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Chip Hall of Fame: MOS Technology 6502 Microprocessor

From the heroic age of 8-bit CPUs, this processor powered the Apple II, Commodore 64, BBC Micro, and more

2 min read
MOS Technology 6502 Microprocessor
Image: Computer History Museum

Zilog Z80 Microprocessor Image: Computer History Museum

6502 Micro-processor

Manufacturer: MOS Technology

Category: Processors

Year: 1975

When one particular chubby-faced geek stuck one particular chip into one particular computer circuit board and booted it up, the universe skipped a beat. The geek was Steve Wozniak, the computer was the Apple I, and the chip was the 6502, an 8-bit microprocessor developed by MOS Technology. The chip, and its variants went on to become the main brains of ridiculously seminal computers like the Apple II, the Commodore PET, the Commodore 64, and the BBC Micro, not to mention game systems like the Nintendo Entertainment System and the Atari 2600 (also known as the Atari VCS). Chuck Peddle, one of the chip’s creators, recalls when they introduced the 6502 at a trade show in 1975. “We had two glass jars filled with chips,” he says, “and I had my wife sit there selling them.” (In 2016, Peddle admitted that at the time he had only enough working processors for the upper layers of the jars—they were mostly filled with nonworking chips.) Hordes showed up. The reason: The 6502 wasn’t just faster than its competitors—it was also way cheaper, selling for US $25 while Intel’s 8080 and Motorola’s 6800 were both fetching nearly $200.

The breakthrough that permitted this cost reduction, says Bill Mensch, who created the 6502 with Peddle, was a minimal instruction set combined with a fabrication process that “yielded 10 times as many good chips as the competition.” The 6502 almost single-handedly forced the price of processors to drop, helping launch the personal computer revolution. A revised version of the chip is still in production and some manufacturers still use it—in commercial embedded systems—as well as many hobbyists. More interesting perhaps, the 6502 is the electronic brain of Bender, the depraved robot in “Futurama,” as revealed in a 1999 episode.

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The 8-bit 6502 was a smash hit from the get-go when it was released in 1975, due to its low price.

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The HX-63 cipher machine

The HX-63 cipher machine is an electromechanical, rotor-based system designed and built by Crypto AG.
The machine uses nine rotors [center right] to encrypt messages. A dual paper-tape printer is at the upper left.

PETER ADAMS

Growing up in New York City, I always wanted to be a spy. But when I graduated from college in January 1968, the Cold War and Vietnam War were raging, and spying seemed like a risky career choice. So I became an electrical engineer, working on real-time spectrum analyzers for a U.S. defense contractor.

In 1976, during a visit to the Polish Army Museum in Warsaw, I saw an Enigma, the famous German World War II cipher machine. I was fascinated. Some years later, I had the good fortune of visiting the huge headquarters of the cipher machine company Crypto AG (CAG), in Steinhausen, Switzerland, and befriending a high-level cryptographer there. My friend gave me an internal history of the company written by its founder, Boris Hagelin. It mentioned a 1963 cipher machine, the HX-63.

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