MOS 6502

MOS Technology · 1975 · MOS Technology 6502

The most important microprocessor in gaming history. The 6502's $25 retail price in 1975 made personal computing economically accessible and powered nearly every significant gaming platform of the late 1970s and early 1980s.

The MOS 6502 was designed by Chuck Peddle and a small team who had left Motorola, producing a processor with a simplified architecture that allowed manufacturing at a fraction of the cost of contemporary chips from Intel and Motorola. At its 1975 launch price of $25 (compared to $179 for the Motorola 6800 it was designed to compete with), the 6502 made microprocessor-based computing economically viable for consumer products rather than just industrial and commercial applications. Steve Wozniak chose the 6502 for the Apple II specifically because of its price; Atari used the 6507 variant (a cost-reduced version with fewer address pins) in the 2600; Commodore used it in the VIC-20 and C64; the BBC Micro's 6502 made it the computer of choice for British schools. The 6502's architecture was clean and efficient for the era: 56 instructions, three general-purpose registers, zero-page memory addressing that provided fast access to 256 bytes of memory treated as additional registers, and a stack-based subroutine mechanism. Game programmers of the 1980s developed encyclopaedic knowledge of its quirks — the RTS bug, page-crossing cycle penalties, the addressing modes that provided speed advantages — and produced code of extraordinary efficiency within the chip's constraints. The 6502's influence on computing was structural: it made the personal computer industry possible by making microprocessors affordable, and the platforms it powered defined gaming for a decade.