The MOS Technology 6502 Microprocessor 1975 - Created by Chuck Peddle with Bill Mensch and the Team
Peddle recognized a market for a very low price microprocessor and began to champion such a design to complement the $300 Motorola 6800. His efforts were frustrated by Motorola management and he was told to drop the project. He then left for MOS Technology, where he headed the design of the 650x family of processors; these were made as a $25 answer to the Motorola 6800. The most famous member of the 650x series was the 6502, developed in 1975, which was priced at 15% of the cost of a $175 Intel 8080, and was subsequently used in many commercial products, including the Apple II, PET, VIC-20, Atari 8-bit computers, arcade video games, Oric computers, and the BBC Micro. The Atari 2600 uses the closely related 6507 CPU, the Commodore 64 uses the also closely related derivative 6510, and the Nintendo Entertainment System uses a custom ASIC which includes an altered 6502 core (with the decimal mode deleted). The Furbies that first sold for christmas 1998 had a MOS 6502 inside.
Along with three other engineers at MOS Technology, Mensch holds the patent on the decimal correct circuitry in the 6502 CPU. He was responsible for the design of basic circuits, oscillator, and buffer, transistor sizing, and instruction decode logic, wishing to minimize the number of levels of logic to achieve faster operation. During this time, when it was common to make errors during design, Chuck Peddle had praised Mensch as a skillful designer and engineer
The original 6502 manufactured in 1975 contained 3510 transistors and 1018 depletion-load pullups, in a die that was 0.168 inches × 0.183 inches (≈ 4.27mm × 4.65mm), produced on a 3” silicon wafer. The process used to create the 6502 was the N-channel Silicon Gate Depletion 5 Volt Process, aka the “019” process. Developed at MOS Technology by Terry Holdt, it required seven photomasks, and consisted of approximately 50 steps to produce these layers :-
The MOS Technology 6502 Microprocessor 1975 - "The 8-Bit Guy" Video
At MOS Technology
MOS Technology, was a scrappy little integrated circuit manufacturer located near Valley Forge, Pennsylvania. Mensch says this, “The environment was a small company where Mort Jaffe, John Paivinen, Don McLaughlin, the three founders had created small teams of very capable calculator chip and system designers, a quick turn around mask shop and a high yielding large chip manufacturing team out of TI. So you go from Motorola with, relatively speaking, an unlimited budget for design and manufacturing, to an underfunded design team with very limited design tools for logic and transistor simulation. We had to manually/mentally simulate/check the logic and use very limited circuit simulation. In other words, it was really low budget. The datasheets and all documentation was done by the design team.”, , Peddle persuaded Mensch and six other Motorola engineers, Harry Bawcom, Ray Hirt, Terry Holdt, Michael Janes, Wil Mathys, and Rod Orgill to join him and a few others at MOS in designing and producing what became the MCS 6501/6502 chipset. Mensch goes on “At MOS John Paivinen, Walt Eisenhower, and Don Payne, head of the mask shop, and mask designer Sydney Anne Holt completed the design and manufacturing team that created the high yielding NMOS depletion mode load process,” says Mensch. “The result was the MCS 6501/6502, 6530/6532 Ram, ROM Timer and IO combo and 6520/6522 PIA/VIA microprocessor family.”
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IN-AP Systems - Established 1997
A computer is like the mind, it has IN-finite AP-plications. . .
