP requires a password and is therefore
secure, while SMTP does not require a password and therefore can be used by
anyone - this causes problems when spammers use a node other than their own to
send mail - therefore preventing their own ISP from knowing that they sent the
spam, and preventing recipients from knowing where the mail came from - because
of this, there are moves afoot to make both sending and receiving mail using
POP rather than a mixture as it allows the mail to be verified - it is coming
from someone who is allowed to use that account - potentially reducing
spam |
| Pop-up menu |
a menu available by clicking an icon within a
dialogue box - the icon is often placed alongside a display showing the current
setting of that option |
| Portal |
a website that aims to be a "doorway" to the
World-Wide Web, typically offering a search engine and/or links to useful
pages, and possibly news or other services - these services are usually
provided for free in the hope that users will make the site their default home
page or at least visit it often - most portals exist to generate advertising
income for their owners |
| Post(ing) |
to put an article/message onto a
newsgroup |
| Postmaster |
the person who deals with mail and answers
mail-related questions on an Internet site - on a BBS, the postmaster is
usually the sysop |
| 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 |
| PPP |
(a.k.a. P3) - Point to Point Protocol - a
standard for transmitting Internet Protocol (IP) data packets over phone lines
- this is a newer and more robust protocol than SLIP - N.B. this is NOT for
transfer of mail - it just transfers data, which could, of course, contain
mail, but the protocol knows nothing about this |
| 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 |
| Printer server |
a device or piece of software on a computer
to provide a 'network connection' for a printer - typically the printer would
have a parallel port or USB connection and the printer server would allow
anyone on the network to print to the printer - you can also buy printers with
a network connection and printer server built in |
| PRM |
Programmers Reference Manual - a set of
manuals covering many highly technical programming details of the RISC OS
operating system |
| Processor |
see CPU |
| Program |
a set of instructions which tells a computer
how to carry out a particular task |
| Prolog |
a high level computer language often
associated with artificial intelligence programming |
| Prompt |
when the host system asks you to do something
and waits for you to respond - for example, if you see "login:" it means type
your user name |
| Protocol |
an agreed set of procedures which allows for
the orderly transfer of data between two hosts via a communications network -
it is essentially a common language which enables hosts to interwork. Examples
are TCP, IP, FTP, HTTP, etc. |
| Protocol
stack |
a set of protocols which, together, form a
hierarchy - the protocols at the top of the stack use the protocols lower down
to do their work - for example, consider a mail server on host A, delivering a
message to a mail server on host B - the two servers communicate using the SMTP
application protocol, but do this via a TCP connection - the TCP connection is
achieved by firing IP packets into the network - the IP packets are sent over a
serial link using SLIP - the individual binary digits of the SLIP packet are
encoded as a series of electrical impulses on a copper twisted pair - inside
host B, the reverse process occurs to reconstitute the IP packet, which is sent
up through the TCP layer to the application protocol |
| Proxy server |
a web server that fetches pages at your
request and stores them in its own memory - this is usually used in conjunction
with a cache so that if you fetch the same page again, it will come from the
cache rather than having to be refetched - if you have a number of users who
are all looking at a similar set of documents (e.g. a class of students looking
at the same site) a proxy server on your local net can speed up access because
a given page only needs to be fetched from the 'outside world' once and from
then on it is returned from the cache |
| PS/2 port |
the type of port allowing connection of mouse
and keyboard to the computer |
| Psion 3 |
a palmtop computer which was highly
successful and incorporated a large number of features of a desktop computer in
something which would fit in a pocket, and included a word processor,
spreadsheet, database, clock, and various other things - the Psion 3 was cloned
by Acorn to give the Acorn Pocketbook - it was superseded by the Series 3a
which Acorn cloned into the Pocket Book II - that has since been superseded by
the Psion 3c and the Psion 5 (there was no Psion 4, as 4 is considered the
number of death in Japan where Psions sell quite well) |
Public Key
Cryptography |
a method of encryption whereby a public key
is made available by someone to those people who want to send messages to that
person - the public key is used to encrypt the data, but only the private key
held by the owner can decrypt the data |