16550 UART

Similarly numbered devices, with varying levels of compatibility with the original National Semiconductor part, are made by other manufacturers.

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 feature of the new chip—improved the reliability and stability of high-speed connections.

The 16550 also incorporates a transmit FIFO, though this feature is less critical as delays in interrupt service would only result in sub-optimal transmission speeds and not actual data loss.