A common benefit of an instant-on and stable high-speed oscillator is response to serial communication. For example, the clock source for the UART must start and be stable instantly to prevent received characters from being lost. If a slow or 2-speed oscillator is used, the first character in the received and the data stream is lost. Also, instant-on saves power as the system does not have to waste energy waiting for oscillator startup allowing events to be serviced immediately.