< I'm surprised by this. I'd thought about ways of linking any number < of old PCs at up to 2000 foot distances, and thought about recreating a 2000ft is within the capability of RS422 at data rates that are in the megabit range. There are other simple solutions like RS423 at low data rates. The DEC mill used to have many central systems that often were remote from the users by as many as 6 floors vertically and several hundred feet horizontally. (Royalt was ML11/M1 and our group was ML3-6/A1) we still ran 4800 or 9600 serial over the 500+ feet of wire of the standard dual twisted pairs of phone co wire. The biggest problem was the possibility of ground loops. With care that's can be avoided though RS422 (balanced differential) can deal with that as can RS485. Allison