The SC16C550B is a Universal Asynchronous Receiver and Transmitter (UART) used for serial data communications. Its principal function is to convert parallel data into serial data, and vice versa. The UART can handle serial data rates up to 3 Mbit/s. The SC16C550B is pin compatible with the ST16C550, TL16C550 and PC16C550, and it will power-up to be functionally equivalent to the 16C450. The SC16C550B also provides DMA mode data transfers through FIFO trigger levels and the TXRDY and RXRDY signals. On-board status registers provide the user with error indications, operational status, and modem interface control. System interrupts may be tailored to meet user requirements. An internal loop-back capability allows on-board diagnostics.