Digital sequential logic circuits are divided into synchronous and asynchronous types. Communication channels may be either synchronous or asynchronous. Standby servers can be synchronous or asynchronous. HDLC frames can be transmitted over synchronous or asynchronous serial communication links. An IPC mechanism is either synchronous or asynchronous. Applications need not be exclusively synchronous or asynchronous. Both synchronous and asynchronous transmissions are supported by the standard. The consensus problem may be considered in the case of asynchronous or synchronous systems. There are two versions of this analysis&colon; synchronous and asynchronous. The problem has been studied in the case of both synchronous and asynchronous communications. This is similar to the approach used in Bidirectional-streams Over Synchronous HTTP (BOSH). Induction generators operate by mechanically turning their rotors faster than synchronous speed. Various options for synchronous multi-master replication exist. This can be overcome by using a synchronous interface. FOC is used to control AC synchronous and induction motors.