void beeperOn(unsigned frequency) { io_wr(0x43, 0xB6); frequency = 1193180u / frequency; io_wr(0x42, frequency & 0xFFu); io_wr(0x42, frequency >> 8); io_wr(0x61, io_rd(0x61) | 3); } void beeperOff(void) { io_wr(0x61, io_rd(0x61) & ~3); }