Ricoh 2A03
From FamiWiki
The Ricoh 2A03 is an 8-bit microprocessor manufactured by Ricoh for the Nintendo Family Computer and Nintendo Entertainment System.
Technical Details
The Ricoh 2A03 contains a second-sourced MOS Technology 6502 core, modified to disable the 6502's BCD mode (Likely to avoid a MOS Technology patent).
