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When Nintendo used the 6502 core in the NES (as part of the Ricoh 2A03/2A07 microprocessor and sound generator), they circumvented the 6502's patent protection by disabling the BCD arithmetic. As a result, Commodore -- holders of the 6502 patent after they bought MOS Technology -- did not receive any payments for the use of the core.

Later, Nintendo used the 65816 core in the Ricoh 5A22 that powered the SNES. Did they pay WDC, who developed the 65816, for this, or did they find a similar loophole?

  • This is an aside to the question - but how in the 1980s was it seen fit to award a patent for having BCD arithmetic? – another-dave May 21 at 23:40
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    It was the 1970s and it wasn't for BCD arithmetic in general, it was for a BCD implementation without a performance penalty. patents.google.com/patent/US3991307A/en – Kelvin Sherlock May 22 at 1:25
  • Wikipedia claims the SNES CPU was based on the CMD/GTE 65c816, which was itself based on the WDC chip. Following that logic, they would have had to pay GTE rather than WDC. – tofro Jul 27 at 21:15
  • @tofro Either way, it would still be based on WDC IP, so the question still stands: Did money flow from Nintendo to WDC, either directly or through CMD / GTE? – Michael Graf Jul 31 at 13:48

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