At a very elementary level, computers are broadly classified into three subcategories. They are analog, digital, and hybrid computers.
Digital and Analog computers have some core differences in their working principles. Analog computers may use mechanical or electrical characteristics in order to simplify or solve a problem. The first generation of computers developed used to be analog computers. They used capacitors, resistors, and vacuum tubes as the prime components. Traditional washing machines, energy meters, and digital meters are some examples of analog computers.
The term Analog Computers still does not strike a chord with people in general. They are the basic devices that resolve complicated problems. In analog computers, variation in a physical quantity measures the variation in a process (voltage, current or pressure).
An example of analog computation
The device used for measuring the water level in a tank must be pressure sensitive. Such applications hence use a piezoelectric crystal or a strain gauge.
Water pressure yields an approximation of the water level in the tank. The strain gauge transforms the signal into a proportional voltage signal. A voltmeter may further be used to know the change in voltage with the water pressure or the amount of water in a tank.
A few of the industries wherein analog computers find maximum applications include power plants, flight simulators, and chemical process plants.
Digital computers, on the other hand, encode a scenario from real life. Variable voltage levels across components help accomplish the same. Modern computers and scanners, and digital watches are some of the prime examples of digital computers.
Digital computers have higher accuracy levels as compared to analog computers. The accuracy of individual devices does not affect the accuracy of the system. This is because fixed voltage levels represent binary numbers. ISs, transistors and electric switches vastly comprise the circuitry.
But accuracy of analog computers, on the other hand, is subject to the individual accuracy of components within the analog computers. Analog computers, however, perform computations in real-time.
Calculations in digital computers used to involve significant delays in earlier days. Calculations in a sequential format lead to these delays. Digital computers are now a more advanced version of analog computers. More and more technologies are digitizing by the day because of the accuracy provided by digitization.
Instead of a physical quantity, digital computers operate using digital signals. Variables and continuous processes are encoded into discrete states. They are expressed as a group of numbers. Binary numbers express the states and perform the calculations as well.
A number of small electrical switches make the circuitry in digital computers. The switches can exist in two possible states, 1 for ON and 0 for OFF.
An example of digital computation
If one wants to create a water level indicator using a digital computer, then instead of an analog pressure sensor, one would use four different sensors. We place the sensors are placed at varying vertical levels in the water tank. When the water level rises in the water tank, the sensors will get activated.
Analog computers are nowadays rarer than they used to be earlier. One of the examples that exemplify the same is digital weighing machines. Digital computers are taking over the functionality of analog computers. Over the years, digital computers have overcome their limitations of slow speed and are now faster as compared to analog computers. The working mechanism of analog computers makes them slower in comparison.
While a mercury thermometer is an example of an analog computer, a digital thermometer is an example of a digital computer. Digital computers are also preferable, owing to their large memory and a user-friendly interface.