The XR16M5641 (M564) is an enhanced quad Universal Asynchronous Receiver and Transmitter (UART) with 32 bytes of transmit and receive FIFOs, programmable transmit and receive FIFO trigger levels, automatic hardware and software flow control, and data rates of up to 16 Mbps at 4X sampling rate. Each UART has a set of registers that provide the user with operating status and control, receiver error indications, and modem serial interface controls. An internal loopback capability allows onboard diagnostics. The M564 is available in a 48-pin QFN, 64-pin LQFP, 68-pin PLCC and 80-pin LQFP packages. The 64-pin and 80-pin packages only offer the 16 mode interface, but the 48 and 68 pin packages offer an additional 68 mode interface which allows easy integration with Motorola processors. The XR16M564IV (64-pin) offers three state interrupt output while the XR16M564DIV provides continuous interrupt output. The XR16M564 is compatible with the industry standard ST16C554 and ST16C654/ 654D.