In Simpler words, the computer can be defined as the advanced electronic device that takes input(raw data), processes that input, gives some result to the user as output, and saves or stores that output and data. So, the computer can be divided into four major components: arithmetic unit.
- The input and output devices (I/O)
- Arithmetic logic unit (ALU),
- The control unit
- The memory unit, and
Generations of computer:
Generations of computers are focused on whether there have been significant technical advances in computers. Like use of vaccum tube in first generation of computer, transistors in second generations of computer, Integrated circuit and microprocessor in later computers. The following table shows the use of which technology in which generation of computer.
| S.N. | Genrations of computer | time period | technology used | examples |
| 1. | First generation computer | 1946-1959 | Vaccum tubes or thermionic valve machine. | ENIAC EDVAC UNIVAC IBM-701 IBM-750 |
| 2. | Second generation computer | 1959-1965 | transistors | IBM 1620 IBM 7094 CDC 1604 CDC 3600 UNIVAC1108 |
| 3. | Third generation computer | 1965-1971 | Integrated Circuits (ICs) | IBM-360 series Honeywell-6000 series PDP (Personal Data Processor) IBM-370/168 TDC-316 |
| 4. | Fourth-generation computer | 1971-1980 | Very Large Scale Integrated (VLSI) circuits | DEC 10 STAR 1000 PDP 11 CRAY-1(Super Computer) CRAY-X-MP(Super Computer) |
| 5. | Fifth generation computer | 1980-till date | ULSI (Ultra Large Scale Integration) technology | Desktop Laptop Notebook Ultrabook Chromebook |
Features of first generations of computer:
- Vacuum tubes were used as their main electronic components to make circuits.
2. Punch cards, paper tape, magnetic tape and magnetic drums were used.
3. First generation of computers used machine level or binary language and symbols.
4. Low memory space and very slow output are the characteristics of first generation of computer
5. The size of computer filled large space because of incredibly huge size and it is nearly impossible to move the computer from one place to another place (importable).
6. Huge electric power was needed to run the computer. So, consumption of electricity is very high.
7. It generated a lot of heat. It needed AC to decrease the temperature.
2. Features of second generations of computer:
- Transistors were used as their main electronic component