Classification Of Computer

On the basis of size

The digital computers that are available nowadays vary in their sizes and types. The computers are classified into four categories based on their size:

Microcomputers: Microcomputers are small, less costly and single user digital computers which consist of CPU, input unit, output unit and storage unit along with software. Being alone machines, they can be connected together to create a network of computers that can be used by more than one user. IBM PC based on Pentium microprocessor and Apple Macintosh presents the examples. Microcomputers cover desktop computers, notebook computers or laptop, tablet computer, handheld computer, smartphones, and notebook.

1. Minicomputers: A minicomputer is a mid-range computer smaller than the mainframe computers. The technology and operating environment including the knowledge for it were similar to the mainframe. It is less expensive and occupies fewer office spaces. The mini computers are affordable. Universities, factories, research laboratories, corporate offices use them.
2. Mainframe Computers: Mainframe computers are multi programming, multi user, and high-performance computers. A mainframe is a large computer, a powerhouse with massive memory and extremely rapid processing power. The computers were very expensive and the computer knowledge was confined within few experts. Besides their use in a scientific and military application, major business applications are also processed.
3. Supercomputers: Supercomputers are highly sophisticated and powerful equipment capable of processing complex calculations rapidly. It is the fastest and largest computer available today. It has very large memory and very high-speed processing capabilities. It has been traditionally used in scientific and military work, but it is also used in forecasting natural disasters like earthquake, cyclone, weather change, tide, etc. Most supercomputers have the ability to recover automatically from failure, i.e. they have the capability of fault tolerance.

On the basis of data

Analog computer: An analog computer performs by setting up physical situations that are analogous to mathematical situations. It operates on data in the form of continuously variable physical quantities such as pressure, temperature, revolution, speed of sound or voltage. It is basically a measuring device or equipment. An automobile speedometer is a very good example that utilizes information on the analog form. It converts the turning rate of a shaft into numerical approximation speed and is displayed on a meter. Since analog data is acquired through a measuring process analog computers have the advantage to accept data directly from the measuring equipment’s without any conversion. This feature along with its ability to process data at high speeds makes these machines useful as controlling devices in oil references, paper and steel mills, military weapons system, etc.

Digital computer: Digital computer operates on discrete data (0 and 1). It operates by counting and calculation. The digital computers have the capability to handle alphabetical and numerical data with precision and speed makes them ideally suited for processing data. It is a general purpose computer. It can be reprogrammed. It can be operated by general users. Devices like a digital watch, digital speedometer, etc. are the examples of digital devices. IBM desktop PC, Dell laptop, Acer notebook are the examples of digital computers.

Hybrid computer: A computer system which combines the capability of analog and digital computers into one is known as a hybrid computer. Such capability is most significant in a situation where digital processing of data collected in analog form is desirable.A very widely used application is passenger check-in system at the airport. The weight of passenger baggage is captured by weighing machine and the data is transferred to check-in software to ascertain whether the baggage weight is under allowed limit or not and if it exceeds allowed weight the check-in application prints excess baggage bill for the passenger.

Classification of Micro-computer

Desktop Computer or Personal Computer (PC): It is the most general type of microcomputer. It is a stand-alone machine that can be put on the desk so known as the desktop. Visibly, it consists of three units: keyboard, monitor, and a CPU. It is not very expensive and is suitable for the user at home, small business units, and organizations. Apple, Microsoft, HP, Dell and Lenovo are some of the PC manufacturers.

Notebook Computers or Laptop: Further development of technology has been able to create an easily movable computer of the size of the notebook which stays quietly over a person’s lap having capabilities that of the desktop. It is aimed to meet the requirements of executives of the organization that needs to carry their tasks at home. The laptop usually incorporates all features of desktop computers. It consumes very less power and gets less heated. It operates with AC or DC power. It does not contain expansion slot. Laptops are difficult to upgrade.

Handheld Computer or Personal Digital Assistant (PDA): A portable computer that is small enough to be held in one’s hand is called handheld computer. It is designed to provide personal information manager functions like calendar, address book, memos, etc. Being extremely convenient to carry, these computers are widely used today. It accepts touch screen input, contains electronic writing pad and light sensitive electronic pen.

Reference

Ghishing, Er.Ashim. Computer Science. Kathmandu, Nepal: Benchmark , 2008.