UART / Universal asynchronous receiver/transmitter is a microchip with programming that controls a computer's interface to attached serial devices. A UART / Universal Asynchronous Receiver/Transmitter chip provides computers with the RS-232C Data Terminal Equipment (DTE) interface, in order to communicate and send (as well as receive) data between modem or other serial devices.
Converts the bytes it receives from the computer along parallel circuits into a single serial bit stream for outbound transmission