<P> A seminal step in personal computing was the 1973 Xerox Alto, developed at Xerox's Palo Alto Research Center (PARC). It had a graphical user interface (GUI) which later served as inspiration for Apple Computer's Macintosh, and Microsoft's Windows operating system . The Alto was a demonstration project, not commercialized, as the parts were too expensive to be affordable . </P> <P> Also in 1973 Hewlett Packard introduced fully BASIC programmable microcomputers that fit entirely on top of a desk, including a keyboard, a small one - line display and printer . The Wang 2200 microcomputer of 1973 had a full - size cathode ray tube (CRT) and cassette tape storage . These were generally expensive specialized computers sold for business or scientific uses . The introduction of the microprocessor, a single chip with all the circuitry that formerly occupied large cabinets, led to the proliferation of personal computers after 1975 . </P> <P> 1974 saw the introduction of what is considered by many to be the first true "personal computer", the Altair 8800 created by Micro Instrumentation and Telemetry Systems (MITS). Based on the 8 - bit Intel 8080 Microprocessor, the Altair is widely recognized as the spark that ignited the microcomputer revolution as the first commercially successful personal computer . The computer bus designed for the Altair was to become a de facto standard in the form of the S - 100 bus, and the first programming language for the machine was Microsoft's founding product, Altair BASIC . </P> <P> In 1976, Steve Jobs and Steve Wozniak sold the Apple I computer circuit board, which was fully prepared and contained about 30 chips . The Apple I computer differed from the other kit - style hobby computers of era . At the request of Paul Terrell, owner of the Byte Shop, Steve Jobs was given his first purchase order, for 50 Apple I computers, only if the computers were assembled and tested and not a kit computer . Terrell wanted to have computers to sell to a wide range of users, not just experienced electronics hobbyists who had the soldering skills to assemble a computer kit . The Apple I as delivered was still technically a kit computer, as it did not have a power supply, case, or keyboard as it was delivered to the Byte Shop . </P>

When was the first pc sold to the public