The word ‘computer’ originally implied a person, who, under instructions from a mathematician, performed mechanical calculations. Mechanical calculating devices such as the abacus were often put to use to aid this process.
At the end of the Middle Ages, mathematics and engineering in Europe received a considerable boost, thus leading to the invention of numerous mechanical calculating devices. The technology for clockwork was developed by the early 17th century. The period between the early 19th century and early 20th century saw the development of a number of technologies which would be vital for the development of the digital computer later on. Some examples are the punched card and the valve. Charles Babbage was the first person to design a fully programmable computer as early as 1837. However, he was unable to actually construct his computer due to a variety of reasons.
Analog computers were increasingly used in the first half of the 20th century for a number of scientific computing needs. However, they became obsolete after the development of the digital computer.
The first digital computer was the Atanasoff Berry Computer . It used a binary system of arithmetic, parallel processing, a separation of memory and computing functions and regenerative memory. Binary math and electronic circuits – both of which are used in today’s computers – were first used in the Atanasoff Berry Computer.
In the 1930’s and 1940’s, newer and more efficient computers were continuously developed. Gradually, they came to possess the key features which are present in modern day computers – digital electronics and flexibility of programming.
Among the more important machines to be developed during this time, the American ENIAC was prominent. It was a general purpose machine, but had an inflexible architecture. Later a far superior technique known as the stored program architecture was developed. It is the foundation from which all modern computers are derived.
Throughout the 1950’s, computer design [http://www.online-computers.info] was primarily valve driven. This was later replaced by transistor-driven design in the 1960’s. Transistor-based computers were smaller, faster and cheaper, and hence commercially viable. Integrated circuit technology, adopted in the 1970’s enabled computer production costs to hit a new low, so that even individuals could afford them. That was the birth of the personal computer, as it is known today.