History of the Personal Computer

The personal computer (PC) was not the first computer invented. For many years, large mainframe computers were the only ones available. The development of the first PC was made possible by a previous breakthrough: the invention of the microprocessor chip by Intel in 1971. Following this advance, other breakthroughs formed a trail leading to the first PC: XeroxPARC developed the Xerox Alto in 1973, the first computer that used a graphical display, mouse, menus, and icons. Also in 1971, Alan Shugart at IBM invented the floppy disk. In 1974, Gay Kildall developed the Control Program for Microcomputers (CP/M), the industry-standard operating system until IBM commissioned MS-DOS in 1981 ("A Condensed History of Personal Computing").

In 1974, the Scientific, Electronic and Biological (Scelbi) computer came out, based on Intel's 8008 microprocessor and priced at $565. It had 1K of programmable memory, but users could buy an additional 15K of memory for $2,760. At about the same time, the Mark-8 computer kit designed by Jonathan Titus came out, also based on the 8008 (Bellis).

In 1975, a hobbyist's kit called the MITS Altair 8800 came out, allowing consumers to build their own crude computer using the Intel 8080 CPU; this model had 256 bytes of RAM ("A Condensed History of Personal Computing"). This sparked a response from Bill Gates and a programmer, Paul Allen, who compiled a version of BASIC to run on the Altair. This version of BASIC