Personal computers were first available for home purchase in the 1970s, but the personal computer would not become popular among the masses until 1977. Three competitors released three products that had mass appeal: Apple, Inc.'s Apple II, Commodore Business Machines' Personal Electronic Transactor and Tandy Radio Shack's TRS-80.
Although each of the machines had a limited amount of memory available and ran on 8-bit microprocessors, the computers were affordable for the average person. Before this period, computers were built for businesses and government organizations. They were built much larger and were much more expensive, so they were not practical for home use.
In the mid-1980s, IBM entered the market and brought new competition to the arena. Apple quickly created a new personal computer called Lisa, which had a graphical user interface and allowed the user to perform simple options by using a mouse. IBM countered with its own new products. The rivalries grew throughout the 1980s, and this is when the rivalry between the Macintosh and Windows operating systems began. This rivalry is one of the reasons why personal computers were able to change so quickly with new technological advances. The companies pushed one another to find new technologically savvy ways of using personal computers, as companies also pushed to make the technology user-friendly.