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# Glossary

Computer
  A machine that manipulates data following a list of instructions that have been programmed into it.

Computer program
  The list of instructions the computer follows to process input and produce output.

Input device
  A component that can function both as an input and as an output device.

Internet
  A global network of connected networks.

Output device
  Components that present data from a processor.

Smart devices
  Devices that can communicate directly with other devices.

World Wide Web
  A global collection of resources accessible over the internet.

Binary
  A system limited to having just two values.

Computer bus
  The internal data connections across the input and output subsystems and the secondary memory subsystem to the computer’s processor and main memory.

Computer system
  Formally a processor and its associated devices to make a usable ‘system’, but often the complete system, is referred to as a ‘computer’.

Digital
  In our context, it means systems using discrete rather than continuous values. In the larger contest of computers in society, there is also the social and marketing use of ‘digital’, where it represents a way of engaging with people.

Embedded computer system
  Specialised processors acting as controllers for devices such as washing machines and microwave ovens.

Hard disk
  A form of secondary memory consisting of one or more rigid magnetic disks rotating about a central axle. Also known as a hard drive.

Hardware
  The physical components of a computer or computer system.

Input-output device
  A component that can function both as an input and as an output device.

Input-output subsystem
  The components of a computer system responsible for the retrieving, transforming and presenting the data used by a processor, functioning as both an input subsystem and an output subsystem.

Input subsystem
  The components of a computer system responsible for the entry of external data and its transformation into a form the processor can use.

Main memory
  Where a processor stores instructions and associated data for execution.

Microprocessor
  Was introduced when processors were first made on a single silicon chip, with the prefix ‘micro’ emphasising their small size

Output subsystem
  The components of a computer system responsible for the transforming and presenting the data used by a processor into a form for use outside the computer system.

Secondary memory
  Holds programs and data that will persist after the computer is switched off.

Secondary memory subsystem
  The components of a computer system that prepare data for and retrieve data from secondary storage.

Software
  The program, or collection of programs, that enable a computer to carry out its tasks.

ASCII
  American Standard Code for Information Interchange, pronounced ‘askee’, a method of encoding text in binary digits.

binary code
  The representation of an item of data using only two values

bit
  A binary digit, which can be either one or zero.

byte
  A group of eight bits.

Embedded computer
  Computers that are part of another device dedicated to delivering one task.

Application software
  The program that enables a computer to perform certain tasks.

Embedded computer
  Computers that are part of another device dedicated to delivering one task.

Flowchart
  A diagram showing a sequence of actions using specifically shaped symbols.

Operating system
  Software that controls the resources and software using a computer.

Internet
  A global network of connected networks.

Internet of things
  Devices exchanging data directly with each other over the internet.

Local Area Network (LAN)
  Connects devices within a limited in one network.

Wide Area Network (WAN)
  Connects LANs into a larger network.

World Wide Web
  A global collection of resources accessible over the internet.

Calm technology
  When technology recedes into the background of our lives so that it does not impinge on us when we interact with it.

Green computing
  Is the environmentally responsible and eco-friendly use of computers and their resources.

Pervasive computers
  Embedded microprocessors in day-to-day objects, allowing them to communicate data, often used interchangeably with ubiquitous computing.

Ubiquitous computing
  Or ‘ubicomp’ describes when computing is anytime and everywhere, in contrast to desktop computing.

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OpenLearn - An introduction to computers and computer systems
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