The marlin Software is prepared to control more than 1 extruder and the K8200 firmware is targeted to the board 77 that has already definitions to have a second extruder. Configuration.h needs therefore be edited to tell that there are 2 extruders.

However the hardware is not prepared for that. The hardware could be expanded to allow a second extruder. A difficulty is finding the new pins. pin.h defines the pin numbers used by the software. Sd2pinMap.h then maps them to the specific microprocessor used. Finally the marlin software uses fastio.h to access it. Analog inputs used for the temperature sensors are handled differently. Since they use featured pins they can not be mapped to other ports as a simple digital IO. The ATmega processor has 16 analog input pins. 0 to 7 are on port F and 8 to 15 are on port K. This results in the following: