Nice work - I just use one of Bob Applegate (rip)'s RS-232 cards. They work great with the KIM and probably other KIM-like devices.

For uploading, I wrote this (plain C). It converts raw binaries to the KIM papertape format transparently and uploads (and executes) in one step, or you can hand it preprocessed papertape text files. https://github.com/classilla/kimup/

This is really cool to see. The documentation on paper tape is a great find.

I fully expect that DavePL will piggyback on this and connect his KIM-1 to his rebuilt PDP-11