What is asynchronous and synchronous data transmission?
Asynchronous data transmission:
In asynchronous transmission, data is transmitted character-by-character. Data is not saved before transmitting. It was commonly used in teletype communications. As a user types a character on the keyboard, it is immediately transmitted. The time interval between two characters is not fixed. There may be gaps between characters being transmitted. This data transmission method is very slow.
In synchronous transmission, data is transmitted block-by-block or word-by-word. Each block- may contain several bytes of data. The time interval between two characters is same. In this mode, data is saved before transmitting. No start and stop bits are used. It uses clock signals to schedule or control the transmission of information.