I bought the Psion and a number of blank 32K DataPaks. I have no Comms Link so no means to get any data onto the Psion (other than typing it in).
So, the first task was to build a DataPak reader/writer.
Jaap's excellent website https://www.jaapsch.net/psion/ has all the information I needed to build a DataPak reader/writer. Using an adruino pro micro. This uses 8 pins as a data bus, 5 pins for control (RESET, CLOCK, OUTPUT ENABLE, SLOT SELECT and PROGRAM) and one to generate the programming voltage via a boost converter.
With this, I was able to program the CommsLink 4.2 software into a blank DataPak.