بیا اینم یه مثال:
#define ON (1)
#define OFF (0)
//Turn speaker on or off. */
void ChangeSpeaker(int status)
{
int portval;
portval = inportb( 0x61 );
if ( status==ON )
portval |= 0x03;
else
portval &=~ 0x03;
outportb( 0x61, portval );
}
void Sound(int hertz)
{
unsigned divisor = 1193180L / hertz;
ChangeSpeaker( ON );
outportb( 0x43, 0xB6 );
outportb( 0x42, divisor & 0xFF ) ;
outportb( 0x42, divisor >> 8 ) ;
}
void NoSound( void )
{
ChangeSpeaker( OFF );
}
int main( void )
{
Sound( 355 );
delay( 1000 );
NoSound( );
return(0);
}