The Epic Ei68C684/Ei88C684 Quad Universal Asynchronous Receiver and Transmitter (QUART) is a data communication device that provides four fully independent full duplex asynchronous communication channels in a single package. The QUART is designed for use in microprocessor based systems and may be used in a polled or interrupt driven environment. Two basic versions of the QUART are pin selectable with SEL pin and each is optimized for use with various microprocessor families: the Ei88C684 for 8080/5, 8086/88, Z80, Z8000, 68XX and 65XX family based systems., and the 68C681 for 68000 family based systems.and the Ei68C684 for 68000family based systems A programmable mode of the Ei88C684 versions provides an interrupt daisy chain for use in Z80 and Z8000 based systems. The bus interfaces are however general enough to allow interfacing with other microprocessors and microcontrollers. The Ei88C684 and Ei68C684 are high integrated versions of Epic Semiconductor's Ei88C681 and Ei66C681 DUART's respectively, and are function compatible with those devices.