Bob Kahn: The contract was awarded in I want to say January of 1969, and it was kind of a nine month delivery cycle for the first node on the net. We called it an Interface Message Processors, or IMPs. These were really packet switches built out of mini-computers. We used Honeywell 516s.

Bob Cringely: Yeah. The size of a phone booth.

Bob Kahn: Yeah, or a refrigerator really. And heavy as can be, but they worked. They worked out the box, so to speak.

And nine months we had the first one, ten months we had the second one, eleven months the third one. So by December of 1969 we had a little four-node network deployed on the West Coast. One at UCLA, one at Stanford Research Institute up in Menlo Park, one at the University of California at Santa Barbara. That was the third one. The fourth one was at the University of Utah. So a triangle in California and a little spur out to Utah, and based on how well that worked DARPA was reserving the right to put more nodes on the net, and of course it worked so well that they immediately went into the second phase and that turned it from a 4-node net into a 19-node net and then eventually it became over 100 nodes until it was finally split into pieces in 1983.

We had to deal with the issue of unreliability along the way, and we had to deal with the issues of addressability, and those were two of the main issues that led to the re-conceptualization of the protocols and we called it TCP at the time and later we took the part of it that dealt with the Internet protocol and sort of broke it out and made a separate thing. That's where the name TCP/IP came from. So the IP part had to do with addressing the machines and having the networks route based on IP addresses, and the TCP part was sort of the end-to-end piece of the protocol that lets you put the things back together again.