On 3/13/2017 1:00 PM, cctech-request at classiccmp.org wrote: (I've also engaged your question on the ADTPro support forum... that's probably a better place to debug this. But for the group...) Assuming there isn't a hardware issue like the null modem being plugged into the wrong DIN5 socket on the IIc, my guess is there's a bit-width issue with Java. First, some background: it sounds like you've been hacking around with (the location of) the RXTX serial library, which should not at all be necessary; it should be left where it is after unzipping the ADTPro distribution. Also, it's unusual for Windows not to recognize the FTDI-based chip in your UGREEN adapter; it should be automatically downloaded and installed. You should not need to install it manually. You should see the COM port populate in the Windows hardware manager when you plug it in (and the device driver is correctly installed). You said your Windows was version 7, 64-bit. Let's check Java. Go to a command line, and run 'java -version'. The build identifier will let us know if it's 32- or 64-bit. If it doesn't match your OS, that's the reason why ADTPro can't see the serial port (through RXTX). - David