I made a simple RS232 cable to connect my PenPad to a modern PC, via a cheapie RS232-to-USB converter off eBay.

Amstrad helpfully supply a diagram of the PenPad's six-pin serial port (which thankfully uses standard RS232 - none of your fancy Psion 3 soap-on-a-rope cables here!) at the back of the instruction manual for the device. Even better - the pin spacing (pitch) is bog-standard 2.54mm or 1 inch if you haven't gone metric. If you don't have a copy of the instruction manual, the pin-out is as follows.

Holding the PenPad normally with the screen facing you, LEFT to RIGHT the six pins are:

1 5V DC (do not connect) -- 2 TX -- 3 RTS -- 4 RX -- 5 CTS --  6 GND [plus two cut-off pins]

Using this information, it was easy to construct a cable using a nine-pin RS232 breakout board, five male-to-female jumper wires and a short length of female pin headers which mate nicely with the PenPad's serial pins.

Next, I will cover some freely-available PenPad serial communication software, which you can still run today using a DOS emulator such as DOSBox or Dosemu2.