Back in the 70's or 80's I used to watch PBS late night and they'd have Doctor Who and other Sci Fi series on.
There was a series the I've been trying to find with a large 'generation' ship. As I recall the ship had apparently crashed into the planet so that one end was like prehistoric cavemen and the other end was highly advanced. The main cast travelled from one end of the ship to the other during the series. I don't think it was Starlost because I remember scenes where it showed the ship attached to the planet yet out into space as well.
Anyone remember this?