You know what's funny is that I remember playing Ghostbusters at a friend's house on his C64, too!
Did you know that the Ghostbusters game you're referring to was made by David Crane, the same guy who made Pitfall and A Boy and His Blob? I've met David Crane in person twice! Once at E3 and once at the National Videogame Museum. Unfortunately, Ghostbusters isn't one of David Crane's better games.