DESCRIPTION
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.

FEATURES
• Full duplex, four channel asynchronous  receiver and transmitter
• Quadruple-buffered receiver and transmitter
• Internal bit rate generator with 23 industry  standard bit rates operating from either of  two standard crystal clocks
• Independent bit rate selection for each  receiver and transmitter
• Maximum bit rate: 1 x clock - 2 Mb/sec., 16  x clock- 250 Kb/sec.
• Normal, auto-echo, local loop-back and  remote loop-back modes
• Multi-function 16-bit counter/timer
• Programmable interrupt daisy chain
• Up to 32 I/O pins (depending on package  and version)
• Change of state detectors on inputs
• Multidrop mode compatible with 8051 ninebit mode
• Stop bits programmable in 1/16-bit increments
• Pin selectable 88xxx/68xxx interface
• Debounced reset pin (20 nsec. min)
• On-chip oscillator for crystal
• Programmable internal clock:X1/CLK or X1/CLK divided by 2
• Buffered system clock output pin
• Stand-by mode to reduce operating power
• Advanced CMOS low power technology