An assembly language program to add two 16 bit BCD numbers :-

Add Two 16 Bit BCD Numbers Algorithm :-

Step I : Initialize the data memory.

Step II : Load the first number into AX register.

Step III : Load the second number into BX register.

Step IV : Add two lower digits.

Step V : Adjust result to valid BCD number.

Step VI : Store the result in BL.

Step VII : Add the two upper digits with carry.

Step VIII : Adjust result to valid BCD number.

Step IX : Store the result in BH.

Step X : Display the result.

Step XI : Stop.

16 Bit BCD Numbers Program

 .model small  
 .data  
 a dw 3629H  
 b dw 4738H  
 .code  
     mov  ax, @data  ; Initialize data section  
     mov  ds, ax  
     mov  ax, a      ; Load number1 in ax  
     mov  bx, b      ; Load number2 in bx  
     add   al, bl      ; add lower two digits. Result in al  
     daa            ; adjust result to valid bcd  
     mov  bl, al      ; store result in bl  
     adc   ah, bh         ; add upper two digits. Result in ah  
     mov  al, ah      ; al=ah as daa works on al only  
     daa            ; adjust result to valid BCD  
     mov  bh, al     ; store result in bh           
     mov  ch, 04h    ; Count of digits to be displayed  
     mov  cl, 04h    ; Count to roll by 4 bits  
  rol    bx, cl     ; roll bl so that msb comes to lsb  
     mov  dl, bl      ; load dl with data to be displayed  
     and   dl, 0fH    ; get only lsb  
     cmp  dl, 09     ; check if digit is 0-9 or letter A-F  
     jbe   l4  
     add   dl, 07     ; if letter add 37H else only add 30H  
   add   dl, 30H  
     mov  ah, 02         ; Function 2 under INT 21H (Display character)  
     int    21H  
     dec   ch        ; Decrement Count  
     jnz   l2  
     mov  ah, 4cH    ; Terminate Program  
     int    21H  
     end