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iGCSE ICT notes 2.1
AO2.1 Types and components of computer systems
A. define hardware, giving examples
Hardware is a physical device / object / part of computer / equipment / component that you can touch.
For example, mouse / screen / monitor / keyboard.
B. define software, giving examples
The programs and other operating information used by a computer. It is computer instructions or data. It is also
anything which can be stored electronically.
For example, word / powerpoint / photoshop.
C. describe the difference between hardware and software
You can touch hardware, but not software. Software runs the hardware and tells it what to do. Without software,
hardware would be useless.
D. identify the main components of a general-purpose computer: central processing unit, main/internal memory
(including ROM and RAM), input devices, output devices and secondary/backing storage
see page 3
E. identify operating systems, including those which contain a graphical user interface, a command line interface
Operating systems enable users to communicate with computer systems. The general tasks for a typical operating
controlling the operation of the input, output and backing storage devices
supervising the loading, running and storage of applications programs
dealing with errors that occur in applications programs
maintaining security of the whole computer system
maintaining a computer log (which contains details of computer usage)
allowing communication between user and the computer system (user interface)
Computer users need to be able to communicate with the operating system this is called the `user interface'. There
are two main types of user interfaces: command line interfaces (CLIs) and graphical user interfaces (GUIs)
A command-line interface (CLI) is a means of interaction with a computer program where the user issues commands
to the program in the form of successive lines of text.
Command-line interfaces are still often preferred by more advanced computer users, as they often provide a more
concise and powerful means to control a program or operating system.
CLIs require a user to type in instructions in order to choose options from menus, open software etc. There are often a
number of commands that need to be typed in for example, to save or load a file. The user therefore has to learn a
number of commands just to carry out basic operations.
GUI'S allow the user to interact with a computer, for an example an MP3 or a gaming device using icons (pictures or
symbols) rather than typing in a number of devices. GUI uses a several versions of technology and devices to provide
user interface. One of the most common is windows icon menu and pointing device (WIMP) which was developed for
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GCSE ICT notes 2.1
use on personal computers. This uses a mouse to control a cursor, which then selects icons to run/open windows. Each
window contains an application and modern computer systems allow several windows. A windows manager looks
after the interaction between windows, the applications and windowing system (which handles the pointing devices
and the windowing system.)
F. identify different types of computer including Personal Computer or desktop, mainframe, laptop, palmtop and
Personal Digital Assistant
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