Classification of computers

On the basis of working principle, computer can be classified into three types:
a. digital computer
b. analog computer
c. hybrids computer

Digital computer
Digital computer is widely used these days. The ‘PCs’ that we used in our house and school is also the digital computer. Digital computer are so called because they worked on principle of binary digits (i.e. zero and ones)

The digital computer take input, store data and operating on the inputs in the digital fashion. Everything that digital computer inputs, processes, stores is a digital signal. The data and instruction we give to the digital computer are digital signals. All other device that a digital computer contains also either generates or input or stores the digital signals.
Hence, in short, the digital computers can be defined as, ‘the computer which operate with the digital signals.’

Analog computer
Analog (or analogue) computer are quite rare these days though they were found in past. The “sliding rule”, “differential analyzer”, etc. about which we study in the history of computers were the analog computer

Analog computer is still in used today in very special sectors, like scientific research.
The basis difference in analog and digital computer is the signal they used to operate the analog computer use the analog (continuous) signals varying according to the time.
An ideal analog computer can solve all the problems that can be solved by the digital computer. But, an analog computer must be made for the specific purposed. The analog computer made for one purpose cannot work for another purpose like digital computer can do. So the analog computer less versatile and less popular than the digital computers.

Hybrid computer
Hybrid computer are made to get the advantage of both the digital and analog computer. These computers can work both with digital signal and analog signals. More currency, the hybrid computer use analog signals for certain operation (like measure of temperature) and use digital signals for the other operation. These computers also have capacity to convert the analog signals to digital signals.
Such computers are used in hospital to measure heart function, temperature, etc. these are also used in other areas like scientific research aircraft industrial, etc. some popular hybrid computers are:
a. flight management computer (FMC)
b. Engine indicator and crew alert system (EICAS), etc.