A computer is one of the greatest inventions of man and it has seen many changes in functions, memory space, size and portability. The computer is an extraordinary machine because of its ability to store and process a massive amount of information. It is used to perform various technical tasks or even help create other gadgets. The different types of computers are in use today due to the continuing advances in computing technology. Computers are broadly divided into three groups on the basis of computing techniques used. The types of computer are:
- Analog Computer
- Digital Computer
- Hybrid Computer
Analog is derived from the Greek word which means similar. The similarities between any two quantities are measured in the form of electrical voltage or current. Analog refers to numerical values that have a continuous range, Thus, analog computer is the one work on numerical data represented some physical quantity (e.g. rotation displacement) or electrical quantity (e.g. voltage or charge) which varies continuously. The display is also continuous. The output is designed to usually in the form of graphs.
Analog computer is a special purpose computer i.e. specific to a particular task. They are generally used for process control in industries. This computer is faster in speed because calculation are performed in parallel but its accuracy is poor than digital computer. A popular analog device used in the 20th century was the Slide Rule in which numbers were expressed as distances.
Digital computer is designed to process data in numerical form. Its circuits perform directly the mathematical operations of addition, subtraction, multiplication, and division. The numbers operated on by a digital computer are expressed in the binary system. By manipulating combinations of binary digits ( binary code), it can perform mathematical calculations, organize and analyse data, control industrial and other processes, and simulate dynamic systems such as global weather patterns. These computers can be further classified according to their difference in size, cost, application areas and computing power. They are as follows:
- Mainframe computers
Supercomputer is a computer that is the fastest around. It is also very powerful, expensive and can process large amounts of information. Super computers have a large memory and high processing speed. They can process up to billion operations per second. These computers have multiple Central Processing Unit that can process multiple instructions at a time, known as parallel processing. These computers are a national resource. Such computers are typically used for number crunching including scientific simulations, (animated) graphics, analysis of geological data (e.g. in petrochemical prospecting), structural analysis, computational fluid dynamics, physics, chemistry, electronic design, nuclear energy research and meteorology.
- Cray Titan
- NUDT Tianhe-2
Mainframe computer is a high-performance computer used for large-scale computing purposes that require greater availability and security. These computers are large computers, comprising a number of free-standing units. Mainframes are housed in specially designed air-conditioned rooms. Mainframes are very powerful with large backing storage, and can support a number of terminals running concurrently serving many hundreds users without degrading its performance. Hence, it is also called as a “central host computer”. They are used in bank, government departments and big companies as their main computer.
The two mainframe computers brought in Nepal for the population census of 2028 and 2038 B.S was done with IBM-1401 and ICL 2950/10 respectively.
Minicomputer is a type of computer that possesses most of the features and capabilities of a large computer but is smaller in physical size. It is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems (mainframe computers) and the smallest single-user systems (microcomputers or personal computers). Minicomputers were primarily designed for business applications and services that require the performance and efficiency of mainframe computers. Minicomputers are generally used as mid-range servers, where they can operate mid-sized software applications and support numerous users simultaneously. The examples of minicomputers are the AS/400, the PRIME series, the AP-3, Olivetti’s Audit 7 and the Interdata 8/32.
A computer based on a single-chip microprocessor is known as mico-computer. It is relatively cheap, and permit fewer peripheral device to be connected. It is usually connected with a keyboard for input and incorporate a Visual Display Unit on which output may be displayed. It is usually designed to be operated by one person at a time.
Microcomputers are also called personal computer. Microcomputer are general purpose computers which can do a variety of jobs. Microcomputers are commonly used in offices and homes and many are used as workstations. The two popular sub-categories of microcomputer are:
Desktop computer is a computer designed to fit comfortably on top of a desk, typically with the monitor sitting on top of the computer. Desktop model computers are broad and low, whereas tower model computers are narrow and tall. Because of their shape, desktop model computers are generally limited to three internal mass storage devices.
A portable computer is a computer that is designed to be moved from one place to another and includes a display and keyboard. Portable computers, by their nature, are generally microcomputers. Portable computers, because of their size, are also commonly known as ‘Lunchbox’ or ‘Luggable computers. They can also be called as Portable Workstation’ or Portable PC. “They are available in two forms, namely, laptops and palmtops.
A laptop is a portable computer that can sit on your lap. It can be powered by rechargeable batteries or plugged into an electricity supply. The main advantage of this computer is that one can use this computer anywhere and at anytime, specially when one is travelling.
A palmtop computer is so small that it can fit on the palm of your hand. A stylus is often used to enter information. It uses small cards to store programs and data. It has to be plugged into a main computer for other uses. It is generally used for simple applications such as personal organizations and note taking. It can also be attached to mobile phones enabling it to receive and send e-mail.
Hybrid computers are computers that exhibit features of analog computers and digital computers. The digital component normally serves as the controller and provides logical operations, while the analog component normally serves as a solver of differential equations. The HRS-100 was a prominent example in the 1970s. One example of a place you may find a hybrid computer is in the medical field or centres. This helps lessen the overall time needed for data processing. Another example of computer people are calling hybrid is a laptop mixed with a tablet. This means that a person can use a laptop, but if they need to take it someplace, they have the ability to remove it from the keyboard and use it as a tablet.
Read more: Computer Fundamentals
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