8086

<!--Obj 3 - Gray code-->

MOV AX, 0000H
MOV DS, AX
MOV AL, [3000H]
MOV BL, AL
SHR AL, 01H
ROR BL, AL
MOV [3001H], BL
HLT
    

<!--OBJ 4: 2'S COMPLIMENT-->

MOV AX, 0000H
MOV DS, AX
MOV AL, [2000H]
NOT AL
ADD AL, 01H
MOV [2001H], AL
HLT
    

<!--OBJ 2A: SWAPPING OF NIBBLE OF DATAS-->
MOV AX, 0000H
MOV DS, AX
MOV AL, [2000H]
MOV AL, [SI] 
ROR AL, 04H
INC SI 
MOV [SI], AL
HLT
    

<!--OBJ 2B - USING THE SAME DATA PROGRAMMING FUNCTION Y.-->
MOV AX, 0000H
MOV DS, AX
MOV AL, [2000H]
MOV AL, [SI] 
ROR AL, 04H
INC SI 
MOV [SI], AL
MOV BL, [2003H]
MOV CL, AL
AND AL, BL
ROR CL, BL
OR AL, CL
MOV [2004H], AL
HLT
    

<!--OBJ 4: 2'S COMPLIMENT-->