DESCRIPTION
The Epic Ei88C681/Ei68C681 DUART Dual Universal Asynchronous Receiver and Transmitter is a data communication device that provides two fully independent full duplex asynchronous communication channels in a single package. The DUART is designed for use in microprocessor based systems and may be used in a polled or interrupt driven environment.
   
FEATURES
• Full duplex, dual channel asynchronous
    receiver and transmitter
• Quadruple-buffered receiver and transmitter
• Stop bits programmable in 1/16-bit increments
• Internal bit rate generator with 23 bit rates
• Independent bit rate selection for each Rx
    and Tx
• 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
• Interrupt output with 8 maskable interrupting
    conditions
• Interrupt vector output on acknowledge
• Programmable interrupt daisy chain
• Up to 15 I/O pins (depending on package
    and version)
• Multidrop mode compatible with 8051 ninebit mode
• On-chip oscillator for crystal
• Stand-by mode to reduce operating power
• Advanced CMOS low power technology