The 6309 is Hitachi's version of the Motorola 6809 microprocessor. Compatible with the 6809, it added two new eight-bit registers that could be added to form a second 16-bit register, and all four eight-bit registers could form a 32-bit register. It also featured division, and some 32-bit arithmetic and was generally 30% faster in native mode. Surprisingly, this information was never published by Hitachi.
Based on material from FOLDOC, used with permission.