ADuC842 Firmware Upload

Hello,

I am just becoming familiar with the ADuC842.  To speed things up I am hoping someone can instruct me on how I might be able to upload the firmware off of a device that is already programmed.  I am supporting a customer and have 2 systems that act differently.  I suspect the firmware is different.   If I can retrieve the firmware from each unit I should be able to perform a bit/bit comparison.  

Thanks in advance

Robert