OS PROGRAM 7

Timer Interrupt Program - C

#include <dos.h>
#include <conio.h>
#include <stdio.h>

volatile unsigned long count = 0;

void interrupt (*oldhandler)();

void interrupt newhandler()
{
    count++;

    /* Execute the original timer interrupt */
    oldhandler();
}

int main()
{
    clrscr();

    /* Get the original timer interrupt handler */
    oldhandler = getvect(0x08);

    /* Install our new timer interrupt handler */
    setvect(0x08, newhandler);

    gotoxy(10, 10);
    printf("Timer Interrupt Program");

    gotoxy(10, 12);
    printf("Press any key to stop...");

    while (!kbhit())
    {
        gotoxy(10, 14);
        printf("Timer Count = %lu   ", count);
    }

    /* Read the pressed key */
    getch();

    /* Restore the original timer interrupt */
    setvect(0x08, oldhandler);

    gotoxy(10, 16);
    printf("Timer interrupt restored.");

    getch();

    return 0;
}