I will look through some of my stuff for an old copy of HP-Basic a.k.a. Rocky Mountain Basic. I understand exactly what you are looking for, and know why the other software packages will NOT work. Unforturnately, as you have already found, HP-Basic is virtually extinct, and heavan forbid, you finally get a copy of the program, and a harddisk goes out! (Have you tried to find one of those yet? GOOD LUCK!!!) You might have to bite the bullet and upgrade. I know that you will be starting from scratch, and all of your setup will have to be redone (unless some of these new programming languages can handle GPIO communication????), but for the sake of your sanity and wallet, you might just want to upgrade.
Will let you know if I find it! Good luck and keep us posted.