ot? Simulate something....

Hey all! I am beginning to write a simulator for a "microcomputer", it will feature a curses (terminal) front panel. it will be a 12 bit machine. You will be able to issue commands to the simulator without stopping the program (for mounting virtual paper tapes, printing to files etc) Shown on the front panel will be a switch register, an Accumulator and the program counter (all 12 bit) a "running" light and a Overflow light. Insert = sw -> pc home = sim command Pgup = examine ([pc] -> sw delete = (deposit) sw ->[pc] end = halt pgdn = run Obviously a 12 bit computer suggests a PDP-8, but the function keys are going to be the "bit flip" front panel keys and they are grouped in three sets of four. I am not against a PDP-8 but it's instruction set is better expressed in octal right? Were there any other 12 bit computers? preferably with Hex friendly instruction sets? Operational choices - should examine increment PC?, should deposit? I am open to other meanings of the operation keys... they are arranged as above on my thinkpad. The program will be written in C.