I mean after executing a code on hex by ASSEM or KEIL it should increment +1 (e.g. 0000,0001,0002,0003,...) decremnt -1 (0019,0018,0017....),increment +10 (0001,0010,0020,0030,0040...) decrement -10 (0040,0030,0020,0010...) and clear it turn it to previous state (if a inciallization state was 0000 then it should clear registers and turn to this state).
a communication between pc and motherboard is serial communication (RS232) DATA CABLE.
increment and decrement on 7 seg display should be inicialized from 5 keys on keyboard ( e.g. CTRL +1,ALT -1,TAB +10,SHIFT -10 AND DEL clear and previous state)