The SC16C554B/554DB is a 4-channel Universal Asynchronous Receiver and Transmitter (QUART) 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 5 Mbit/s. It comes with an Intel or Motorola interface. The SC16C554B/554DB is pin compatible with the ST16C554 and TL16C554 and it will power-up to be functionally equivalent to the 16C454. Programming of control registers enables the added features of the SC16C554B/554DB. Some of these added features are the 16-byte receive and transmit FIFOs, four receive trigger levels. The SC16C554B/554DB 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.