No handsake serial and windows bugs

Testing my serial port , I have a windows 10 bug with terra term.
The keyboard keeps echoing to the screen. It looks like some sort of
loop back is set on the windows uart. This happens when powered up
but the 6850 is reset and the test software is halted. The test program
is just " while(1) putch(getch())" and that works fine. Local echo is off
on terra term.
Press of key “A”
Displays “AA” when the test program is running
Displays “A” when the test program is halted

Has any one seen this kind of problem?

How about incrementing the char before sending it back? Might help see what’s going on

Defective max232A was one of my problems. Trying a MAX3232 instead.

Thinking it was ACIA problem before this, I changed address decoding looking for a bus timing issue. Patching the RX,TX lines together to test the MAX-3232 I noticed I miss wired the ACIA
new chip select. After the loop back test worked with no 6850, I put the 6850 back in after fixing the
wireing and ran the echo test program. That now works and I have 90% working system.
I just need to write the bootstrap loader and set the final memory decoding, before I have working 24 bit system. ( Knock on wood)

1 Like