[1] Analog Computer :
The computer which gives answer based on measure is called Analog computer. it was introduced in 1936. This is a machine which uses and gets same electric signal as system to be studied.
[2] Digital Computer :
Modern computer works on principle of digital signals. In this type of computers, any instruction or information is stored in the form of binary i.e. sequence of digital 0 and 1. Here it is considers that 0 means Off and 1 is On. Computer in which calculation can be done using particular digit is called Digital Computer.
It can be divided into four classes according to size.
Micro Computer : Micro computer is an invention of fourth generation computers. Its invention is the result of foundation of VLSI technology. In this type of computer, its central processing unit (CPU) is in the form of only single integrated circuit(IC) Which is called Micro processor.
due to this, size of this computer is very much reduced. That is why it can be put on a small writing table. There are so many diversities in this type of computer. These diversities are based upon its work efficiency like PC, PC-XT, PC-AT workstation and diversities are due to its size. This type of computers is used in school, college, computer center etc.
Classes of computers : https://en.wikipedia.org/wiki/Classes_of_computers