Generations of Computer

Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices.

The various generations of computers an listed below :
(i) First Generation (1946-1954) : In 1946 there was no 'best' way of storing instructions and data in a computer memory . There were four competing technologies for providing computer memory: electrostatic storage tubes, acoustic delay lines ( mercury or nickel), magnetic drums (and disks?), and magnetic core storage.

Limitations of First Generation Computer
Followings are the major drawbacks of First generation computers.
1. They used valves or vacuum tubes as their main electronic component.
2. They were large in size, slow in processing and had less storage capacity.
3. They consumed lots of electricity and produced lots of heat.
4. Their computing capabilities were limited.
5. They were not so accurate and reliable.
6. They used machine level language for programming.
7. They were very expensive.
Example: ENIAC, UNIVAC, IBM 650 etc

(ii) Second Generation (1955-1964) : The second-generation computer used transistors for CPU components & ferrite cores for main memory &magnetic disks for secondary memory. They used high-level languages such as FORTRAN (1956), ALGOL (1960) & COBOL (1960 - 1961) . I/O processor was included to control I/O operations.

Features:
1. Transistors were used instead of Vacuum Tube.
2. Processing speed is faster than First Generation Computers (Micro Second)
3. Smaller in Size (51 square feet)
4. The input and output devices were faster.
Example: IBM 1400 and 7000 Series, Control Data 3600 etc.

(iii) Third Generation (1964-1977) : By the development of a small chip consisting of the capacity of the 300 transistors. These ICs are popularly known as Chips . A single IC has many transistors, registers and capacitors built on a single thin slice of silicon.

Features:
1. They used Integrated Circuit (IC) chips in place of the transistors.
2. Semi conductor memory devices were used.
3. The size was greatly reduced, the speed of processing was high, they were more accurate and reliable.
4. Large Scale Integration (LSI) and Very Large Scale Integration (VLSI) were also developed.
5. The mini computers were introduced in this generation.
6. They used high level language for programming.
Example: IBM 360, IBM 370 etc.

(iv) Fourth Generation : An IC containing about 100 components is called LSI (Large Scale Integration) and the one, which has more than 1000 such components, is called as VLSI (Very Large Scale Integration) .

Features:
1. They used Microprocessor (VLSI) as their main switching element.
2. They are also called as micro computers or personal computers.
3. Their size varies from desktop to laptop or palmtop.
4. They have very high speed of processing; they are 100% accurate, reliable, diligent and versatile.
5. They have very large storage capacity.
Example: IBM PC, Apple-Macintosh etc.

(v) Fifth Generation (1991- continued) : 5th generation computers use ULSI (Ultra-Large Scale Integration) chips. Millions of transistors are placed in a single IC in ULSI chips. 64 bit microprocessors have been developed during this period. Data flow & EPIC architecture of these processors have been developed. RISC & CISC, both types of designs are used in modern processors. Memory chips and flash memory up to 1 GB, hard disks up to 600 GB & optical disks up to 50 GB have been developed. fifth generation digital computer will be Artificial intelligence.