There are three basic kinds of computers. This is based on the hardware structure and the way physical quantities are represented in a computer. The following are the three types.
Analog, Digital and Hybrid Computer
Analog computers are used to process analog data. Analog data is of continuous nature and is not discrete or separate. Such type of data includes temperature, pressure, speed weight, voltage, depth, etc. These quantities are continuous and have an infinite variety of values.
It measures continuous changes in some physical quantity e.g. The Speedometer of a car measures speed, the change of temperature
is measured by a Thermometer, the weight is measured by the Weights machine. These computers are ideal in situations where data can be accepted directly from measuring instruments without having to convert it into numbers or codes.
Analog computers are the first computers being developed and provided the basis for the development of modern digital computers. Analog computers are widely used for certain specialized engineering and scientific applications, for the calculation and measurement of analog quantities. They are frequently used to control processes such as those found in oil refineries where flow and temperature measurements are important. They are used for example in papermaking and in the chemical industry. Analog computers do not require any storage capability because they measure and compare quantities in a single operation. Output from an analog computer is generally in the form of readings on a series of dials (Speedometer of a car) or a graph on the strip chart.
A Digital Computer, as its name implies, works with digits to represent numerals, letters, or other special symbols. Digital Computers operate on inputs that are ON-OFF type and their output is also in the form of an ON-OFF signal. Normally, an ON is represented by a 1 and an OFF is represented by a 0. So we can say that digital computers process information which is based on the presence or the absence of an electrical charge or we prefer to say a binary 1 or 0.
A digital computer can be used to process numeric as well as non-numeric data. It can perform arithmetic operations like addition, subtraction, multiplication and division, and also logical operations. Most of the computers available today are digital computers. The most common examples of digital computers are accounting machines and calculators.
The results of digital computers are more accurate than the results of analog computers. Analog computers are faster than digital. Analog computers lack memory whereas digital computers store information. We can say that digital computers count and analog computers measure.
A hybrid is a combination of digital and analog computers. It combines the best features of both types of computers, i-e. It has the speed of an analog computer and the memory and accuracy of a digital computer. Hybrid computers are used mainly in specialized applications where both kinds of data need to be processed. Therefore, they help the user, to process both continuous and discrete data. For example, a petrol pump contains a processor that converts fuel flow measurements into quantity and price values. In the hospital Intensive Care Unit (ICU), an analog device is used which measures a patient’s blood pressure and temperature, etc, which are then converted and displayed in the form of digits. Hybrid computers for example are used for scientific calculations, in defense and radar systems.
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