Software Interrupts

Software in are used by programs to request system services

These interrupts are treated in the same way as the interrupts for the Hardware devises are\

In assembly we useINT instruction to perform such interruptsSyntax: name INT interrupt-number;commentsSyntax (simplified): INT interrupt-number Example: INT 21h


These interrupts are used with there functions

Explanation

In order to use I/O operations we use interrupt 21h,
But in order to perform a specific task, like printing a string to a standard output devicewe have to use its function 09h

Example code

MOV AH 09h
LEA DX, string
INT 21h