COMPUTER GENERATIONS

·       COMPUTER GENERATIONS                                                                             

“Generation” in computer talk is a step in technology. It provides a framework for the growth of computer industry.

Originally it was used to distinguish between various hardware technologies, but now it has been extended to include both hardware and software.

 Till today, there are five computer generations which are described as follows:                                                                                                     FIRST GENERATION COMPUTERS:

During the period of 1942 to 1955 first generation of computers were developed. The first generation computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. The vacuum tube was developed by Lee DeForest.

 A vacuum tube was a fragile glass device generally used to amplify a signal by controlling the movement of electrons in an evacuated space.  Most of the first generation computers worked on the principle of storing program instructions along with data in memory of computer so that they

could automatically execute a program without human

intervention. Memory of these computers used

 electromagnetic relays, and users fed all data and instructions into the system punched cards, which were used as input. Programmers wrote instructions in machine and assembly languages because of lack of high level  programming languages in those days.

First generation computers 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 malfunction.                            CHARACTERISTICS:

1) First generation computers were based on vacuum tubes.
2) The operating systems of the first generation computers were very slow.
3) They were very large in size.
4) Production of the heat was in large amount in first generation computers.
5) Machine language was used for programming.
6) First generation computers were unreliable.
7) They were difficult to program and use.                                                      

EXAMPLES: 
UNIVAC1, EDVAC, EDSAC and ENIAC, IBM 701 computers are examples of first generation computing devices. 

SECOND GENERATION COMPUTERS:

During the period of 1955 to 1964 second generation of computers were developed. The second generation computers emerged with development of Transistors. The transistor was invented in 1947 by three scientists J. Bardeen, H.W. Brattain and W. Shockley.

 A transistor is a small device made up of 

semiconductor material like germanium 

and silicon. 

Even though the Transistor were developed in 1947 but was not widely used until the end of 50s

The transistor made the second generation

computers faster, smaller, cheaper, more energy-efficient and more reliable than their first-generation computers. Even though the transistor used in the computer generated enormous amount of heat which ultimately would lead to the damage of the computers but was far better than vacuum tubes.
Second generation computers used the low level language i.e. machine level language and assembly language which made the programmers easier to specify the instructions. 

Later on High level language programming were introduced such as COBOL and FORTRAN.

Magnetic core was used as primary storage.
Second generation computer has faster input /output devices which thus brought improvement in the computer.

CHARACTERISTICS:

1)Transistors were used in place of vacuum tubes.
2) Second generation computer were  smaller in comparison with the first generation computers.
3) They were more than ten times faster in comparison with the first generation computers.
4) They generated less heat and were less prone to failure.
5) They took comparatively less computational time.
6) Assembly language was used for programming.

7) Second generation computers has faster input/output devices.

EXAMPLES:

IBM 7030, NCR 304, IBM 650, IBM 1401, ATLAS and Mark III are the examples of second generation computers.

 THIRD GENERATION COMPUTERS:

During the period of 1964 to 1971 Third generation computers were developed. The third generation computers emerged with the development of IC (Integrated Circuits). The invention of the IC was the greatest achievement done in the period of third generation of computers. IC was invented by Robert Noyce and Jack Kilby in 1958-59.

 IC is a single component containing a number of transistors, resistors and capacitors grown on a single chip of silicon eliminating wired interconnection between components. Transistor were based on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.

IC technology was also known as “micro electrons” technology because it made it possible to integrate larger number of circuit components into very small (less than 5mm square) surface of silicon, known as “chip”.                                                                               

Initially the integrated circuits contained only ten to

twenty components. This technology was named

small scale integration (SSI). Later with advancement in technology for manufacturing ICs, 

it became possible to integrate up to about

hundred components on a single chip. The

technology was known as medium scale integration (MSI).

ICs were smaller, less expensive to produce, more rugged and reliable, faster in operation, dissipated less heat, and consumed less power than circuits built by wiring electronic components manually.

Parallel advancements in storage technologies allowed construction of larger magnetic core based random access memory as well as larger capacity magnetic disks and tapes. Hence third generation computers typically had few megabytes (less than 5 megabytes) of main memory and magnetic disks capable of storing few tens of megabytes of data per disk drive.                    

On software front standardization of high level programming languages, timesharing operating systems, unbundling of software from hardware, and creation of an independent software industry happened during third generation. FORTAN and COBOL were the most popular high level programming languages in those days. Some more high level programming languages were introduced during third generation period. Notable among these were PL/1,

PASCAL, and BASIC.

Keyboards and monitors developed during the period of third generation of computers. The third generation computers 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.

CHARACTERISTICS:

1) IC was used instead of transistors in the third generation computers.

2) Third generation computers were smaller in size and cheaper as compare to the second generation computers.

3) They were fast and more reliable.

4) High level language was developed.

5) Magnetic core and solid states as main storage.

6) They were able to reduce computational time and had low maintenance cost.

7) Input/Output devices became more sophisticated.

EXAMPLES:

PDP-8, PDP-11, ICL 2900, IBM 360 and IBM 370 are the examples of third generation computers

                           FORTH GENERATION COMPUTERS:                                                    

 During 1975-1989 the fourth generation computers were built. The fourth generation computers were the extension of third generation technology. The fourth generation computers emerged with development of the VLSI (Very Large Scale Integration).With the help of VLSI technology microprocessor came into existence. The computers were designed by using microprocessor, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The fourth generation computers became more powerful, compact, reliable and affordable. As a result, they give rise to personal computer (PC) revolution.

For the first time in 1981 IBM introduced its computer for the home user and in 1984 Apple introduced the Macintosh Microprocessor.
During fourth generation, semiconductor

memories replaced magnetic core 

 memories resulting in large random

access memories with very fast access

time. Hard disks became cheaper, smaller,

and large in capacity. In addition to

magnetic tapes, floppy disk became popular as

a portable medium for porting programs and data form one computer system to another.
Significant advancements also took place during fourth generation in the area of large scale computer system. In addition to improved processing and storage capabilities of main frame systems, the fourth generation saw the advent of super computers based parallel vector processing and symmetric multi processing technologies. A supercomputer based on parallel vector processing technology contains a small number of custom designed vector processors which are collected to a number of high speed data access shared memory modules through a custom designed, high bandwidth cross bar switch network. On the other hand, a super computer based on symmetric multiprocessing technology uses commodity microprocessors connected to a shared memory through a high speed bus or a cross bar switch network. Primary builders of super computers of former category included Cray Research and ETA systems, which included IBM, Silicon graphics, and Digital Equipments Corporation.
 High speed computer networking also developed during fourth generation. This enabled interconnecting of multiple computers for communication and sharing of data among them. Local Area Networks (LANs) became popular for connecting computers within organizations or within a campus. Similarly, Wide Area Networks (WANs) became popular for connecting computers located at larger distances. This gave rise to network of computers and distributed systems.

In the area of software for large scale computers, key

technologies that became popular included multiprocessing operating systems and concurrent programming languages. With multi processing operating systems, a main frame system could use multiple processor in such a manner that the subordinate processors could manage the user terminals and peripheral devices, allowing the main processor to concentrate on processing the main program, improving the overall performance.                        

During fourth generation, UNIX operating systems also became popular for use on large scale systems. Additionally, due to proliferation of computer networks, several new features where included in existing operating systems to allow multiple computers on the same network to communicate with each other and share resources.                                                                                                                           Some other software technologies that became popular during fourth generation are C programming language, object oriented software design and object programming. C language combines features of high level programming languages with efficiency of an assembly language. The primary objectives of object oriented software design are to make programs generalized and to build software systems by combining reusable pieces of program codes called objects. To facilitate object oriented software design, several object oriented programming languages were introduced. Out of these, C++ emerged as the most popular object oriented language.                

CHARACTERISTICS

1) The fourth generation computers have microprocessor-based systems.

2) They are the cheapest among all the computer generation.

3) The speed, accuracy and reliability of the computers were improved in fourth generation computers.

4) Many high-level languages were developed in the fourth generation such as COBOL, FORTRAN, BASIC, PASCAL and C language.

5) A Further refinement of input/output devices was developed.

6) Networking between the systems was developed.

EXAMPLES:

IBM 4341, DEC 10, STAR 1000, PUP 11 and APPLE II are the examples of fourth generation computers.          

FIFTH GENERATION COMPUTERS:                                                                    

Duration of fifth generation computers is 1982 – Present. The Fifth Generation Computer Systems project (FGCS) was an initiative by Japan's Ministry of International Trade and Industry, begun in 1982, to create a computer using massively parallel computing/processing. It was to be the result of a massive government/industry research project in Japan during the 1980s. It aimed to create an "epoch-making computer" with-supercomputer-like performance and to provide a platform for future developments in artificial intelligence. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.                                               

Artificial intelligence is the branch of computer science concerned with making computers behave like humans. The term was coined in 1956 by John McCarthy at the Massachusetts Institute of Technology. Artificial intelligence includes the following areas of specialization:

Games Playing: programming computers to play against human oponents.

Expert Systems: programming computers to make decisions in real-life situations (for example, some expert systems help doctors diagnose diseases based on symptoms)

Natural Language: programming computers to understand natural human languages

Neural Networks: Systems that simulate intelligence by attempting to reproduce the types of physical connections that occur in animal brains

Robotics: programming computers to see and hear and react to other sensor stimuli.
The trend of further miniaturization of electronic components, dramatic increase in power of microprocessor chips, and increase in capacity of main memory and hard disk continued during fifth generation.

 VLSI technology became ULSI (Ultra Large Scale Integrated) technology in fifth generation resulting in production of microprocessor chip having ten million electronic components. Infact, the speed of microprocessors and the size of main memory and hard disk doubled almost every eighteen months. As a result, many features found in the CPUs of large main frame systems of third and fourth generation systems became part of micro processor architecture in fifth generation. This ultimately resulted in availability of very powerful and compact computers becoming available at cheaper rates and death of traditional large main frame systems. Recently, processor manufactures started building multi core processor chips instead of increasingly powerful single core processor chip. The multi core chips improved overall performance by handling more work in parallel.

Due to this fast pace of advancement in computer technology, we see more compact and more powerful computers being introduced almost every year at more or less the same price or even cheaper. Notable among these are portable notebook computers that give the power of a PC to their users even while travelling, powerful desktop PCs and work stations, powerful servers, powerful super computers, and handheld computers.

    Storage technology also advanced making larger main memory and disk storage available in newly introduced systems. Currently, PCs having few Gigabytes of main memory and 80-320 gigabytes of hard disk capacity are common. Similarly workstations having 4-64 Gigabytes of main memory and few hundreds of Gigabytes of hard disk capacity are common. RAID (Redundant Array of inexpensive disks) technology enables configuration of a bunch of disks as a single large disk. It, thus, supports larger hard disk space with better in-built reliability. During fifth generation, optical disks (popularly known as Compact Disks or CDs) emerged as a popular portable mass storage media.

 In the area of large scale systems, fifth generation saw the emergence of more powerful super computers based on parallel processing technology. They used multiple processors and were of two types shared memory and distributed memory parallel computers.

 In a shared memory parallel computer, a high speed bus or communication network interconnects a number of processors to a common main memory whereas in a distributed memory parallel computer, a communication network interconnects a number of processors, each with its own memory. These systems use parallel programming technique to break a problem into smaller problem and execute them in parallel on multiple processors of the system. Processors of a shared memory parallel computer use memory access mechanism for communication, where those of a distributed memory parallel computer message passing mechanism for communication. Distributed memory parallel computers have better scalability (can grow larger in capability) then shared memory parallel computers and are now built by clustering together power full commodity workstations by using a high speed commodity switch network. This is known as clustering technology.

During fifth generation, the internet emerged with associated technologies and applications. It made possible for computer users sitting across the globe to communicate with each other within minutes by use of electronic mail (known as email) facility. A vast ocean of information became readily available to computer user through the World Wide Web (known as WWW). Moreover, several new types of existing applications like electronic commerce, virtual libraries, virtual classrooms, distance education, etc emerged during the period.

The tremendous processing power and the massive storage capacity of fifth generation computers also made them a very useful and popular tool for a wide range of multimedia applications dealing with information containing text, graphics, animation, audio and video data. In general, data size for multimedia information is much larger than plain text information because representation of graphics, animation, audio, or video media in digital form requires much larger number of bits than that required for representation of plain text.

In the area of operating systems, some new concepts that gained popularity during fifth generation include Microkernels, Multithreading, and Multicore operating system.

Microkernel technology enabled designers to model and design operating system in a modular fashion. This makes operating systems easier to design and implement, easier to modify or add new services, and allow users to implement and use their own service.

  Multithreading technology is a popular way to improve application for performance through parallelism.

A multicore operation system can run multiple programs at the same time on a multicore chip with each core handling a separate program.

 In the area of programming languages, concepts that gained popularity during fifth generation are JAVA programming language, and parallel programming libraries like MPI (Message Passing Interface) and PVM (Parallel Virtual Machine).

  JAVA is used primarily of the World Wide Web. 
 MPI is used for distributed memory parallel computers and PVM is used for shared memory parallel computers.

CHARACTERISTICS: 

 1) Portable PCs called notebook computers are much smaller, more powerful and handy than PCs of fourth generation allowing users to use computer facility even while travelling.

2) They consume less power than their predecessors do.

3) No air conditioning is required for notebook computers, desktop PCs, and workstations.

4) They are more reliable and less prone to hardware failures, requiring negligible maintenance cost.

5) They have faster and larger primary and secondary storage.

6) They are general purpose machines.

7) Fifth generation computers work with natural language.

EXAMPLES: 
 IBM Notebooks, Pentium PCs, SUN Workstations, IBM SP/2, SGI Origin 2000, PARAM Supercomputers are the examples of fifth generation computers.

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