DEFINITION DIGITAL COMPUTER:
A digital computer is machine that stores data in a numerical format and performs operations on that data using mathematical manipulation. This type of computer typically includes some sort of device to store information, some method for input and output of data, and components that allow mathematical operations to be performed on stored data. Digital computers are almost always electronic but do not necessarily need to be so.
There are two main methods of modeling the world with a computing machine. Analog computers use some physical phenomenon, such as electrical voltage, to model a different phenome,mnon, and perform operations by directly modifying the stored data. A digital computer, however, stogres all data as numbers and performs operations on that data arithmetically. Most computers use binary numbers to store data, as the ones and zeros that make up these numbers are easily represented with simple on-off electrical states.
Computers based on analog principles have advantages in some specialized areas, such as their ability to continuously model an equation. A digital computer, however, has the advantage of being easily programmable. This means that they can process many different sets of instructions without being physically reconfigured.

THE HISTORY OF DIGITAL COMPUTER:
First Generation (1940-1956):
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.
First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape,