Don't support related addressing from PC register!
Sample:
IN R0,00H
IN R1,00H
ADD R0,R1
OUT 40H,R0
HLT
Result:
00 20 ; IN R0,00H
01 00
02 21 ; IN R1,00H
03 00
04 04 ; ADD R0,R1
05 30 ; OUT 40H,R0
06 40
07 50 ; HLT
Destination register first, then the Source register!