assembly language (visual studio)

0 .data firstMsg secondMsg hexDigi hexDig2 hexSum BYTE BYTE BYTE BYTE BYTE "Enter first hex digit: ",0 "Enter second hex digit: ? ? ? .code main PROC ;Start call clrscr ; Print "Enter first hex digit: " ; Input hexDigi ; Print "Enter second hex digit: ; Input hexDig2 hexSum = hexDigi + hexDig2 ; Print "Hex Sum =", hexSum exit ENDP ; Stop main ; Input hex digit ; Input: none ; Output: hex digit returned in AL Enter inHex PROC ; input hexDigit ret inHex ENDP ;Exit ; Print hex digit ; Input: value to print in AL register ; output: none ; out Hex PROC ; Print hexDigit ret out Hex ENDP ;Enter ;Exit END main