.MODEL SMALL .STACK 100H .DATA PROMPT_1 DB \'Enter the First digit : $\' PROMPT_2 DB \'Enter the Second digit : $\' PROMPT_3 DB \'Difference of First and Second digit : $\' .CODE MAIN PROC MOV AX, @DATA ; initialize DS MOV DS, AX LEA DX, PROMPT_1 ; load and display the PROMPT_1 MOV AH, 9 INT 21H MOV AH, 1 ; read a character INT 21H MOV BL, AL ; save First digit in BL in ASCII code SUB BL, 30H MOV AH, 2 ; carriage return MOV DL, 0DH INT 21H MOV DL, 0AH ; line feed INT 21H LEA DX, PROMPT_2 ; load and display the PROMPT_2 MOV AH, 9 INT 21H MOV AH, 1 ; read a character INT 21H MOV BH, AL ; save Second digit in BH in ASCII Code. SUB BH, 30H MOV AH, 2 ; carriage return MOV DL, 0DH INT 21H MOV DL, 0AH ; line feed INT 21H LEA DX, PROMPT_3 ; load and display the PROMPT_3 MOV AH, 9 INT 21H SUB BL, BH ; subtract First and Second digit ADD BL, 30H ; convert ASCII to DECIMAL code MOV AH, 2 ; display the character\\digit MOV DL, BL INT 21H MOV AH, 4CH ; return control to DOS INT 21H MAIN ENDP END MAIN