Back in the pre-internet days (at least before the internet was commonly available in the home) you could use what was called a null-modem cable to connect two computers, to play games for example (Falcon was one such game). Simplistically, a null-modem cable was a serial cable that crossed it's transmit and receive lines on each end of the cable. Here is a
diagram.
Me and a friend who shared a common bathroom between our rooms in a dormitory built one of these cables one time, strung it between our rooms, and would dogfight against each other in Falcon on our Amigas. Crashed quite a bit if I remember correctly, but this was around 1992 and kind of a novelty at the time, we had
alot of fun with it.
As for Unimodem, I think it was a brand of modem.
[This message has been edited by Jason Menard (edited December 19, 2001).]