A nineteenth century professor Charles Babbage at Cambridge University is considered the father of modern digital computers. During his period, prepared the mathematical and statistical tables was very difficult to make error free. To overcome this error Babbage designed a "Difference Engine" in the year 1822, which could produce reliable mathematical and statistical tables. In 1842, Babbage came out with his new idea of "Analytical Engine", which was intended to be completely automatic. However, his efforts established a number of principles, which have been shown to be fundamental to the design of any digital computer. The evolution of computers are as follows:
First Generation (1942-1955)
First electronic computers used vacuum tubes, and they were huge and complex. The first general purpose electronic computer was the ENIAC (Electronic Numerical Integrator And Computer). It was digital, although it didn’t operate with binary code, and was reprogrammable to solve a complete range of computing problems. It was programmed using plug boards and switches, supporting input from an IBM card reader, and output to an IBM card punch. It took up 167 square meters, weighed 27 tons, and consuming 150 kilowatts of power. It used thousands of vacuum tubes, crystal diodes, relays, resistors, and capacitors.
The first non-general purpose computer was ABC (Atanasoff–Berry Computer), and other similar computers of this era included german Z3, ten British Colossus computers, LEO, Harvard Mark I, and UNIVAC.
Second Generation (1955-1964)
A new electronic switching device, called transistor was invented at Bell Laboratories in 1947. The second generation of computers came about thanks to the invention of the transistor, which then started replacingvacuum tubes in computer design. Transistor computers consumed far less power, produced far less heat, and were much smaller compared to the first generation.
The first transistor computer was created at the University of Manchester in 1953. The most popular of transistor computers was IBM 1401. IBM also created the first disk drive in 1956, the IBM 350 RAMAC.
The first generation computers were mainly used for scientific computations. However, in the second generation an increasing use of computer was seen in business and industry for commercial data processing applications like payroll, inventory control, marketing and production planning.
Third Generation (1964-1975)
The invention of the Integrated Circuits (ICs), also known as microchips, paved the way for computers as we know them today. This IC technology was also known as "microelectronics" technology because it made it possible it integrate larger number of circuit components into very small surface of silicon, known as"chip". This technology was named Small Scale Integration(SSL). With the advancement in technology for manufacturing ICs, it became possible to integrate up to hundred components on a single chip.This technology name to known as Medium Scale Integration(MSI).
Third generation computers were more powerful. more reliable, less expensive, smaller, and cooler to operate than the second generation computers.
Fourth Generation (1975-1989)
After the invention of IC, large number of electronic components packed on a silicon chip. This progress soon led to the era of Large Scale Integration(LSI) when it was possible to integrate over 30,000 electronic components on a single chip followed by Very Large Scale Integration (VLSI) when it was possible to integrate about one million electronic components on a single chip. This progress led to a dramatic development - the creation of a microprocessor.
A microprocessor contains all the circuits needed to perform arithmetic logic and control functions, the core activities of all computers, on a single chip. It started a new social revolution - the personal computer (PC) revolution.
Fifth Generation (1989- Present)
The dramatic increase in the power of microprocessor chips, and the capacity of main memory and hard diskcontinued in the fifth generation. The VLSI technology became ULSI(Ultra Large Scale Integration)technology in the fifth generation, resulting in the production of microprocessor chips, having 10 millionelectronic components.
The tremendous processing power and the massive storage capacity of the fifth generation computers also made them a very useful and popular tool for a wide range of multimedia applications, which deal with information containing text, graphics, animation, audio and video data.
Computer memory is any physical device capable of storing information temporarily or permanently. There are two types of computer memory Primary Memory or Main Memory whicn include RAM (Random Access Memory) & ROM (Read Only Memory) and Secondary Memory or Auxiliary Memory which include Magnetic Disk, Magnetic Tape, Optical Disk etc.
Random Access Memory (RAM) - is a type of volatile memory that is stores information on an integrated circuit which hold the data mainly when the program is beaing executed by the CPU. As it is volatile in nature so it cann't store data permanently.
Read Only Memory (ROM) - a non-volatile memory chip in which data are stored permanently, and cannot be altered by the programmer.
A storage, which suppliments the main memory of a computer. Often reffered to to as secondary storage, this section of computer's memory is non-volatile and has low cost per bit stored, but it generally has an operating speed far slower than that of the primary storage.
A small high speed memory, which is used to increase the speed of processing by making current programs and data available to the CPU at a rapid rate.