Evolution of computers

The term 'computer generation' is often used in relation to the hardware of computers. Each phase of computer development is known as a separate generation of computers. Each phase of development is characterised by type of switching circuits it utilises.

Most computers today use the idea of 'stored program computer' that was proposed by Dr. John Von Neumann in 1945. The Von Neumann architecture is based on three key concepts that are :

1. Data and instructions (program) are stored in a single read-write memory.
2. The memory contents are addressable by locations.
3. Execution takes place in a sequential fashion i.e. from one instruction to the next unless modified explicitly.

The First Generation Computers (1949-55)

The first generation computers used thermionic valves(vacuum tubes) and machine language was used for giving instructions. The computers of this generation were very large in size and had high electricity consumption. Electric failures occurred regularly and hence, computers were not very reliable. Large air conditioners were necessary because the computers generates heat.

Some computers of this generation are :

• ENIAC
• EDVAC
• EDSAC
• UNIVAC-I

Vacuum Tubes

Vacuum tubes lined up in a rack

The Second Generation Computers (1956-65)

A big revolution in electronics took place with the invention of transistors by Bardeen, Brattain and Shockley. Transistors were highly reliable compared to tubes. They occupied only 1/10th time and power needed by tubes.Another major event was the invention of magnetic cores for storage. They were used to construct large RAMs. Machine language as well as assembly language was used for giving instructions. The computers of this generation were very smaller in size as compared to 1st generation and had lower electricity consumption. First operating systems and the core memory were also developed.

Different types of transistors

Some computers of this generation are :

• IBM 1401
• IBM 1620
• IBM 7094
• CDC 1604
• CDC 3600
• RCA 501
• UNIVAC 1108

The Third Generation Computers (1966-75)

ICs

The third generation computers replaced transistors with ICs. The IC was invented by Jack Kilby. Computers got smaller, faster and more reliable. These computers consumed less power. High-level languages also came into existence.

Some computers of this generation are :

• IBM-360 series
• IBM-370/168
• ICL-1900 series
• ICL-2900
• ICL-2903
• CDC-1700
• PDP-11/45
• Honeywell Model 316
• Honeywell-6000 series

The Fourth Generation Computers (1976-Present)

The advent of microprocessors marked the beginning of the fourth generation of computers. Basically, ICs got more smaller and faster. Micro computer series such as IBM and Apple developed. Portable computers or laptops became popular. Data communication and different types of secondary memory with high storage capacity also developed. The computers are being applied in various areas like simulation, visualisation, parallel computing, virtual reality, multi-media etc.

The Fifth Generation Computers (Near Future)

Key features of this generation computers include :

• Parallel Processing
• Superconductors

This generation computing devices, based on artificial intelligence, are still in development, though some applications, such as voice recognition are being used today. Quantum computation and molecular and nanotechnology will change the face of computers in years to come. The goal of Artificial Intelligence(AI) computing is to develop devices that respond to natural language input and are capable of learning and self-organisation.

The computer will, basically, simulate the human brain to reason. Computers will have to be able to classify information, search large databases rapidly, plan, apply the rules which humans regard as clear thinking, make decisions and learn from their mistakes. Input devices to these computers could include speech and visual recognition.

Written by:

Aditi Pansari

1st year CSE