Question

what is the essential difference between asynchronous and synchronous signals? 

Answer 1

Signals are not asynchronous and synchronous but these are completely different type or say methods of transmission synchronization of signals known as synchronous data transfer ans asynchronous data transfer.

In synchronous data transfer mode both the sender and reciever shares a common clock or master clock which is sent by the sender as a signal which tells the reciever whene the message signal is valid and when its not.

Whereas in asynchronous data transfer theres nothing like a clock shared by sender and reciever.So, the sender and the receiver first decides to agree on a speed on which the data will be transfered. When the transfer of the data starts then the data usually remains constant. Internal circuits are set by both sender and reciever so that data accessing follows the required agreement.

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