The development of computing dates back from the early Sumerian civilization (4000-1200 BC) when people started to keep records of transactions on clay tables. The actual computing using a machine started around 3000 BC when Babylons invented the abacus and Chinese people started using them around 1200 BC.
No significant development took place until seventeenth century. In 1642-43 Blaise Pascal created a gear-driven adding machine named Pascalene. It was the first mechanical adding machine. Later, in 1673-74, Leibnitz joined the crew with his version of mechanical calculator named “Stepped Reckoner” that could multiply. In 1801 Jacquard constructed a Loom, which is the first machine programmed with punched cards. In 1822, Charles Babbage designed and built his first Difference Engine, which is credited the first mechanical computer. For this machine, Babbage is known as the “Father of Computer”. In 1842, Ada Augusta Lovelace wrote the first program for the Difference Engine made by Babbage. A programming language (Ada) has been named after her. In 1847-49, Babbage designed his second version of Difference Engine but he could not complete it. The same machine was conceived in 1991 by the Science Museum in Kensington, England, and it worked!
In 1854 George Bool developed Boolean Logic, which is a system for symbolic and logical reasoning and the basis for computer design. In 1890, computations for the US Census were carried out by Herman Hollerith’s punched card machine. Hollerith started Tabulating Company, which eventually became IBM.
Before the 20th century, all the machines were mechanical. With the advent of vacuum tubes, the electronics era of computers started. In 1944, Harvard Mark I, the first large scale, automatic, general purpose, electromechanical calculator driven by a paper tape containing the instructions was constructed. In the second version of this machine, Grace Hopper, found the first computer bug, a bug beaten to death in the jaws of a relay, which she glued into the logbook. The logbook is now in the National Museum of American History of the Smithsonian.
The first electronic computer, ENIAC (Electronic Numerical Integrator And Computer) was built in 1946. It was programmed through rewiring between the various components. After this, many machines like EDVAC, IBM 701, 704 were built and some of them were commercially successful at that time because they used transistors in place of vacuum tubes thereby increasing the reliability and performance.
In 1961, Integrated Circuit (IC) were commercially available and since then computers use ICs instead of individual transistors or other components. IBM 360 and DEC PDP 8 were the most popular machines during that time. The invention of microprocessor further reduced the size and increased the performance of the computers. Altair 8800 was the first easily available microcomputer for which Bill Gates co-wrote BASIC.
1981 was the year of IBM when it launched the PC. Since then, there had been significant development in the field of microelectronics and microprocessor. Today, we run a 2GHz processor on our desk with 256MB of memory (640KB was considered more than sufficient once upon a time) and more than 40G of storage.
Five Generations of Modern Computers
The development of computers has been divided into generations. Computers of each generation have certain common characteristics in terms of components used, computing power, reliability etc.
First Generation (1945-1956)
The computers of this generation we entirely mechanical or electromechanical that use vacuum tubes and relays. Some of the important machines of this generation were Colossus, Mark I, ENIAC, EDVAC etc. The machines were very slow (3-5 seconds per calculation to few thousands of calculations per second) and inflexible (mostly built for special purpose) and could perform basic operations. The machines were huge (eg. ENIAC -18000 ft3, 18000 vacuum tubes) and consume a lot of power (160 KW for ENIAC).
Second Generation Computers (1957-1963)
By 1948, the invention of the transistor greatly changed the computer's development. The transistor replaced the large, cumbersome vacuum tube in televisions, radios and computers. As a result, the size of electronic machinery has been shrinking ever since. The transistor was at work in the computer by 1956. 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.
Throughout the early 1960's, there were a number of commercially successful second-generation computers used in business, universities, and government. These second generation computers contained transistors in place of vacuum tubes. They also contained all the components we associate with the modern day computer: printers, tape storage, disk storage, memory, operating systems, and stored programs. One important example was the IBM 1401. 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. These languages replaced cryptic binary machine code with words, sentences, and mathematical formulas, making it much easier to program a computer. New types of careers (programmer, analyst, and computer systems expert) and the entire software industry began with second-generation computers.
