Differences in certain computer characteristics have led to the development of major computer classifications based on the type of electronic signal and memory size.
Types of computers based on electronic signal
Computers, in general are of three types as per the electronic signal
(i) Analog Computers
(ii) Digital Computers
(iii) Hybrid Computers
An analog computer operates on inputs of continuously varying electrical voltages. An example of the use of an electronic analog computer is that of controlling a flight simulator for training pilots. The computer responds to the cockpit simulator control movements made by the pilot and makes physical changes in the environment so that the pilot feels as if he is controlling an actual aeroplane. Analog computers are used mainly in scientific design and production environments. Each one has to be constructed to do a specific job and will respond very quickly to changes in the measurement of inputs.
In digital computers, mathematical expressions are represented as binary digits (0 and 1) and all operations are done using these digits at a very high rate. It means that the computer operates on electrical inputs that have only two states, ON and OFF. These computers are widely used in commercial and control systems. Now a days when we use the word computer, we mostly refer to a digital computer.
Hybrid computers are computers with combined features of both digital and analog type. Desirable features of analog and digital machines can be combined to create a Hybrid Computer. This type of computer operates by counting as well as by measuring. In other words, the output can be either in the form of numbers or required units of measurement, e.g., an analog device measures patient’s heart beat (ECG). These measures will be converted into digital form and a digital device checks for any abnormality. Further, we can also input digital data like your marks and get digital results like the result of your class. Another example is a Modem. (which converts the digital signals into analog, carry it along the line and at the
receiving end again changes it back into digital signal).