An older guide to getting a Psion 3a communicating with a Mac; Very outdated, but will probably still work.
I'd use this approach instead.
Download Ubuntu Server:
In this example, I’ve used the current LTS release, which is 14.04.3 LTS.
Also, download VirtualBox:
Create a new VM like so:
Run the following:
sudo apt-get update && sudo apt-get upgrade && sudo halt reboot sudo apt-get install plptools
Now time to test the connection. Plug the cable into the Psion and the USB port on your Mac.
Switch on link mode on the Psion at 9600 bauds and type this:
sudo ncpd --verbose=all --serial=/dev/ttyUSB0 --baudrate=9600
If the service started successfully, you should see it listed here:
ps -ef | grep ncpd | grep -v grep
Now initiate the FTP connection to your Psion:
If you see the
> prompt, try typing
dir c:, and you should see the contents of your main drive. If this work, congratulations! You’ve successfully formed an FTP connection to your psion.
When you’re done testing, type
bye to exit the FTP session, and then at the bash prompt
sudo pkill ncpd to terminate the connection with your Psion.
Now we can proceed to connect the VM to your Mac, and create a complete interface between your Mac and your Psion.
At the moment, your VM won’t know how to identify itself on the network by name (we’ll get to that in a bit), so you’ll need to ssh to the ip address:
ifconfig ssh <username>@XXX.XXX.XXX.XXX sudo apt-get install plptools ncpd