MOS Technology 6502

The MOS Technology 6502 (typically "sixty-five-oh-two" or "six-five-oh-two") is an 8-bit microprocessor that was designed by a small team led by Chuck Peddle for MOS Technology. When it was introduced in 1975, the 6502 was, by a considerable margin, the least expensive full-featured microprocessor on the market. It initially sold for less than one-sixth the cost of competing designs from larger companies, such as Motorola and Intel, and caused rapid decreases in pricing across the entire processor market. Along with the Zilog Z80 it sparked a series of projects that resulted in the home computer revolution of the early 1980s.

Popular home video game consoles and computers, such as Atari, Apple II, Nintendo Entertainment System, Commodore 64 and others, used the 6502 or variations of the basic design. Soon after the 6502's introduction, MOS Technology was purchased outright by Commodore International, who continued to sell the microprocessor and licenses to other manufacturers. In the early days of the 6502, it was second-sourced by Rockwell and Synertek, and later licensed to other companies. In its CMOS form, which is produced by the Western Design Center, the 6502 continues to be widely used in embedded applications, with estimated production volumes in the hundreds of millions.