An international conference in 1962 classified computers into 5 distinct generations – 3 of which are already passed by and we are in fourth generation now. The fifth generation computers are undergoing research and a few computers of this generation are developed that meets some of the expected feature of fifth generation.
Each generation of computers 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.
There are often questions in PSC Exam like what characterizes a computer of particular generation. Following is a question from 2011 exam:
33. How was the generation of computer classified?
a. By the model of the computer
b. By the device used in memory & processor
c. By the time period
d. None of the above
In fact, each computer is classified into different generations based on what electronic component it used. It’s not the time period, nor the model.
I’d included this question in sample test for the participants of eCourse and surprisingly found that many students did the very mistake. Vacuum tubes, transistors, ICs, LSI & VLSI chips are used as switching components or memory and processing devices.
First generation computers used vacuum tubes as switching device and magnetic drum for memory. These computers were often huge, occupying an entire hall.
Because first generation computers used vacuum tubes, they consumed a lot of electricity and produced excessive heat. You require cooling facilities to operate computers. This was the major problem of this generation of computers. Moreover, these tubes burned out because of too much heating and need to be replaced more frequently.
The operation cost of these computers was too expensive.
In first generation computers, the operating instructions or programs were specifically built for the task for which computer was manufactured. The Machine language was the only way to tell these machines to perform the operations. There was great difficulty to program these computers and more when there were some malfunctions.
Since when the first generation computers started?
There are two different views regarding from when the first generation began. Some believe that it started from 1946 when the first computer using valve – ENIAC – was developed. Do you remember how many vacuum tubes ENIAC used?
Some othersargue that we should consider EDSAC as the first computer of first generation because it is the first computer to use stored procedure – a true computer in modern sense. ENIAC was just a calculator! If you consider EDSAC is the first computer of first generation, then 1949 should be the starting of first generation.
Note: There is no fixed and generally agreed date for any of the generations. In fact the computers are classified into different generations based on the switching component and technology rather than time slots. Consider the dates as tentative.
More generally the duration of first generation computers is 1946 to 1954.
Features of First Generation Computers
- They used vacuum tubes or valves as main electronic component
- They were large in size, slow in processing and had small storage capacity
- They consumed lots of electricity and produced excessive heat
- They were less reliable than later generation computers
- They used machine level language for programming
Examples of First Generation Computers
The vacuum tube was an extremely important step in the advancement of computers. Vacuum tubes were invented the same time the light bulb was invented by Thomas Edison and worked very similar to light bulbs. Its purpose was to act like an amplifier and a switch. Without any moving parts, vacuum tubes could take very weak signals and make the signal stronger (amplify it).Vacuum tubes could also stop and start the flow of electricity instantly (switch).These two properties made the ENIAC computer possible.
In 904, John Ambrose Fleming invented the first practical electron tube called the ‘FlemingValve’. Feming invents the vacuum tube diode.
In 1906, Lee de Forest invented the ‘audion’ later called the triode, an improvement on the ‘Fleming Valve’ tube.
In 1906 the American physicist Lee De Forest invented vacuum tube triode. It was the first three terminal device and enabled amplification and switching of electrical signals. Though it helped to push the development of technology a great deal, it had its own problems. The metal that emitted electrons in the vacuum tubes burned out. It occupied lot of space, consumed much power and produced heat.
In 1947 the three Americanphysicists – John Bardeen, William Shockley, and Walter Brattain – at Bell Telephone Laboratories invented transistors. They received the 1956 Nobel Prize jointly for this awesome invention.Transistors proved to be a much better alternative to the vacuum tubes. They were much smaller, produce low heat and were very reliable. This made it possible to develop computers smaller, efficient and more reliable.
Second Generation of Computers (1955 to 1964)
By 1948, the invention of the transistor greatly changed the computer’s development. Coupled with early advances in magnetic-core memory, transistors led to second generation computers that were smaller, faster, more reliable and more energy-efficient than their predecessors.
The first large-scale machines to take advantage of this transistor technology were early supercomputers – Stretch by IBM and LARC by Sperry-Rand. These machines were costly, however, and tended to be too powerful for the business sector’s computing needs, thereby limiting their attractiveness.
A remarkable improvement realized in this generation was the development of assembly language. Assembly language was abbreviated programming codes to replace the machine language – the difficult binary codes.
Towards the early 1960′s, there were a number of commercially successful second generation computers used in businesses, universities, and government. They contained all the components we associate with the modern day computer: printers, tape storage, disk storage, memory, and stored programs.
One important example was the IBM 1401, which was universally accepted throughout industry. This is the first computer to enter into Nepal as well. Nepal brought this computer for the census of 2028 BS.
It was the stored program and programming language that gave computers the flexibility to finally be cost effective and productive for business use.
CLARIFICATION: The stored program concept means the instructions to run a computer for a specific function (known as a program) were held inside the computer’s memory, and could quickly be replaced by a different set of instructions for a different function.
More sophisticated high-level languages such as COBOL (Common Business-Oriented Language) and FORTRAN (Formula Translator) came into common use during this time, and have expanded to the current day.
Features of Second Generation Computers
- Second generation computers used transistors as their main electronic component.
- These computers were much smaller, reliable and more powerful
- Apart from machine language, assembly language were developed and used in this generation
- Some high level languages like COBOL & FORTRAN were introduced towards the end of second generation
- The computers of second generation used ‘Stored Program Concept’
- Printers, tape storage, disk storage, memory were started from second generation of computers
- Processing speed improved to microseconds
Examples of Second Generation Computers
IBM 7030 Stretch
Many people enjoy a misconception that all larger computers are from older generations and small computers are the fourth generation computers. Remember, computers are classified into different generations NOT based on their sizes. Though it is true that the old computers were compelled to be of bigger size (larger components and lack of advanced technology).
The vacuum tubes used in first generation were replaced by transistors in second and which in turn were replaced by ICs (Integrated Circuits) in third generation computers. So, first of all, let’s look at those ICs.
Integrated Circuit (IC) is a small electronic device made out of semiconductor material. The first integrated circuit was developed in the 1950s by Jack Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductor. – WeboPedia
It is amusing to know that two people thought about the same solution but independently. Here is the interesting story about how Robert Noyce got the patent.
Please check R.C. Khanal’s ‘Computer Concept‘ book. He has nicely explained how these IC Chips are manufactured in ‘Computer Generations’ chapter. Notice the terms silicon, wafers, and photolithography.
So, after the invention of IC Chips, it is possible to integrate thousands of registers, diodes, capacitors and many other electronic components and circuitry in a tiny chip.
Integrated circuits are referred with different names like Chips, ICs, Microchips, and so on.
A tiny chip contains the whole electronic network that performs complex tasks.
Types of Integrated Circuits
- SSI (small-scale integration):
Up to 100 electronic components per chip
- MSI (medium-scale integration):
From 100 to 3,000 electronic components per chip
- LSI (large-scale integration):
From 3,000 to 100,000 electronic components per chip
- VLSI (very large-scale integration):
From 100,000 to 1,000,000 electronic components per chip
- ULSI (ultra large-scale integration):
More than 1 million electronic components per chip
Third Generation Computers (1964-1971)
The computers using small scale integration circuits (SSI)and medium scale integration circuits (MSI) are under this class. The invention of IC Chips made it possible to greatly reduce the size of computers with improvement in operation speed (nanoseconds) and reliability.
The most noticeable achievement of third generation is the development of operatingsystems. The operating systems allowed the machines to run many different applications. These applications were monitored and coordinated by the computer’s memory.
In 1969 AT&T Bell Laboratories programmers Kenneth Thompson and Dennis Ritchie developed the UNIXoperating system on a spare DEC minicomputer. UNIX was the first modern operating system that provided a sound intermediary between software and hardware. UNIX provided the user with the means to allocate resources on the fly, rather than requiring the resources be allocated in the design stages. The UNIX operating system quickly secured a wide following, particularly among engineers and scientists at universities and other computer science organizations.
User interface devices such as Keyboards&Monitors started from this generation. Similarly, GUI also was started from third generation. These are important development of third generation.
Characteristics of Third Generation Computers
- Third Generation Computers were based on integrated circuit (IC) technology.
- Third Generation Computers were able to reduce computational time from microseconds to nanoseconds
- Third Generation Computers utilized operating systems to centrally control and made it possible for multiple programs to run on a computer
- Users interacted with computers through keyboards and mouse rather than traditional punched cards and printers.
- Third Generation Computers devices consumed less power and generated less heat. In some cases, air conditioning was still required.
- The size of Third Generation Computers was smaller as compared to previous computers
- Since hardware of the Third Generation Computers rarely failed, the maintenance cost was quite low.
- Extensive use of high-level language became possible in Third Generation Computers.
- Manual assembling of individual components was not required for Third Generation Computers, so it reduced the large requirement of labor & cost. However, for the manufacture of IC chips, highly sophisticated technologies were required
- Commercial production became easier and cheaper.
Fourth Generation Computers
Fourth generation for the computers is the era of blooming in multiple dimensions rather than invention of electronic components. Fourth generation computers use ICs as in third generation. But third generation computers used Small Scale and Medium Scale ICs where as in fourth generation Large Scale ICs (LSI), Very Large Scale ICs (VLSI) and the Ultra Large Scale ICs (ULSI) are used.
As millions of electronic components got integrated in a tiny chip, the computers became very small with increased speed, reliability and reduction in cost.
The size of computer reduced to mini computers and microcomputers. Today, we have laptops, palm tops and pocket PCs.
Probably the most important development in this generation is microprocessor. The Intel4004 chip, developed in 1971, took the integrated circuit one step further by locating all the components of a computer (central processing unit, memory, and input and output controls) on a minute chip. Whereas previously the integrated circuit had had to be manufactured to fit a special purpose, now one microprocessor could be manufactured and then programmed to meet any number of demands. Soon everyday household items such as microwave ovens, television sets, and automobiles with electronic fuel injection incorporated microprocessors
In this generation mini computers were built that had more user friendly software packages like word-processor and spreadsheet calculation.
In 1981, IBM introduced its personal computer (PC) for use in the home, office and schools. Other companies made the clones of IBM PCs to make the personal computers more affordable.
In 1984 Apple developed its Macintosh line. Notable for its user-friendly design, the Macintosh offered an operating system that allowed users to move screen icons instead of typing instructions. Users controlled the screen cursor using a mouse.
Fourth generation is the duration when we saw the tremendous improvement in operating systems and high level programming language.
As the small computers become powerful, it was possible to link and work in cooperative environment. This led to the invention of networking. WAN, MAN, LAN and PAN networks came into existence.
Fifth Generation Computers
Up to the fourth generation we saw how computers evolved as the switching devices improved. Fifth generation computers are future computers.
In 1982 Japan started a project named Fifth Generation Computer Systems Project (FGCS) initiated to create a “fifth generation computer” which was supposed to perform much calculation using massive parallel processing. The project was to create the computer over a ten year period, after which it was considered ended and investment in a new, Sixth Generation project, began. Opinions about its outcome are divided: Either it was a failure, or it was ahead of its time. Anyway, it’s out of our context for the moment. I just wished to make you aware you of this fact.
Fifth generation computers are anticipated new type of computer based on emerging microelectronic technologies with high computing speeds and parallel processing. Other major expectations out of this generation are the ability to use natural language and acquire artificial intelligence (AI). Computers will be able to learn by its experience. These computers are being made using ULSI (Ultra Large Scale IC) and Bio-Chips.
We can see some development in achieving these features already. Parallel processing, voice recognition systems and some level of intelligence is been already realized.
CLARIFICATION: Use natural language – computers will be able to understand and use the language that we use in speaking rather than the specially structured commands we are still using in computers.
Examples of Fifth Generation Computers
If y are looking for the examples of fifth generation computers, PIM/m, PIM/p, PIM/i, PIM/k, PIM/c are the computers.
Points to Remember
- An international conference in1962 divided the development of computers into five distinct generations based on main electronic component used on them.
- The computers that used vacuum tubes are first generation computers and they range the date 1946 to 1958.
- Vacuum tube diode was first developed by the English physicist Sir John Ambrose Fleming.
- Vacuum tube triode was invented in 1906 by the American engineer Lee De Forest.
- First generation computers were very large, consumed a lot of power producing excessive heat. They had low level of accuracy and reliability.
- Machine language was used to program first generation computers.
- Because thousands of vacuum tubes were used, they produced a lot of heat. Cooling facility was required in any room where computers were installed. Vacuum tubes were burnt out frequently and maintenance cost was very high. This was the main drawback of first generation of computers.
- Second generation computers used transistors as their main electronic component. Transistorwas much smaller, produced almost no heat and thus, they had a tremendousimpact in development of computers and other electronic devices.
- Second generation computers were developed in 1959 to 1964
- Transistors were invented in 1947 by trio Bell Lab scientists – Walter Brattain, John Bardeen, and William Bradford Shockley.
- Assembly language was used to program second generation computers.
- Magnetic tapes and disks were used as main secondary storage media.
- Third generation computers were developed in 1965 to 1974 that used integrated circuits (ICs) also called microchip as main electronic component.
- Transistors were invented by two scientists independently in 1958 – Jack Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductor Corporation.
- Monitors and Keyboards were introduced in third generation for input and output of data.
- High level languages were use to program in third generation.
- Fourth generation computers are developed during 1975 to 1990 which used LSI and VLSI microprocessors.
- Invention of microprocessors is the most startling development in fourth generation.
- Personal Computers (PCs) were introduced and are very popular. GUI was developed in fourth generation.
- The first microprocessor called Intel 4004 was developed by American Intel Corporation in 1971.
- The fifth generation computer project conducted jointly by several Japanese computer manufacturers under the sponsorship of the Japanese government, emphasized artificial intelligence.
- Artificial intelligence is the branch of computer science concerned with designing intelligent computer system that possesses reasoning, learning and thinking capabilities resembling those of a human being.
- Fifth generation computers will use super conductor technology – Gallium Arsenide chips or Biochips.
- Quantum computation and nanotechnology will radically change the face of computers in years to come.