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This microprocessor chip shaped computer history right from the Philly ‘burbs

The region's Compuseum crew honor MOS Technology and its 6502 chip, which they say revolutionized personal computing.

Bill Mensch, co-designer of the 6502 chip, explains the importance of the microprocessor chip in personal computing. (Screenshot by Sarah Huffman)
For Jim Scherrer, founder and president of the Compuseum, the 6502 microprocessor chip made Montgomery County’s MOS Technology the “vanguard of personal computing.”

The 6502 chip was created by MOS Technology and introduced to the world in 1975. Steve Jobs and Steve Wozniak, founders of Apple, used the 6502 to build the first Apple computer. The Commodore computer and the first Atari computers were also built using that chip.

“So we owe all we have in personal computing in some indirect way to MOS Technology of Valley Forge, Pennsylvania,” Scherrer told

To honor its importance, the enthusiasts behind the Compuseum, a local nonprofit project focused on honoring and educating about past and current technology, chose to theme their World Computer Day talk this past February around the 6502 chip. They recreated the presentation for Philly Tech Week presented by Comcast 2022 this May.

University City Science Center’s Venture Cafe hosted the virtual event. Among the speakers was electrical engineer Bill Mensch, co-design engineer for the 6502, who talked about the chip’s creation at MOS Technology and the impacts of the chip’s design.

Making history

Mensch worked at MOS Technology from August 1974 to March 1977. During this time, he and his team designed and rolled out the 6502 microprocessor chip.

“The 6502 revolutionized the microprocessor and you could say the computer industry, or the information technology industry, and how it did that is we designed a microprocessor that was 10 times lower costs,” Mensch told The chip was also at least four times faster than competitors and easier to use than other chips because of the accompanying instruction set, he noted.

Mensch said Apple used the 6502 chip to help create their vision of personal computers in your home — and Microsoft built on that revolution. Thus, both companies were directly and indirectly influenced by the creation of the 6502 chip.

Honoring the 6502

According to Scherrer, people across 16 time zones attended the Philly Tech Week talk, including about 100 attendees overall from Germany, the UK, Italy, Australia, and 12 states in the United States. In addition to Mensch, the speaker lineup featured technology professionals who have different experiences in seeing the impact of the 6502 chip, including Dr. Thomas Haigh, Liza Loop, Laurie Wallmark, Daniel Kottke, Bil Herd and Cedric Gaudin-Rockwell.

“That iconic chip, the 6502, means a lot of different things to different people,” Scherrer said. “So we just tried to get them all together.”

The other speakers touched on subjects such as using the 6502 chip to create the Apple 1 computer and the role women played in the history of the 6502 chip.

Compuseum’s ongoing work

According to Scherrer, the Compuseum works to honor Philadelphia’s rich technology history as the location of the first computer (ENIAC), the first computer company (Eckert-Mauchly Computer Corporation) and the first microprocessor for personal computers.

“There’s lots under the covers in Philadelphia, about technology, and information technology and computing that isn’t known and appreciated,” Scherrer said. “It is under-marketed, and our mission at Compuseum was to change that.”

His team decided to create World Computer Day last year to celebrate the 75th anniversary of the ENIAC computer, a part of which is housed at the University of Pennsylvania. For their second year of World Computer Day, they wanted to recognize the impact of the 6502 chip.

“It was a very exciting time for PC-sized computers that could use these microprocessors and controllers that were all smushed down into little things and then were cheap,” Scherrer said. “So it was really the vanguard of personal computing.”

Sarah Huffman is a 2022-2023 corps member for Report for America, an initiative of The Groundtruth Project that pairs young journalists with local newsrooms. This position is supported by the Lenfest Institute for Journalism.

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