a computer

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A computer is a collection of devices for storing and processing information. It contains things like a CPU, disk drive and interface.

Many computers are used to make the LIC work. A computer is part of the physical presence of the LIC. Each computer provides one or more hosts which provide one or more Internet services.

what it is

A computer is a box of electronic bits that can store information and follow instructions to tweak that information. On the inside are devices full of millions of switches that make enormously long strings of zeros and ones. On the outside are devices that translate those zeroes and ones into something useful like music, pictures and language.

A computer is part hardware and part software. The hardware is machinery: the part you can touch. It includes things for storing information like disk drives, things for putting information in like a keyboard and things for getting information out like a display screen. The software is the information and the processing instructions: the bit you just have to believe in because it has practically no physical presence. The computer software controls the computer hardware.

Computers can also be split into two groups according to whether they are special purpose or general synthesizerpurpose.

a specialised computer

A specialised computer has hardware and software dedicated to providing one service. It is usually smaller, faster and cheaper than a general purpose computer. It is not flexible in what it does so the software can be highly tuned, as opposed to a general purpose PC where the operating system must carry extra code ready for anything. This single-minded purpose makes a specialised computer easy to install and maintain.

Some specialised computers are called appliances to make customers think of a major appliance in the kitchen such as a dishwasher or a microwave. The association with dirty plates and ready-meals makes good marketing sense. An appliance is something you connect up, plug in and hey presto, it works. Many network computers such as switches and routers are appliances.

The confusion in computer naming is strongest with network computers. People refer to network computers as network devices (because they use electricity), network machines (because they are man-made), network boxes (because no-one sells computers in bags) or network kit (because they can't think of any more accurate term).

a general purpose computer

A general purpose computer provides a range of devices to cover most requirements, and provides sockets to plug in more devices. This type of computer is the foundation used by the dozens of popular operating systems and many thousands of applications out there in the world of information technology.

People often pigeonhole general purpose computers according to a few criteria.

  • size,
  • architecture
  • processor, also known as a CPU (Central Processing Unit).

Size is only helpful to describe what a computer costs rather than what it can do. In terms of processing power this decade's mainframe is the next decade's PC.

sizes of computer
type what it is description
PDA (Personal Digital Assistant) A stripped down PC small enough to fit in a trouser pocket. A tiny general purpose computer usually used for keeping track of a calendar, e-mail and an address book. Also called a pocket PC.
PC (Personal Computer) a small general purpose computer with one of everything needed to make it work on its own: keyboard, CPU, mouse, screen, disk and so on. The most popular type of computer. They are everywhere. PC is associated with IBM's design of PC but it also covers MacIntosh and other brands. Also called a desktop PC.
workstation a beefed up PC: bigger screen, more memory, bigger price tag. Used in niche markets such as graphics rendering. As PCs become more powerful the workstation market becomes smaller.
minicomputer a stripped down mainframe. This is a leftover category from the days when PCs were rubbish and mainframes cost more than small countries.
mainframe a multi-user computer that can be used by hundreds or even thousands of people at the same time. Decades ago this was the only type of multi-user computer. A mainframe costs more than a house, is bigger than a car and costs more to maintain than a teenage daughter.
supercomputer a beefed up mainframe. The biggest computers in the world, used for things like weather prediction. The old definition of a supercomputer now includes PCs.

The design and construction of a computer is called its architecture. Different general purpose computers are built in different ways by different manufacturers. By far the most common type of general purpose computer is an IBM PC (Personal Computer).

The processor in an IBM PC is an Intel x86. This is actually a category that covers processors named 80386, 80486 and Pentium. Other popular processors include the Dec Alpha, Sun Sparc and Motorola PowerPC. Just to confuse things, as is normal in computerland, the type of processor in the computer is also called its architecture.

what it isn't

The host is not the computer. A host is a location on a network, used to describe where Internet services are located. The computer's operating system provides the host details.

where it is

The LIC is full of small cheap general purpose computers split into several groups. Each group has one job to do, such as providing a customer service or protecting the network.

No computer is a multitasking monster. It does not have solely one job to do because there are support tasks that the computer's software has to take care of such as monitoring, maintenance and data backup. Ideally each computer would only have only one main job. This means the LIC is full of lots of small computers which gives some systems administrators box fatigue. They would rather have only one or two big computers doing lots of jobs.

The general idea is lots of network computers form the backbone of the LIC and lots of application computers are attached to them.


In 1834 Charles Babbage came up with the idea of the analytical engine. This had the basic features of a modern general purpose computer.

In World War Two the first electronic computers such as the Colossus model were created at Britain's Government Code and Cipher School (GC&CS) to break the Germans' Enigma codes.

In 1958 there were 2,500 computers in the USA. By 1963 there were 18,000.

In 1959 Jack Kilby patented the miniaturized electronic circuit and Robert Noyce patentd the silicon based integrated circuit. This was the start of using chips in computers.

In 1973 the first PC, named Alto, was created at Xerox PARC. It had a GUI, a mouse and another PARC invention with a big future, ethernet.

In 1976 Steve Jobs and Steve Wozniak created a PC called Apple I.

In 1981 IBM released their version of a PC. In 1983 the PC XT was released, costing $4,995.

In 1985 Intel released their first 32 bit CPU, the 80386DX.

In 1990 there were over 55,000,000 computers in the USA. By 1993 one in three households had a PC.