My folks used to go to the movies a lot back in the 70s when they were dating and first married and it was alot of scifi films like this. My dad really liked this one and i remember being really little when he showed it to me on tv or even VHS. Sunday afternoons after wrestling they'd have movies on the local channels back in the 80s into the 90s and I remember seeing logan's run for the first time when i was in like first grade so i'm sure i saw this then too. This was sort of the golden age for non blockbuster scifi: Silent running, planet of the apes, soylent green, omega man, logan's run, westworld. So many great movies with simple but effective effects and actors who didn't have the charisma of a broken doorknob.