Editing 16550 UART (section)

{{Short description|Integrated circuit serial port implementation}}
{{Use dmy dates|date=February 2020|cs1-dates=y}}
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[[Image:Exar16550onItronixPCB.jpg|thumb|[[Exar Corporation|Exar]] 16550]]

The '''16550 UART''' ([[universal asynchronous receiver-transmitter]]) is an [[integrated circuit]] designed for implementing the interface for [[serial communications]]. The corrected -A version was released in 1987 by [[National Semiconductor]].<ref name="Michael_1987"/> It is frequently used to implement the [[serial port]] for [[IBM PC compatible]] personal computers, where it is often connected to an [[RS-232]] interface for modems, serial [[Computer mouse|mice]], printers, and similar peripherals. It was the first serial chip used in the [[IBM PS/2]] line, which were introduced in 1987.<ref name="upgrpc"/><ref name="Gilluwe_1997"/><ref name="Paul_2002_CTMOUSE"/>

The part was originally made by National Semiconductor. Similarly numbered devices, with varying levels of compatibility with the original National Semiconductor part, are made by other manufacturers. A UART function that is register-compatible with the 16550 is usually a feature of multifunction I/O cards for IBM PC-compatible computers and may be integrated on the motherboard of other compatible computers.

Replacement of the factory-installed [[8250 UART]] was a common upgrade for owners of IBM PC, XT, and compatible computers when high-speed modems became available. Above 9600 baud, owners discovered that the serial ports of the computers were not able to handle a continuous flow of data without losing characters. Exchange of the 8250 (having only a one-byte received data buffer) with a 16550—and occasionally patching or setting system software to be aware of the [[FIFO (computing and electronics)|FIFO]] feature of the new chip—improved the reliability and stability of high-speed connections.