Computer Glossary P
Packet This is a unit of data, which is typically a part of a file,
that has been prepared for transmission across a network,
usually the internet.
Parallel Port A 25-pin port on a PC that uses eight wires
to transfer one byte of data at a time at speeds up to
100KBps (kilobytes per second) and is used mainly for
connecting printers.
PCI peripheral component interconnect. The most common bus
design for motherboards and expansion slots.
PCL printer control language. A language developed by HP to
control its LaserJet printers and supported by virtually all printer
manufacturers. It consists of commands called ‘escape
sequences’ that programs use to tell the printer about the
number of copies to print, the resolution and page formatting.
Peer-to-Peer A small network of PCs that do not use a central
server. Each user can decide what resources on their PC they
wish to share.
Pixel Pitch On flat-panel displays it’s the pixel pitch that
determines how many dots can be displayed on the screen.
The lower the pixel pitch, the more dots will be used to build
up an image.
Platters Circular discs within a hard drive on which data is
stored. Typically 3.5in diameter.
Plug and Play Sometimes shortened to PnP, this is a standard
which allows a PC to automatically recognise when compatible
devices, such as printers or monitors, are connected to it.
Previously, it was necessary for the user to inform the PC that
new hardware had been attached in order to get the device in
question working.
POP point of presence. The location of the nearest node for an
ISP, this is the number you dial to connect to the internet. A
POP necessarily has a unique internet protocol address.
Post power-on self test. The first process a PC runs when it is
switched on that checks the memory, processor, graphics and
so forth are all functioning. A series of beeps indicate if errors
are found – one beep usually means that all is well.
PostScript Page A description language developed by Adobe
Systems that describes each element as a vector pair, rather
than telling the printer where to place each dot of ink or toner.
It is more suited to graphics printing and has wider application
than PCL as it can produce better output quality at higher
print resolutions.
Proxy Server A server that sits between your browser and a
web server. The proxy server intercepts all requests by your
web server and checks that it doesn’t have the requested
web page stored on its hard disk. If it has, the proxy server
returns the requested web page from its hard disk. Proxy
servers help to speed up internet access and can also be
used to filter out requests for unsuitable web pages.
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