Generation of computers:

A generation of computer refers to the state of improvement in the development of computer science and its technology. In terms of technology and used system computer has been divided into five generation. It is classified on the basis of size, its power, its reliability, processing speed, used memory, acceptable application and many more.

First generation of computer (1945-1956) :( Vacuum tubes)
The main features of first generation computer are listed below:
• It used vacuum tube as electronic circuit.
• The magnetic drums were used as primary storage and punch cards were used as secondary device.
• They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctioning.
• First generation of computers fully depends upon machine language to perform operations, and they could only solve one problem at a time.
• Operating speed was used in terms of millisecond. Every CPU has its own unique machine language. Programs must be rewritten or recompiled, therefore to run in different types of computer.
• Input was based on punched cards and paper tapes, and output was displayed in printouts.
• Examples: - Mark I , UNIVAC, ENIAC, EDSAC, etc

Second generation computer (1956-1963) :( Transistor)
The main features of second generation computer are listed below:
• Transistors replaced vacuum tubes and emerged in the second generation computer.
• Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instruction in words.
• High-level programming languages were also being developed at this time, such as early version of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from magnetic drums to magnetic core technology.
• Magnet core memory was used as internal storage and magnetic tapes used as secondary storage.
• They have little bit faster I/O devices (input/output).
• Processing speed measured in micro-seconds.
• Example: IBM 1401, 7070, 7030, ICL 2950/10, Honeywell 800, 400 series. Etc.


Third generation computer (1964-1971): (Integrated Circuits IC)
The main features of third generation computer are listed below:

• Semi conductor memory was used as primary storage and magnetic discs were used as secondary storage.
• Massive use of high level language.
• Processing speed increased to nanosecond and even faster.
• Intend of punched cards and printouts, users interacted with third generation computers though keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory.
• Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.
• Examples- IBM 360 series, UNIVAC 9000, GE 235, Honeywell 200, Burroughs 6700 .Etc.


Fourth generation computers (1971-present): (VLSI or microprocessor)
The main features of fourth generation computer are listed below:

• Massive use of magnetic and optical storage devices with capacity more than 100 GB
• Advancement in software and high level language.
• Use of 4th generation language (4GL).
• Operation speed increased beyond picoseconds and MIPS( Millions of Instructions Per Second)
• As this computer became more powerful, they could be linked together to form network, which eventually led to the development of internet. Fourth generation computer also saw the development of GUI’s the mouse and hand held devices.
• Example: - IBM PC, Pentium PC, Apple/Macintosh etc.

Fifth generation computer (Present and beyond): (Biochips)
The main features of fifth generation computer are listed below:
• Fifth generation computing devices based on artificial intelligence, are still in development, though there are some application such as voice recognition, that are widely used today. It is also known as Artificial Intelligence.
• Currently no computers exhibit full artificial intelligence (that is, are able to simulate human behavior or behave like human beings or think as human beings). The greatest advances have occurred in the field of gaming like 3D games. The best example is a chess program that is able to beat humans.
• The fifth generation computers will have this following features like interactive game playing, expert system, understanding natural language, neural networks, robotics, acting like an human, can have own thinking capacity.
This is all about the generation of computer.

Characteristics of computer:

All digital computers, regardless of their size are used to transmit, store and manipulate information (data). Several different types of data can be processed by a computer. These include numeric, data character data, graphic data and sound etc. the most common two types of data is numeric data and character data. Scientific and technical application is mostly concerned with numeric data where as business field requires both numeric as well as character data.
To process a particular set of data, the computer must be given a appropriate set of instruction that is called the program as we discussed it above. These instructions are entered into the computer and it is stored in a portion of computer’s memory.
A stored program can be executed at any time as our want. For example:
1. A set of instruction that is input data will be entered into the computer through input device called keyboard and is stored in a portion of computer’s memory known as hard disk.
2. The input data will be processed to produce certain desired result as an output.
3. And finally the output will be printed in a sheet of paper or displayed through out put device known as monitor.
These three things can be repeated as many times we want and processing of it depends upon how much is to be calculated or processed.

History of computer:

• A brief history of computer is pointed below:
  History of computer was started when the people in the early civilization started keeping records of transaction on clay. This was the starting of history of computer in 1200BC.
  • Actual computing started around 300BC when Babylon invented the ABACUS.
  • In 1642, Blaise pascal invented a gear driven adding machine which we called a calculator now a days but its name was PASCALENE, which was the first mechanical adding machine.
  • In 1673, Leibnitz developed a machine named STEPPED RECKONER that could multiply.
  • In 1801, jacquard constructed a LOOM, which was the first machine programmed with punched cards.
  • In 1822, Charles Babbage designed and build first DIFFERENCE ENGINE which was certificated the first mechanical computer. So he is known as the father of computer science.
  • In 1842, lady Ada Augusta Lovelance wrote the first program for the difference engine made by Babbage.
  • In 1847, Babbage designed his second version of difference engine but it could not be completed and was conceived on 1891 by the science museum in England.
  • In 1854, George Bool developed Boolean logic, which is the system for symbolic and logical reasoning and basis for computer design.
  • In 1890, PUNCHED CARD machine was developed in USA.
  • Before the development of vacuum tubes all the machines were mechanical.
  • The first electronic computer ENIAC (electronic numerical integrators and computer) was built in 1946.
  • After the many machine like EDVAC (Electronic discrete variable automatic computer), IBM 701, 704 were built using transistors instead of vacuum tubes.
  • In 1961, integrated circuit(IC) chips were commercially available.
  • Science then computers uses ic’s instead of transistors.
  • IBM 360 (international business machine) and DEC PDP 8 (programmed data processor, digital equipment corporation) were the most popular machine at that time.
  • Altair 8800 was the first easily available PC(personal computer)
  • In 1891, IBM launched the PC.
  • Science then, there has been significant development in the field of microelectronics and microprocessor.
  • Today there are lots of microprocessor with more then 2GHz (Gigahertz) processor on our desktop and 8 GB (Gigabyte) and more of memory and more than 500GB (Gigabyte) of storage.

What is computer?

A digital computer is such an invention of 20th century that has widely spread in each and every field of human life. A digital computer is an electronic programmable machine that can process almost all kinds of data. The programmable feature has made this machine unique as compared to other machines. The same machine can be used in small shop, in medical science, for space-research and various engineering activities. All this is possible by using different programs for different environment/applications. What is a program? A program is a set of instructions, written in particular sequence in a computer-related language.

Introduction: to Computer

Computer simply is defined as an electronic device which calculates the raw data given by user and gives the valuable result as an output.
Today’s computers come in many different forms. They range from massive, multipurpose mainframes and supercomputers to desktop-size personal computers. Between these extremes is a vast middle ground of minicomputers and workstations. Large minicomputers approach mainframes in computing power, whereas workstations are powerful personal computers.
Mainframes and large minicomputers are used by many businesses, universities, hospitals and government agencies to carry out sophisticated scientific and business calculations. These computers are expensive (large computers can cost millions of dollars) and may require a sizeable staff of supporting personal and a special carefully controlled environment.
Personal computer on the other hand is small and expensive. In fact, portable, laptop computers weighing less then 5-6 pounds are widely used by everyone now days. Personal computers are mostly used by schools and business and it is being used in household items too. Now days computers is thought from the primary level that is from 5 on words some school used it from the class 3 too.
This is the generation of computer, each and every field is using computer, it is said that this 21st century age is known as computer age. If one fails to take the knowledge of computer then it is believed that he/she can’t do anything in his life. The cost of these personal computers is so low that a single family can afford 2 of it; each and every family has got one computer.

Computer-introduction