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Key Terms for A451
Terms in this set (192)
A computer system that form part of an electronic device.
The lowest level of an operating system that controls the hardware.
Something which is designed for one particular purpose.
Hypertext mark up language - a text based system for defining web pages.
Portable document format - a file standard that displays a document accurately on any computer platform.
International Organisation for Standardisation (ISO)
The world's largest standards developing organisation. It produces standards for engineering, agriculture and medicine, as well as for information technology.
Transmission control protocol/internet protocol - a set of standards that control how data is sent across networks including the internet.
The internal, logical structure and organisation of the computer hardware.
A system of numbers using only two digits 0 and 1 (also called the 2-base system).
Central processing unit of the computer containing the control unit, ALU and cache memory.
The control unit works with the CPU to control the flow of data within the system.
The ALU performs all the arithmetic and logical operations within the CPU.
Random Access Memory (RAM)
Main memory of a computer that stores data, applications and the operating system whilst in use. When the power is turned off RAM loses its data.
Special high speed memory used by a computer.
Solid-state memory used as low cost secondary storage in portabel devices and as removable memory.
Technology based on electronics with no moving parts, for example transistors and capacitors as used in memory chips.
Non-volatile storage used to store programs and files that need to be kept even when the power is not on.
The is the process of fetching the instructions from memory, decoding them and the executing them so that the CPU performs continuously.
Read only memory (ROM)
A store for data in a computer that cannot be overwritten. Data in ROM is always available and is not lost when the computer is turned off.
The electronic device in a computer that controls the timing of signals.
A part of a computer architecture that transfers data and signals between components of the computer.
The central printed circuit board (PCB) that holds the crucial components of the system.
A CPU with multiple processors.
Binary digit 0 or 1.
Data lost when there is no power.
Data retained even when power is turned off.
A section of the hard disk used as if it were RAM to supplement the amount of main memory available to the computer. Used when there is not enough main memory to run the programs required.
A circuit that produces an output based on the inputs.
A logic gate that outputs the opposite value to the input.
A logic gate that outputs 1 if both inputs are 1.
A logic gate that outputs 1 if either, or both, of the two inputs are 1.
A method for recording all possible input combinations and determining the output for each.
A circuit made by combining a sequence of logic gates.
A method for expressing mathmatically a logic circuit.
A hardware device used to input data into a computer system for processing.
A device that uses labelled keys to enable data input into a computer.
A device that controls the movement of a pointer on screen, based on its own movement, and allows the user to select an object by pressing a button.
A touch sensitive surface that allows the user to select, control and move objects by touching icons and symbols using fingers.
A device for capturing sound.
A decive to capture still or moving images.
A pattern of thin and thick lines representing a number that can be scanned by a reader for input into a computer system.
Radio frequency identification uses radio frequencies to represent a number that can be scanned for input into a computer system.
A device that can detect physical conditions such as temperature, weight, light, sound etc.
A device that can display images and text.
A device to produce physical copies of output from a computer system.
A device to output sound.
A device to produce physical movement based on output from a computer system.
Magnetic hard drive
Secondary storage device using magnetised platters to store data and files.
Secondary storage device using laser to read (and write) data to a reflective surface. For storing files to be distributed or transferred or for backup of important files.
A type of optical device with a capacity of 700MB.
A type of optical device with a capacity of 4.7GB.
A series of steps designed to solve a mathematical or other problem.
A set of commands that a processor can recognise and act upon.
A stroed set of instructions for a computer to execute.
The programs that run on a computer.
Software designed to carry out a useful real-world task.
A combincation of hardware and operating system that supports the running of particular applications.
A way of writing instructions for a computer to execute.
Instructions in binary used by the CPU.
A programming language that is directed at controlling each machine.
A programming language that resembles a natural language. Each instruction translates to many machine instructions. It is problem based rather than machine based.
Formal methods to guide the writing of software.
The boundary between systems or between systems and humans.
Translation software that converts high-level source code into machine (object) code.
Translation software that converts source code or user input into machine code which is immediately executed one instruction at a time.
Software that combines together a number of separate object code files.
Software that helps a programmer track down faults in a program.
The software taht controls the hardware. It acts as an interface between the user and the hardware and also between applications and the hardware.
The ability of a program to load itself. Some small devices load their applications directly without the need for a conventional operating system.
A server that handles requests to a website.
A combination of hardware and operating system that supports the running of particular applications.
The lowest level of an operating system and that controls the hardware.
A program currently being executed.
The place where typed commands are given to the operating system.
The boundary between the computer and the user.
Graphical User Interface
A user interface that makes use of icons for interacting with the user.
A picture on screen that represents a file, a program or an action.
Software that provides a traditional text based interface to an operating system.
A program that enables communication between a computer and a peripheral.
A signal to the operating system to stop what it is doing and perform a different task instead.
A small application that performs one specific task.
A computer system that forms part of an electronic device.
Software that is stored permanently in a device, such as control programs for devices.
Software or hardware that requests services from a server.
Software that provides services to a client, or the hardware that is running it.
A small program designed to carry out a limited maintenance task.
The process of discovering possibly harmful viruses in a computer system.
Malicious software that detects what a suer is doing and sends the details back to the originator.
Harmful software that is disguised as something useful.
Software and/or hardware that limits access to and from a computer system.
The process of arranging files and date bytes on a secondary storage device.
A utility that brings together file fragments on a disk and collects all the free space in one area.
Software used for entering source code when writing a program.
An editor that automatically sets out program code in an easy to read way.
A low-level programming language that used more memorable mnemonic codes and lables to represent machine-level code. Each instruction corresponds to just one machine operation.
Software that translates assembly language code into machine code.
Off the shelf
Software that is aimed at many users and sold 'as is'.
Software developed specially for one or a few customers.
A system of numbers used ten digits, 0 and 1-9 (also called the base-10 system)
4 bits or half a byte
When a number becomes too large to fit into the number of bits allocated it is said to 'overflow' and some bits are 'lost' leaving an incorrect value.
The base-16 number system.
The characters available to a computer
ASCII (American Standard Code for Information Interchange)
7-bit system to coe the character set of a computer.
Up to 32-bit system to code the character set of a computer (usually 16-bit or 32-bit versions).
The smallest element of an image. Pixels are the dots that make the image on screen.
The number of bits used for each pixel or dot. The more bits, the more colours that can be represented.
The number of pixels or dots per unit, for example ppi (pixel per inch), often referred to as dpi (dots per inch).
Information about the image data that allows the computer to recreate the image from the binary data in the file. This must contain the height and width in pixels and the colour depth in bpp (bits per pixel).
Graphics format consisting of a matrix of dots.
Refers to continuously changing values.
The number of times the sound is sampled per second, measured in Hz (100Hz is 100 samples per second).
The bit rate is the space available for each sample measured in kilobits per second (kbits/s). (128 kbits/s is 128 kilobit per second of sampled sound).
A location in main memory used to store data or instructions.
An instruction is decoded by the CPU into two parts - the operator and the operand.
Special fast access part of the CPU that stores data in use by the CPU.
A register in the CPU that keeps the address of the next instruction.
This is the part of the instruction that tells the CPU what to do.
This is the part of the instruction that tells the CPU what to apply the operation to.
A register in the CPU that stores data currently being used by the CPU.
A file of items one after another.
A serial file in order.
Indexed sequential file
A sequential file that is accessed using an index, which is a separate file.
Flat file database
Database consisting of only one table.
A characteristic of something stored in a database.
All the data baout one item in a database.
Something that we store data about in a database.
A characteristic of an entity. It becomes a field in a data table.
The unneccesary repetition of data.
The state of data being as it should be, reflecting reality.
The process of checking data as it is input to ensure that it is reasonable.
The process of checking that data is true or correct.
One to many
A relationship where one record in a table may have links to many records in another table.
Entity relationship diagram
A diagram that shows how different entities used in a database are connected.
Definition of a database.
The stored schema of a database.
A set of rules that protects a database from errors during a transaction.
A device for connecting multiple network devices in one segment.
A device for connectiong multiple network devices and multiple segments.
A network arrangement where all computers are equal.
A private data resource using the same technology as the internet, such as browsers and protocols.
Local area network - confined to one location.
Wide areas network - covers large geographical area.
A set of rules or standards the control communication between devices.
A human readable name for a resource on a network. It is changed to a numerical IP address by a DNS server.
A number that identifies a device on a TCP/IP network.
Automatic switching to a backup computer system in the even of a system failure.
An item on a web page that directs the user to another location when clicked.
A store of information about devices on a network.
Reduction in file size to reduce download times and storage requirements.
A method of describing an algorithm using structured English close to programming language.
A diagrammatic method of showing the structure and data flow to define a problem and its solution.
A flow chart symbol that defines any processing to be completed at that stage.
A flow diagram symbol used to show a decision stage, may be 'yes' or 'no' or multiple values.
A method of using data to check that a flow chart covers all possibilities correctly.
A program to convert high-level or assembly-level commands into machine code.
The program written by the end user in a high-level language before it is converted to machine code.
The machine code produced by a compiler.
Integrated development environment (IDE)
Resources supplied with high-level languages to help the programmer.
Text area used to enter code in an IDE.
System to warn of errors in the code and potential problems.
Run time environment
Software to support the execution of programs.
System that tracks variables, modules and comments for maintenance for purposes.
A list of instructions to be carried out in order, one after the other
The pathway through a program is selected by using a condition to decide on what instructions to execute next.
Structures inside other structures.
Iteration or repetition
A group of instructions is executed repeatedly until a condition is met.
Whole number, positive or negative, with no decimal or fractional part.
A number that can have decimal or fractional parts.
A value that can only be true or false.
A sinlge alphabetic or numeric character.
A string or alphabetic and/or numeric characters.
A lable referring to a location in memory containing a value that can be accessed or changed by a program.
A lable referring to a location in memory containing a value that can be accessed but not changed by a program.
Identifying a variable or constant or array to a program so that memory space can be allocated.
Setting the value of a variable.
A logical, arithmetic or comparison operator used by the program.
Comparing the values of two items and returning TRUE or FALSE depending upon the result of that comparison.
Store data on a suitable media.
The rules of a language are broken by the program.
The logical structure of the program produces unexpected results.
Data used in testing that represents normal data that could be expected.
Data that is at the extreme limit of valid or invalid to check boundary conditions.
Data used to test a program that should be rejected because it is 'out of range'.
Data that would not normally be expected such as the wrong data type.
Uses the ASCII value to look up the character associated with a particular number.
Combining two strings into a single string.
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