First Generation of Computers (1945 – 1956): with Vacuum Tubes
The first generation of computers used vacuum tubes for circuitry and magnetic drums for memory. They were huge, slow, expensive, and often undependable. They also use a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.
First generation of computers relied on machine language, the lowest-level programming language. This is the language understood by computers, to perform operations. They could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.
The ENIAC, EDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal Automatic Computer) are examples of first-generation computers. The UNIVAC was the first commercial computer delivered to the U.S. Census Bureau in 1951.
Second Generation of Computers (1956 – 1963): with Transistors
In 1947 three scientists, John Bardeen, William Shockley, and Walter Brattain working at AT&T’s Bell Labs invented the transistor.
Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 1950s.
The transistor computer did not last as long as the vacuum tube computer lasted, but it was no less important in the advancement of computer technology. There were obvious differences between the transistor and the vacuum tube.
Differences between vacuum tube and transistor
- The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube. One transistor replaced the equivalent of 40 vacuum tubes.
- Transistors were found to conduct electricity faster and better than vacuum tubes.
- Transistors were also much smaller and gave off virtually no heat compared to vacuum tubes.
- The use of transistors marked a new beginning for the computer. Without this invention, space travel in the 1960’s would not have been possible.
Second-generation computers moved from cryptic binary machine language to symbolic, or assembly languages, which allowed programmers to specify instructions in words.
High-level programming languages were also being developed at that time; such as early versions of COBOL and FORTRAN.
These were also the first computers that stored their instructions in their memory, therefore moving from a magnetic drum to magnetic core technology. The first computers of this generation were developed for the atomic energy industry.
Generation of Computers
Third Generation of Computers (1964 – 1971): with Integrated
The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors. This drastically increased the speed and efficiency of computers.
The integrated circuit, or semiconductor chip, packs a huge number of transistors onto a single wafer of silicon.
Robert Noyce of Fairchild Corporation and Jack Kilby of Texas Instruments independently discovered the attributes of integrated circuits.
Placing such large numbers of transistors on a single chip vastly increased the power of a single computer and lowered its cost considerably.
Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors. The hardware was 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.
These third-generation computers could carry out instructions in billions of a second. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.
Since the invention of integrated circuits, the number of transistors that can be placed on a single chip has doubled every two years, shrinking both the size and cost of computers even further and further enhancing its power.
Most electronic devices today use some form of integrated circuits placed on printed circuit boards.
Fourth Generation of Computers (1971 – Present): Microprocessor
The microprocessor brought the fourth generation of computers. Thousands of integrated circuits were built onto a single silicon chip. The first generation filled an entire room, but now a computer can fit in the palm of the hand.
The Intel 4004 chip was developed in 1971. It located all the components of the computer – the central processing unit, memory and input/output controls – on a single chip.
Characteristics of 4th Generation of Computers
This generation is characterized by the following:
- Use of monolithic integrated circuits: millions of transistors put onto one integrated circuit chip
- The invention of the microprocessor: a single chip that could do all the processing of the full-scale computer.
- Faster Speeds: By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers.
- Better efficiency: Because electricity travels about a foot in a billionth of a second, the smaller the distance the greater the speed of computers.
- Less electricity consumption
- Less heat generation.
- Chips were included in other products: Microprocessors moved out of the realm of desktop computers. It was integrated into many areas of life as more and more everyday products began to use microprocessors.
- The invention of microprocessor ushered in the internet: As these small computers became more powerful, they could be linked together to form networks. It eventually led to the development of the Internet.
- Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.
Invention of microprocessor triggered the tremendous growth of computers and its significant impact on our lives.
Ted Hoff, employed by Intel invented the microprocessor. The chip is the size of a pencil eraser and could do all the computing and logic work of the computer. The microprocessor was made to be used in calculators, not computers. It led, however, to the invention of personal computers, or microcomputers.
In the 1970’s people began buying a computer for personal use. One of the earliest personal computers was the Altair 8800 computer kit.
In 1975 you could purchase this kit and put it together to make your own personal computer.
In 1977 the Apple II was sold to the public and in 1981 IBM entered the PC (personal computer) market. In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh.
Fifth Generation (Present and Beyond): Artificial Intelligence and Machine Learning
The aim of the fifth-generation computing is to develop devices that respond to natural language input. These devices are also capable of learning and self-organization. The shift to artificial intelligence is to develop a computer that can perform the basic tasks of man, e.g. thinking.
Fifth generation computing devices, based on artificial intelligence, are still in development. Although some applications, such as voice recognition are being used today. It is believed that the use of parallel processing and superconductors will help to make artificial intelligence a reality.
Quantum computation and molecular and nanotechnology is radically changing the face of computers now and in years to come. The key features of the fifth-generation computers are parallel processing, support for voice recognition, and understanding of natural language. The computers should also be extra fast, reliable, portable, and so on.
 Roderick Hames. (2011). The Computer Generations 7th Grade. Spring Issue: Alton C. Crews Middle School.