Companies & Studios

MOS Technology

The chip fab that changed everything

MOS Technology created the 6502 processor and the engineers who designed the SID and VIC-II—the silicon heart of the Commodore 64.

C64Amiga chip-makershardware-pioneers 1969–1994

Overview

MOS Technology never made computers, but they made computers possible for ordinary people. Their 6502 processor—cheap, capable, and elegantly designed—powered the Apple II, the Commodore 64, the Atari 2600, and the NES. When Commodore acquired them in 1976, they gained not just a chip fab but the engineers who would create the most beloved home computer ever made.

Fast facts

  • Founded: 1969 in Valley Forge, Pennsylvania.
  • The 6502 (1975): designed by Chuck Peddle and team, it sold for $25 when competitors charged $300.
  • Commodore acquisition (1976): Jack Tramiel bought MOS to secure chip supply during the calculator wars.
  • Key engineers: Bob Yannes (SID chip), Al Charpentier (VIC-II).
  • End: operated as Commodore Semiconductor Group until Commodore’s bankruptcy in 1994.

The 6502 revolution

The 6502 processor changed computing:

  • Price disruption: at $25 (later dropping to $8), it enabled affordable computers when the Intel 8080 cost $360.
  • Elegant design: 56 instructions, 13 addressing modes, designed for efficient hand-coded assembly.
  • Universal adoption: Apple II, Commodore PET/VIC-20/C64, Atari 400/800/2600, BBC Micro, NES (via Ricoh 2A03).

The engineers who created it—Chuck Peddle, Bill Mensch, Rod Orgill—had defected from Motorola, bringing expertise and determination to beat their former employer.

Commodore’s secret weapon

When Jack Tramiel acquired MOS in 1976, he gained:

  • Vertical integration: Commodore now controlled chip design and fabrication, slashing costs.
  • Engineering talent: the team that would create the C64’s custom chips.
  • Competitive advantage: competitors buying chips at retail couldn’t match Commodore’s prices.

The C64 chips

MOS engineers created the silicon that made the C64 special:

SID (6581) - designed by Bob Yannes:

  • Three oscillators with four waveforms each
  • ADSR envelopes, ring modulation, filter
  • The most musically capable sound chip of its generation

VIC-II (6567/6569) - designed by Al Charpentier:

  • 320×200 hi-res, 160×200 multicolour
  • Eight hardware sprites with collision detection
  • Raster interrupts enabling demo tricks
  • Smooth scrolling

Together with the 6510 CPU (a 6502 variant with I/O port), these chips gave the C64 capabilities no competitor could match at the price.

Legacy

MOS Technology’s influence extends through nearly every classic gaming platform. The 6502’s instruction set is still learned today by retro enthusiasts. The SID chip launched a music scene that endures. And the philosophy—elegant design, aggressive pricing, vertical integration—shaped how Commodore did business until the end.

See also