Write a program to Subtract Two 16 Bit Numbers in Assembly language . Program logic should ask for two numbers to be substrated and the should implement required logic to the numbers to get desired output.
Consider that a word of data is present in the AX register and second word of data is present in the BX register.
We have to subtract the word in BX with the word AX. Please find more Assembly language codes on this page.
Using subtract (SUB) instruction, subtract the contents of two registers.
Result will be stored in the AX register.
Display the result using display routine.
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AX = 1234 H
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1234 H
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BX = 0100 H
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–
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0100 H
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1134 H
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Algorithm to Subtract Two 16 Bit Numbers :
Step I : Initialize the data segment.
Step II : Get the first number in AX register.
Step III : Get the second number in BX register.
Step IV : Add the two numbers.
Step V : Display the result.
Step VI : Stop
Program to Subtract Two 16 Bit Numbers :
.model small
.data
a dw 1234H
b dw 0100H
.code
mov ax, @data ; Initialize data section
mov ds, ax
mov ax, a ; Load number1 in ax
mov bx, b ; Load number2 in bx
sub ax, bx ; subtract numbers. 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 . If you have not installed Tasm yet please install from Here .
C:\programs>tasm 16-sub.asm
Turbo Assembler Version 3.0 Copyright (c) 1988, 1991 Borland International
Assembling file: 16-sub.asm
Error messages: None
Warning messages: None
Passes: 1
Remaining memory: 438k
C:\programs>tlink 16-sub.obj
Turbo Link Version 3.0 Copyright (c) 1987, 1990 Borland International
Warning: No stack
C:\programs>16-sub
1134
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