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* gotc.bat    : batch file for use TC 2.0
* gomsc.bat   : batch file for use MSC 5.0/6.0 
* demo3.prj   : project file for TC++3.0 or BC++ 3.1
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1. 2*RS-485
2. interrupt drivern driver
3. driver provide 1K QUEUE for every COM
4. read QUEUE status, if there is any input --> echo back to the smae COM port
5. the program will control the direction of RS-485 to receive/transmit data