2’s Complement of a Number Assembly Language

 

Write a Program to find the 2’s Complement of number given by the user . Program should load number into register and then find 2’s Complement of Number .

Algorithm behind the 2’s Complement is given below and based on this strategy you can easily implement 2’s Complement program in Assembly Language .

Algorithm for 2’s Complement of Number:

 

Step I : Initialize the data memory.

Step II : Load the number in AX.

Step III : Find 2’scomplement of number.

Step IV : Display the result.

Step V : Stop.

Flow Chart

Program for 2’s Complement : 

 

.model small                                          
 .data  
 a dw 1234H  
 .code  
      mov      ax, @data          ; Initialize data section       
      mov      ds, ax  
      mov      ax, a              ; Load number1 in ax                             
      neg      ax                 ; find 2's compement. Result in ax  
      mov      ch, 04h            ; Count of digits to be displayed  
      mov      cl, 04h            ; Count to roll by 4 bits  
      mov      bx, ax             ; Result in reg bx  
 l2:     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  
 l4:     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

 

How to Run this Program :

 

For Running this program you should have installed Tasm on you computer .

Find 1’s complement of a number

 

Algorithm for finding 1’s Complement

 

Step I : Initialize the data memory.

Step II : Load the number in AX.

Step III : Initialize counter = 16.

Step IV : Rotate number by 1 bit position to left with carry.

Step V : Complement carry.

Step VI : Decrement counter.

Step VII : Check if count = 0. If yes, go to step VIII else goto Step IV.

Step VIII : Rotate number by 1 bit position to left with carry to restore original carry back.

Step IX : Display 1’s complement.

Step X : Stop.

Program Code 1’s complement of a number:

.model small

.data

a dw 1234H

.code

mov ax, @data           ; Initialize data section

mov ds, ax

mov ax, a               ; Load number1 in ax

mov cx, 16              ; Load CX with count

up : rcl ax, 1          ; Rotate ax by 1bit to left with carry

cmc                     ; find 1's complement of bit

loop up                 ; check if all bits complemented, if not goto up

rcl ax, 1               ; return carry back to original position

mov ch, 04h             ; Count of digits to be displayed

mov cl, 04h             ; Count to roll by 4 bits

mov bx, ax              ; Result in reg bx

l2: 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

l4: 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

 

Mask Upper Nibble

 

Write assembly programs to Mask Upper Nibble for that number should be loaded into the register and operation should be implemented on that loaded number .

• Calculated result should be displayed in the output .

Algorithm for Mask Upper Nibble:

Step I : Load the number in AL.

Step II : Mask the upper nibble.

Step III : Display result.

Step IV : Stop.

Program for Mask Upper Nibble:

 

 

 

 

.model small                           
 .data  
 a dw 0012H  
 .code  
      mov      ax, @data          ; Initialize data section  
      mov      ds, ax                                                                 
      mov      ax, a               ; Load number1 in ax  
      and      al, 0fh               ; mask upper nibble.Result in al  
      mov      ch, 02h          ; Count of digits to be displayed  
      mov      cl, 04h          ; Count to roll by 4 bits  
      mov      bh, al               ; Result in reg bh  
 l2:     rol      bh, cl               ; roll bl so that msb comes to lsb   
      mov      dl, bh               ; 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  
 l4:     add      dl, 30H  
      mov      ah, 02               ; Function 2 under INT 21H (Display character)  
      int      21H  
      dec      ch               ; Decrement Count  
      jnz      l2  
      mov      ah, 4ch  
      int      21h  
      end

 

Assembly programs