Hello Aiping,
How did you read the code from the MC68705R3 in the first instance? If you used a Motorola Evaluation Module for the device, there is a built-in (non-symbolic) disassembler accessed using the ASM command. The disassembled output can be captured to a file, using a standard terminal program.
Once you have done the dissassembly, there is still a substantial amount of work required to symbolically identify all the I/O, registers and labels, and to comment the operation of the code.
Regards,
Mac
Message Edited by bigmac on 03-15-200612:25 AM