Recently I had the pleasure of jail-breaking a very old iPad to recover some things off of it. One of the most annoying things I experienced was checkrain's only tool for getting a terminal to PongoOS only having a makefile for MacOS.
This is a python script that follows the same protocol as shown in pongoterm.c
Connect a device running PongoOS on USB and run the script with python.
There is one special command, /send <file>, which will upload a file such as a kph or ramdisk for use.