Glossary: C

This page contains glossary terms beginning with the letter C.
!-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Word or Term Description or Explanation
C a high level compiled language
C++ this is an object-oriented version of the C language
C# pronounced "see sharp" - Microsoft's improved version of the C/C++ family of programming languages, bearing more than a passing resemblance to their illegal version of Java, and a key part of their .NET (pronounced "dot net") strategy
Cache an area of RAM set aside for the fast storage and retrieval of a certain type of data, e.g. font cache - all Acorn computers since the A5000 have had a cache incorporated into the processor, giving a massive improvement in performance - the ARM 2 and ARM 250 don't have a cache
CAD Computer Aided Design - a computer-based application that allows users to draw, design and model engineering objects
Caps short for 'capitals'
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
Careware software for which the author requests a nominal contribution to some suggested charity in lieu of a fee
Carrier the tone generated by a modem, on which data is carried
CC Carbon Copy - an email header listing recipients to whom a copy of the message should be sent - all recipients will see this list
CCITT international body that ratifies recommendations for telecoms standards
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
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
CDFS filing system used for accessing CD-ROMs
Centronics the company that invented the parallel port of the same name
CERT Computer Emergency Response Team - a group dedicated to raising awareness of computer security issues and responding to security incidents
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
Chatbot an interactive program for conversing with humans in natural language
CIX Commercial Internet eXchange - an agreement among Internet service providers on the commercial use of the Internet - not to be confused with Compulink Information Exchange which is a major UK BBS
ClariNet a hierarchy of newsgroups on Usenet that carries commercial information from official sources - access to ClariNet is chargeable
Clear (files) a standard format for storing and transferring 24-bit pictures
CLI see Command line interpreter
Click press the (left hand) button of the mouse
Client a program on a computer attached to the Internet which is used to access certain services, e.g. a Web client is a program by which you can access the Worldwide Web - the term client refers to the idea that the program provides an easy-to-use access to another more basic program
a computer receiving information from a server is also referred to as a client
Clock speed a measure of the rate at which the main processor is being run, measured in MHz
Close icon the icon at the top left of each window, next to the back icon which allows you to close the window
CMOS complementary metal oxide silicon (but you don't need to know that!) - a technology used to make computer chips - see also CMOS RAM (next)
CMOS RAM low-power RAM chips that are used in most Acorn computers to store certain characteristics of the way the user wants to computer to start up- the information in this CMOS RAM is held with a small battery so that it is not lost when the main power is switched off
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 RiscPC "only" gives 16 million colours but the extra 8 bits can be used by the computer to produce various different special effects
Command line a way of accessing a service by typing in textual commands
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
Command line
pressing <f12> allows you to type command lines into your RISC OS computer - these are then interpreted by the CLI
Command Shell a process which receives and processes a text command string - typically invoked in either of two modes: direct keyboard input or a call from another process - output may be to screen, file or yet another process
Compact Flash (CF) Card a form of Flash Memory on a removable card - often used in digital still cameras such as Mustek
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
there are various mathematical techniques which can be used to store (and transmit) computer data using a smaller amount of memory than the uncompressed data represents - 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
Compuserve a large international BBS with limited Internet access
Concept keyboard an input device consisting of a flat panel, usually A4 or A3 sized, that has a matrix of pressure switches below the surface - different sheets, called overlays, can be placed on top of the panel to show the user which areas to press to get certain responses from the application software that is currently running - they are particularly useful in primary school or special needs situations
Configuration a collection of settings and options 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
Cookie a message given to a Web browser by a Web server - the browser stores the message in a text file called cookie.txt. The message is then sent back to the server each time the browser requests a page from the server
the main purpose of cookies is to identify users and possibly prepare customized Web pages for them - when you enter a Web site using cookies, you may be asked to fill out a form providing such information as your name and interests - this information is packaged into a cookie and sent to your Web browser which stores it for later use - the next time you go to the same Web site, your browser will send the cookie to the Web server - the server can use this information to present you with custom Web pages - so, for example, instead of seeing just a generic welcome page you might see a welcome page with your name on it
the name cookie derives from UNIX objects called magic cookies - these are tokens that are attached to a user or program and change depending on the areas entered by the user or program - cookies are also sometimes called persistent cookies because they typically stay in the browser for long periods of time
Coprocessor (1) see Second processor
Coprocessor (2) also used of any hardware such as an FPA that is used to extend the instruction set of the CPU
CPS (1) cycles per second
CPS (2) 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
Cross-posting sending the same article to more than one Usenet newsgroup at a time
CSLIP Compressed SLIP
CSS Cascading Style Sheets - an extension of HTML which gives both website designers and users more control over how pages are displayed, by using style sheets
CSV Comma Separated Variables - a standard way in which data is stored in a file where the items of data are separated by commas
Cyberspace the virtual world that exists within computer networks
Cyrix a microprocessor manufacturer

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