Hardware |
A computer system will input, process and then output data. A computer system consists of the computer and other hardware devices that are used with the computer. A hardware device is an electronic or electro-mechanical device such as a keyboard or monitor which forms part of a computer system.
The diagrams below show one simple and one more complicated computer system.
The devices connected to the computer can be divided up into three different classes :
| Input Devices | An input device takes data from the outside world and sends it to the computer. e.g. keyboard, mouse. |
| Output Devices | An output device takes data from the computer and converts this into information in a form which is normally understandable by humans. e.g. printer, VDU. |
| Input / Output (I/O) Devices | Data flows in both directions between the computer and an I/O device. Most I/O devices are used for storage e.g. hard disk drive or communications e.g. modem. Others include MIDI keyboards. |
Some devices such as disk drives, modems and CD-ROM drives are now built into the same box as the computer. This helps to keep computers tidy. Devices connected to a computer are often known as peripherals.
Computer hardware is not very useful by itself. The hardware needs to be told what to do. A computer program contains instructions to tell the computer hardware what to do to carry out a particular task. Computer programs are produced using a programming language. Computer programs are also known as software. The most important piece of computer software that a computer system must have to function is an operating system. Other useful pieces of computer software include word processors, spreadsheets and databases.
There are separate articles on the many different items that could be included in a computer system. As a starting point, here is a brief list of the components that you would expect to find inside a typical computer :
Computer systems are designed to be flexible. It is usually possible to expand the capabilites of a computer by replacing or upgrading internal components or connecting extra devices externally. External devices are connected to a computer using sockets known as ports.
There are three main types of computer. They are :
Microcomputers (also known as PCs) are the smallest and cheapest of these and are used at home, in schools and in some businesses. Most PCs contain just one microprocessor.
Mainframe computers are the most powerful computers. A mainframe computer may contain several microprocessors. Computers which contain more than one processor are capable of doing more than one thing at a time and are described as being capable of parallel processing. A single mainframe computer can be used by hundreds of people at once. Each user has his own terminal that is connected to the mainframe. Mainframe computers are usually kept in a special cooled, clean computer room. Today many businesses are getting rid of their mainframe computers and replacing them with networks of smaller microcomputers.
Minicomputers were medium-sized computers that were more powerful than microcomputers but not as powerful as mainframes. Minicomputers where phased out in the 1990s as microcomputers became more powerful.
This table makes some comparisons between the different types of computer :
| Comparisons of Computer Types | |||
| Comparison | Microcomputer | Minicomputer | Mainframe |
| Where Used | Home, small business, on a network in a larger business. | Medium sized business. e.g. supermarket, traffic control system. | Large businesses, universities. |
| Number of Users | 1 | 1-20 | Hundreds |
| Cost | £200 - £10,000 | Not Available | £150,000+ |
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A Supercomputer is a very fast mainframe which may contain many hundreds of microprocessors.
A microcomputer is a computer that is based around a microprocessor. The most common type of microcomputer is the Desktop but there are a number of other types as well :
| Type | Description |
| Desktop | The Desktop is the most common type of microcomputer. Desktop PCs are quite bulky and are usually connected to several external peripherals such as a mouse, keyboard and printer. Desktop machines are not very portable but can be upgraded fairly easily to enhance their capabilities. |
| Laptop | A laptop is a small microcomputer which is portable. Laptops are battery powered and incorporate all of the important components of a computer system such as keyboard and VDU into one unit. Most laptops are about the size of an A4 folder. Laptops are also known as notebooks. |
| Palmtop or PDA | A Palmtop or Personal Digital Assistant (PDA) is a very small microcomputer which is designed to be handheld and fit in a jacket pocket. Palmtops/PDAs can carry out general purpose computing tasks and are usually supplied with software such as a diary and address book to help the owner organise his life. |
| Games Console | A games console is a microcomputer that has been specifically designed to play computer games. It will probably incorporate a CD-ROM or DVD drive to load the games from and be supplied with an input device consisting of a joystick and small keypad. |
| Embedded System | An embedded system is a computer system which forms part of a larger device such as a washing machine, video recorder or car. Embedded systems are usually suited to just one specific task and can not be connected to general purpose peripherals such as keyboards and printers. Embedded systems are often used in control applications to perform real time processing. |
GCSE ICT Companion 04 - (C) P Meakin 2004