Arithmetic Operations in 8086 Assembly Language

So, to learn any programming language. It’s necessary for us to know, about how to do basic operations on numbers.

Such as Addition, Subtraction, Division and Multiplication. These are the 4 things that come to our mind, when we think of numbers and, operations on them.

Photo by Antoine Dautry on Unsplash

So, today I am going to show you the code, on how to do Arithmetic operations on two given numbers using Assembly Language and explain it.

Code →

.model small
.data
    n1 dw 0006h
    n2 dw 0003h
    addn dw ?
    subt dw ?
    mult dw ?
    divn dw ?
.code
    mov ax,@data
    mov ds,ax
    mov ax,n1
    add ax,n2
    mov addn,ax
    mov ax, n1
    sub ax,n2
    mov subt,ax
    mov ax,n1
    mul n2
    mov mult,ax
    mov ax,n1
    div n2
    mov divn,ax
mov ah,4ch
int 21h
end

Explanation →

.data
    n1 dw 0006h
    n2 dw 0003h
    addn dw ?
    subt dw ?
    mult dw ?
    divn dw ?

Here, n1 and n2 are two variables, which contain two 16-bit numbers, i.e. 0006h & 0003h respectively. And, addn, subt, mult, divn are variables which will contain the results of addition, subtraction, multiplication and division respectively.

mov ax,n1
add ax,n2
mov addn,ax

In the above code snippet, n1 is stored in the 16-bit accumulator register ax. And, the contents of n2 are added to ax . Finally, the result present in ax is moved to the variable addn .

mov ax, n1
sub ax,n2
mov subt,ax

Similar to the previous explanation, here also the same steps follow. But at last, the result is stored in the variable subt .

mov ax,n1
mul n2
mov mult,ax

Multiplication operation is slightly different from Addition & Subtraction. Here, first n1 is moved to ax . And, then we do mul n2 : In this operation multiplication of a given operand is always done with the accumulator register. It actually means this mul accumulator, operand(or variable) . But, the accumulator register ax is told implicitly, it’s not given specifically for mul operation. And, the multiplication result is also stored in ax , which is again stored back in the mult variable.

mov ax,n1
div n2
mov divn,ax

The division code snippet is given as above. It also follows the same rule as multiplication. i.e. division happens implicitly with the ax register. And, then the result is being moved from ax to divn variable.

And, that’s the end of my explanation for this code. So if, you liked the code and it’s explanation, feel free to give me a clap 👏. And if you still have more doubts, drop them in the comments section, and I will do my best to answer them.