timer60hzCallback method
Implementation
void timer60hzCallback(Timer _) {
if (_chip8.soundTimer > 0) {
_chip8.soundTimer--;
if (_chip8.soundTimer == 0) _sendPort.send(Chip8StopSoundEvent());
}
if (_chip8.delayTimer > 0) _chip8.delayTimer--;
_sendPort.send(_chip8.display);
}