Explain various Computer Generations in detail.

Semester :-1

Unit:-1

Explain various Computer Generations in detail.

The Computer Generation means step-by-step growth in the technology. Originally, the term generation was used to distinguish between varying hardware technologies. But nowadays, it has been extended to include both the hardware and the software, which together make up an entire computer system.
                                  There are totally five generations of computer till today. Each generation will be discussed in detail. The following table illustrates the generations of computer hardware :
S. No. 
Generations of computers 
Components used 
Operating speed 

1.
First Generation 
Vacuum tubes
Milli Seconds 

2.
Second Generation 
Transisters
Micro Seconds 

3.
Third Generation 
Integrated Circuits (IC) (or) SSI (or) MSI
Nano Seconds 

4.
Fourth Generation 
Micro processors (or) LSI (or) VLSI
1 to 10 
Nano Seconds 

5.
Fifth Generation 
Ultra LSI
1 to  100 
Nano Seconds 


a) 1st Generation Computers (1942-1955) :-
                                                                           The magnetic relays of the very first computer were replaced by vacuum tubes. The computers which were made of these vacuum tubes came to be known as the first generation computers. The ENIAC computer made use of 18,000 vacuum tubes and relays. It was capable of performing 5,000 additions in one second. It was bulky in size and needed heavy air conditioning.
Advantages :

1. Vacuum tubes were the only electronic components available at that time.
2. This technology made possible the advent of electronic digital computers.
3. These computers were the fastest calculating device of their time.
4. These computers could perform computations in milli seconds.

Disadvantages :

1. Very big in size
2. Occupies large space
3. High heat production
4. High power consumption
5. High cost
6. NO reliability
7. Vulnerable to frequent hardware failure.
8. Limited Commercial use.
9. Need Constant maintenance.

b) 2nd Generation Computers (1955-1964) :
                                                                            The transistor was invented in 1948 at the Bell laboratories and was capable of performing all the functions of a vacuum tube at a much faster rate. It consumed little power and generated less heat. The computers which were working with transistor came to be known as the second generation computers. These computers were much smaller, consumed less power and generated little heat and were more reliable. These had capability of performing 20,000 to 50,000 additions per second.
Advantages :

1. Small in size
2. Better reliability
3. Computational time is micro seconds
4. Less heat generated
5. Better speed
6. Better portability
7. Less prone to hardware failure.

Disadvantages :

1. Frequent maintenance required
2. Need Air-conditioning
3. Manual Assembly of individual components into a functioning unit was required.
4. High cost
5. Commercial production was difficult.

c) 3rd Generation computers (1964-1975):
                                                                          The new techniques of small scale Integration (SSI) and medium scale Integration (MSI) led to the evolution of Integrated Circuit (IC). As many as few hundred transistor can be housed on a single Integrated Circuit. This chip can be as small as 4 to 8 square centimeters in the area and weight few grams. It consumes very little power and its cost is very low. The computers using the integrated circuit came to be known as third  generation computers. The first computer came from IBM and is called as IBM 360. These computers were small in size and Greater in capacity and performed as many as ten million additions per second.
Advantages :

1. Small in size
2. More reliability
3. Less heat generated
4. Computational time is Nano seconds.
5. Less hardware failure.
6. Low maintenance cost
7. Easily portable
8. General purpose computers.
9. Less power required
10. Commercial production was easier and cheaper.

Disadvantages :

1. Need Air-conditioning
2. Highly sophisticated technology required for the manufacture of IC chips.

d) 4th Generation Computers (1975-1989):
                                                                           The beginning of 1970s saw a totally new face in the computer industry with the introduction of microprocessor. These microprocessor comprised of many LSI (Large scale Integration) and VLSI (Very large scale Integration) circuits having all elements to process the data. These microprocessors have thousands of transistors in them. The computers making use of these microprocessors are known as fourth generation computers.
Advantages :

1. These computers were much more small in size.
2. Very cheap as compared with previous generation computers.
3. Consumed less power
4. Mainframe and super computers fall in this generation.
5. Having more reliability
6. Having less hardware failures.
7. They had large and faster primary and secondary storage.
8. These are the general purpose computers.
9. Object oriented languages are supported.

Disadvantages :
     1. Highly sophisticated technology required for the manufacture of LSI chips.
5th Generation Computers (1989-present) :
                                                                           The fifth generation computers have a new technology called Artificial Intelligence incorporated in them. The computers which were made of these Ultra large scale Integration (USING) came to be known as the fifth generation computers. These computers require new architecture, new memory organizations and new programming languages. These will be the computers that can learn and make decisions.
Advantages :

1. The super computers fall under this generation.
2. Portable PC's also fall under this generation.
3. These computers consumes less power than the predecessors.
4. More user friendly
5. Supports wide operating system environments.
6. Supports newer and powerful applications
7. Having much faster and large primary storage capacity
8. The price range are affordable and very close to human being.
9. Supports parallel programming.