At that time, was Comcast a relatively small company? I guess it covered only some of the Northeast, such as Philadelphia, Boston, DC, and Baltimore.
I apologize for the bumping of this topic  

 , but I wanted to reply to this previous posting  

Anyway, I would imagine Comcast was smaller back then, but Comcast was founded in 1963, so it has been around for a while. 
Back in the 4000 days, we had at least two cable providers. I know one was AT&T (whose headends were bought out by Comcast in 2001), and I think the other was a company called MediaOne.