Arpanet Reconstruction Project

Surf the Arpanet like it's 1972 again

This is the entry page for a faithful recreation of the Arpanet circa 1972-73, connecting replicas of the historical computers, running their recovered historical software, and talking to each other again over replica IMP routers - also running their original firmware. Explore the Arpanet and details of its nodes through the interactive chart below. Or read on to get a live terminal into the early 70s.

This is work in progress! We hope to recover and reconstruct more and more Arpanet nodes over the coming months and years. Which is why, for now, this page is not public yet. Please bear with us - or even better: contribute.

The Arpanet

The ARPANET was built as a network of Interface Message Processors (IMPs), the world's first routers. Actually, they were rugged mini-computers that handled all packet switching and routing. Host computers (the mainframes and minicomputers at universities and research labs) connected to an IMP, which handled all network communication for them. Later, Terminal Interface Processors (TIPs) were added, modified IMPs that could connect to ordinary text terminals, not just full computers. They allowed access to the ARPANET without the need for an actual host computer on site.

Interactive map of the 1973 Arpanet

Hover over the nodes for details and their detailed subpages.

Colored nodes are ones that played a role in the Scenarios for the 1972 Arpanet Ball described below.

Green nodes are currently accessible in the reconstruction;
yellow ones are expected soon;
red ones will take longer to reconstruct.

The 1972 Arpanet Ball

The Arpanet. At first, not many people cared. The break-through came at the 1972 ICCC convention, known as the 'Arpanet Ball'. Attendees could get online, and were given a booklet with 'scenarios' to try for themselves.
No exaggeration - at the Arpanet Ball, the consequences of 'internetworking' suddenly became clear. Before, only a few insiders realized. After, it was widely understood that this would change the world. That helped the Arpanet grow explosively in its early years. Click below for an animation, or read more: here, and here.

See the Arpanet expand from 1969 to 1976

It is not completely fair - not at all fair - to attribute the explosive growth in 1973 to just the Arpanet Ball, which happened in October 1972. But the Arpanet's node count explosion in 1973 was accompanied by a wave of broad enthusiasm about internetworking. And that most definitely did start at the Ball.

Growth in the number of nodes flattened off after 1975. After six years of development, the network was no longer best suited to management by an agency with the charter to sponsor advanced research, and thus network management was transferred to the Defense Communications Agency.

So, it is interesting (actually, historically important!) to find out what exactly people saw at the event. Here is the invitation letter. Promising that the program will 'stress the user':

Attendees must have experienced more than just stress - what triggered them to see the internetworked future? It certainly was not websites, they only came in 1989. In late 1972, even email was less than 12 months old, and interestingly: that's not even one of the example Scenarios attendees could try out. Instead, people were shown how to mail each other on MIT's ITS systems locally!

But, attendees could log themselves in on clunky Teletypes or very basic CRT terminals; they then could connect to the various computers on Arpanet and 'do things'. What things? That is why we recreated the Arpanet circa 1972-1973, and let you go through the example 'Scenarios' yourself.

The Scenarios

At the 1972 convention, a booklet was given to attendees. It contained step-by-step instructions to try interesting things on the Arpanet. Each 'Scenario' gave a short tour through one of the nodes that joined in on the effort.

Try it. Log in on an Arpanet Terminal and teleport back to 1972

Pretend you are an attendee at the 1972 ICCC convention. There were dozens of terminals, so pull up a chair and pick one of the free (green) terminals below. Take your pick: a clunky Teletype, rattling along (we include the audio, and mercifully, a mute button) as it prints its output on virtual paper, or one of the new, fancy DEC VT05 terminals. To which you still had to get used in 1972, just so you know.

Bring your own IMP: Become part of the network

We added extra 'leased line' sockets on a soe Arpanet IMPs. These let you hook up your own, local, IMP replica to become part of the network. Not too hard, and then attach your PiDP-10 or even PiDP-11/8/1 replica to your IMP. Or a Linux machine - if like the MIT ITS team, you do not believe in security.

Thanks to the self-organizing technology of the Arpanet IMPs, it only takes half a minute for your IMP's presence to be propagated through the network. And cut the cables whenever you want, no problem.

Connect your IMP & PiDP replicas

Use your own (replica) Terminal

We have an array of excellent terminal simulators that will bring you on the Arpanet in a much more stylish and comfortable manner.

In fact, you can hook up a real serial terminal, if you have one.

Some of the terminal emulators available: VT-100, VT-52, Datapoint, IMLAC, Tektronix. Or, plug in your Knight TV terminal as if you were a student at MIT's 545 Tech Square. Why stay stuck at the Washington Hilton.

Connect your own terminal