The earliest computers, known as mainframe computers ,which were dependent on vacuum tube technology filled whole rooms. By 1960 transistors and integrated circuits had become reliable and affordable enough for general use in science, military, business and industry. Over time, computer memory size increased in size and power and decreased in cost. By the 1970s, the cost had decreased enough to make minicomputers available for home and personal use.
Unlike third generation minicomputers which were scaled down versions of mainframe computers, the fourth generation’s origins were fundamentally different. The basis of the fourth generation was the invention of the microprocessor by a team at Intel. In 1971 Intel released the 4004, the world’s first commercial microprocessor. Microprocessor-based computers were originally very limited in their computational ability and speed until Intel’s development of the RAM chip. IBM personal computers benefitted from the 8000 series which provided increased speed and power to personal computers. The popular IBM PC was a commercial success and was cloned by other companies to cash in on the popularity of personal computers, including the Apple in all its varieties. Tomorrow, Computer Software Rita Bay