I agree with Blinx123.. more or less
C65 Rev 5 was quite a complete machine... very near to launch... Of course latest ROM revision had some unimplemented commands. C65 was sent to all Commodore departments to do final testing and package was completed with some instructions for use it. Commodore didn't want a full - C64 - compatible machine: they wished 70 - 80 % of compatibility in C65 mode and 100% in C64 emulation inside the machine (with Go 64 command in C65 mode you can turn in C64 emulation mode)
Take care, Carlo