Andy:
my cpu is working, i can toggle the LED through the port1. and from scope see, WR, RD, CLK signals are no problem. and execute the exactly times write and read command...

Dan:
I have not used software and hardware flow control... I used it very simple.

initialize the uart and check LSR bit6, if it is set, I will send next byte again, but the bit6 is always 0.. meanwhile I get wrong result from internal loopback test... Do you have any idea about uart test?

Thanks.

Frank