Years ago I got ahold of one of these old BetaBrite signs from a business that closed and left behind a bunch of junk. The hand-held remote control was not included, and I had no access to the official PC software, so I had to implement the serial programming protocol myself. I did find some existing implementations in C and Visual Basic, but I was totally unsatisfied with their quality, so I wrote yet another one, in Python.
Thankfully the protocol documentation is very complete and detailed. The sign does have some idiosyncrasies, at least mine does, but it’s not too bad.