Synchronous And Asynchronous Operations

Sequential circuits are divided into two main types :-

1.Synchronous

2.Asynchronous

• The send, receive, and reply operations may be synchronous or asynchronous. A synchronous operation blocks a process till the operation completes. An asynchronous operation is non-blocking and only initiates the operation. 

• In the case of synchronous operation, a transfer of data from one point to another is assumed to occur within a fixed time interval known to both the sending and receiving devices. The sender and receiver are synchronized by a signal called the clock, which may be supplied externally to both, or generated by the sender with the data, and occasionally incorporated within it, but often sent on a separate signal line. In the case of asynchronous operation, the sending device or circuit need have no knowledge of the time-scale on which the receiver (and intervening connection) operates, but rather transmits its data with a "data ready" signal and then awaits a reply to the signal sent. Upon receipt of the reply by the sender, it removes its original data and status signal from the line, often (but not necessarily) waiting for the removal of the reply by the sender before proceeding with a second transfer.