I have a ProNav 100 from the early 80s , later bought out by Garmin as their 100.
Was an excellent command bar tracking device, which also answered all the in flight questions. Certainly ended the stick and pencil and prayer wheel era.
Is there a museum of gps or collectors of this technology, I really hate chucking this old magic stuff in the dump.
re the square protractor, I’ve never seen the height line idea before. Mine had a centre string to pull out along the map to get the track angle. Hi techo !
My first computer was WW2 box with a roller blind. Compare all that with Ozrunways and etc. Incredible.