The First question comes here is What is Electronics -----
Electronics is science or computer science which deals with control of electric energy, energy in which the electrons have some fundamental roles. Electronics deals with electrical circuits such as resistors,capacitors, inductors, diodes and transistors that involve active electrical components and associated passive electrical components and interconnection technologies.
In early time vacuum tubes were used for technology. They were bulky in size. But today because of the tremendous progress in semiconductor technology, it became possible to fabricate thousands of components like diodes, transistors, resistors, and capacitors on tiny chips of silicon.
This made possible integration, which is the fabrication of complete circuits on a small silicon chip. The resulting devices are popularly known as ICs (Integrated circuits). ICs have significant advantages over discrete circuits as far size, weight, power consumption, cost, speed of operation, and reliability are concerned.
A large number of circuits can be fabricated on a single chip, requiring processes that are essentially similar to those for discrete transistors resulting in a considerable savings in size and cost. With the developments in semiconductor technology there has been a steady improvement in reliability, production yields, packaging density, and speed of operation.
In fact, the number of components per chip has doubled every year since 1959, when the planar technology for the manufacture of transistors was introduced. These developments have made possible electronic calculators, wrist watches, microcomputers, etc. on single chip of a few millimeter square sizes. Intel’s 8086 a 16-bit microprocessor introduced in 1978 contains about 29,000 transistors on a chip of about 6*6 mm2 size and the Pentium II introduced in may 1997 consists of about 7.5 million transistors.
All The major part of computer hardware comes under Digital Electronics These are
2. Logical gates with Truth table, Logical CIrcuit
7. Flip-Flop ... etc