Question

Write a general example of interrupts in C language with comments. Thank you

Answer 1

Answer:-

• Interrupts are messages to the Pentium chip to halt it current activity, and perform our requested job.
• We can almost do anything using interrupts without using functions.
• Note below example – we haven’t used printf() still we are able to print message on screen.

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program:

#include<dos.h>

void main() {

   char *message = "Pritesh Taral$";

   _AH = 9;

   _DX = (int) message;

   geninterrupt(0x21);

}

output:-

Prtesh Taral

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Explanation of program:-

#include<dos.h>

• dos.h header file contain geninterrupt() function which is used to create interrupt.
• geninterrupt(0x21) is used to generate 0x21 interrupt.
• Note that the sentence is ended with a ‘$’ which is a terminating character.
• geninterrupt(0x21) means that we want to generate the 0x21 interrupt.
• The ‘0x’ prefix is given which tells that the number is in hexadecimal.
• There are many interrupts, each having its own unique number

_AH = 9

• We want to fill the register AH with integer 9.
• Register is actually a memory location inside your Pentium chip.

_DX=(int)message

• We are storing the address of the message to register DX.