ZDU Digital UART ICs Zilog ZDU Digital Universal Asynchronous Receiver/Transmitter (UART) ICs provide full duplex asynchronous communications with a 128B FIFO (First In, First Out) buffer. The FIFO buffer allocates 64 bytes each to the Receive and Transmit operations. These Zilog CMOS communications devices also contain a 4KB EEPROM and General Purpose Input and Output (GPIO) with programmable interrupt capability. ZDU Digital UARTs feature an internal 8MHz oscillator, eliminating the need for external crystal oscillators. The user controls the digital UART by the I2C protocol (2-Wire Interface). Up to eight devices are allowed in the same I2C network. These fully programmable UART ICs are preconfigured to operate at a 57.6kb/s rate so configuration is not required to access the UART or the EEPROM. Zilog ZDU Digital UART ICs provide separate programmable interrupts and interrupt lines for UART notification and GPIO notifications. These separate interrupts and interrupt lines mean the controlling device does not have to poll the UART ICs for data.