1975 · Low-Cost 8-Bit Microprocessor · Work 890 of 1,871
A hotel suite in San Francisco turned into a trade fair stand, on a table under a white linen cloth two large clear glass preserving jars with plain metal screw lids, filled to the brim with hundreds of small dark chips with two rows of silver legs, every chip plain smooth and unmarked, an open grey cash box, a woman's hand in a patterned dress sleeve reaching in from the left edge and dropping one chip into an open hand in a dark suit sleeve reaching in from the right edge, both people outside the frame, a patterned red and gold carpet, tall windows with heavy curtains, warm light from a crystal chandelier.
What it was used for
An 8-bit processor from MOS Technology, sold to engineers and hobbyists. CPU Shack and The Chip Letter report the same episode: at WESCON on 16 September 1975 in San Francisco sales on the show floor were forbidden, so Chuck Peddle sent visitors to a hotel room across the road, where the chip cost 25 USD; the 6501 was meant to sell for 20 USD. CPU Shack writes that jars of chips were displayed to suggest full production while the bottoms of the jars held defective parts. Intel's 8080 and Motorola's 6800 then cost about 175 to 200 USD per All About Circuits. The 6502 was later used in the Apple I and II, Commodore PET, VIC-20 and C64, the Atari 2600 (as the 6507), the NES (a Ricoh derivative) and the BBC Micro.
What was new
What it could do: per All About Circuits the same work with about 4,500 transistors, 25 to 40 percent fewer than its rivals (The Chip Letter gives 3,500 against 4,100 for the 6800), hence smaller dies and lower cost per wafer - 25 USD instead of about 175. CPU Shack names the process as 8 µm depletion-load NMOS against the 6800's 6 µm enhancement process. The 6501 was pin-compatible with the Motorola 6800 but had a different instruction set; the 6502 used nearly the same mask set, brought the oscillator on chip and differed slightly in pinout. "First cheap microprocessor" would overstate it: CPU Shack stresses that the 6501 to 6505 were developed concurrently and that the 6502 was not a forced redesign.
What the sources leave open: The sting is well documented: The Chip Letter quotes a December 1975 report in Microcomputer Digest on Motorola's suit in Philadelphia; MOS paid 200,000 USD, dropped the 6501, returned documents its engineers had taken and cross-licensed patents - the 6501 was designed, built and advertised but never sold. Motorola cut the 6800 from 175 to 69 USD. No source gives production figures.