In 1952, a major computing company took a decision to get out of the business of making mainframe computers. They believed that there was only a market for four mainframes in the whole world. That company was IBM. The following year they reserved their decision. In 1980, IBM decided that there was a market for 250000 PCs, so they set up a special team to develop the first IBM PC. It went on sale in 1981 and set a world-wide standard for IBM-compatibility, which, over the next ten years, was only seriously challenged by one other company, Apple Computers. Since then, over seventy million PCs made by IBM and other manufacturers have been sold. Over this period, PC shave become commodity items. Since IBM made the design non-proprietary, anyone can make them. The first IBM PC was developed using existing available electrical components. The original IBM PC had a minimum of 16K of memory, but this could be upgraded to 512 if necessary, and ran with a processor speed of 4.77MHz. Ten years later, in 1991, IBM were making PCs with 16Mb of memory, expandable to 64Mb, running with a processor speed of 33MHz. The cost of buying the hardware has come down considerably as the machines have become commodity items. IBM was first co-operate with Digital Research but when the collaboration failed, they turned to Bill Gates, then 25 years old, to write their operating system, that was MS-DOS. The widespread availability of computers has in all probability changed the world forever. The microchip technology, which made the PC possible, has put chips not only into computers but also into washing machines and cars. Some books may never be published in paper form but may only be made available as part of public databases. Networks of computers are already being used to make information available on a worldwide scale. There are as many definitions for the term "network" as there are networks. However, most people would agree that networks are collections of two or more connected computers.
