Title: Understand what a personal computer is
Course: Module 1, Concepts of Information and Communication Technology (ICT)

What types of computer are there?

The type of computer most often used in the office is known as a Personal Computer, or 'PC'.
PCs are also frequently used in the home.
However, not all the computers that people use are PCs.
For example a bank’s automatic cash dispenser is a computer but it is not a PC.

This section will discuss the following types of computers:
- Mainframes
- Personal Computers
- Laptops
- Tablet PCs

Mainframes

- A mainframe is a centralised computer capable of serving large numbers of users at the same time. Mainframes tend to be used less since the speed of desktop PCs has increased and the cost decreased. It is far more cost effective for a company to buy standard PCs that are networked together than a single mainframe nowadays.

- Users do not sit down in front of the mainframe computer itself. They connect to it using another smaller computer or a dumb terminal. (A dumb terminal usually consists of a keyboard and screen, and simply enables a user to connect to and use the mainframe computer. A dumb terminal does not process or store any data itself, ie it is not intelligent.)

- Because mainframes need to process and store information for many different users at once, they require much more processing power and storage capacity than other computers, i.e. they need to be faster and have more memory. The result is that they tend to be very expensive.

- Mainframes are often used by large corporate and government data processing departments, where many users need access to large amounts of information. Mainframes allow this information to be centrally stored and controlled. They also offer more power and require less maintenance than clusters of smaller computers.

Every time you use an automatic cash dispenser at a bank, you are using a small computer (the cash dispenser) to access a central mainframe computer that stores information regarding your account.

Desktop Personal Computers (PCs)

- As we mentioned earlier, the PC is the most common type of computer used not only for commercial but also for personal use — hence the term 'Personal Computer'.

- Usually, only one user accesses a PC at any one time. The user sits in front of the PC and works with it directly rather than connecting to it using another computer or a dumb terminal.

- Because a PC only has to serve one user at a time, it requires far less processing power and storage capacity than either a mainframe or a minicomputer. This, in turn, means a PC is far less expensive.

- All PCs have a similar basic structure but are produced by a large number of manufacturers with different specifications and components.

- In the late 80s and early 90s many PCs were known as IBM compatible PCs. This was because when PCs were first produced they were not all able to use the same software formats. Now nearly all PCs are compatible with the IBM standard and the term is less commonly used.

- PCs are often used as intelligent terminals to connect to a mainframe or a minicomputer. The advantage of this over using dumb terminals is that users can process and store some information locally, so that the burden on the central computer is reduced.

- The main reason why the PC is so popular is that it is a versatile tool that can be used for a wide range of applications.

Desktop networked computers

- A Network Computer (NC) can be thought of as a low-cost version of the PC.

- It is designed to connect to and be managed by a central computer (e.g. a mainframe or a minicomputer). Each time the Network Computer is switched on, it retrieves the latest version of the software it needs from the central computer. This means that components used to install and upgrade software (such as a diskette drive or a CDROM drive) are not required.

- Network Computers tend to have slightly less processing power and storage capacity than PCs. This, coupled with the lack of other components, makes them substantially less expensive. However, it should be remembered that a Network Computer is of no use unless it is connected to a central computer whereas a PC can operate on its own.

- Network Computers tend to be used in call centres, help desks and data processing departments where users don’t require the flexibility of a PC, but need to access centralised software and information. The main advantage is that when software needs to be changed, it only needs changing on the central computer, not the individual Network Computers themselves.

Laptops

- A laptop computer is a portable computer designed to fit inside a briefcase — many laptops are approximately 12” (30 cm) wide by 9” (23 cm) deep by 2” (5 cm) high, although sizes do vary.

- Modern laptops have most of the features and components available on PCs, and offer the same level of flexibility in performing a wide range of tasks.

However, the size of a laptop makes it more difficult and costly to develop, so laptops tend to be more expensive, and generally have less processing power and storage capacity than desktop PCs.

- A laptop has a built-in screen and keyboard. This is one of the main reasons why a laptop is so portable. The screen is usually a Liquid Crystal Display (LCD) less than 1 cm thick. The screen is usually the most expensive part of a laptop. It is increasingly common to find laptops with cameras and microphones in-built.

- Laptops tend to be used by people who do a lot of travelling in their job, and need to be able to process and store information wherever they are (and whether or not they have a power source available). Examples would be sales representatives, consultants and support engineers who need to travel to different sites. These days many people have laptops just because of their convenience.

Tablet PC

- A Tablet PC is a laptop or slate-shaped mobile computer, equipped with a touchscreen or graphics tablet/screen hybrid to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse.

- This form factor offers a more mobile way to interact with a computer.

- Tablet PCs are often used where normal notebooks are impractical or unwieldy, or do not provide the required functionality.

Question about computers

Which of the following is not a computer?

- TV remote controller
Feedback: Correct.
- Desktop
- PDA
- Laptop