Resurrection of the 1973 IMP code

[updated 2020-06-12]

Story of the 1973 IMP listing.

A few years ago Paul Wexelblatt was getting rid of stuff and came across a bunch of BBN documents and software listings. Dave Walden picked them up from Paul, as at that time Dave was working on a history of computing at BBN, with a promise to pass on to Bernie Cosell whichever of the documents Bernie wanted. Among these documents was a 1973 assembly code line-printer listing of the ARPANET IMP software system, the only remaining early IMP system listing of which we know. Bernie, Dave, and Tony Michel dreamed of somehow obtaining a text version of this listing which could again be assembled into machine code for the modified DDP-516 computer on which the IMP system was based. A couple of attempts to scan the system were made before a decent, albeit only 300 ppi, scan was made. Attempts to OCR the scan into text, however, were initially unsuccessful, and we merely posted the scans on the web. Then in 2013 a set of people in Silicon Valley got involved (introduced to the BBN people by Jack Haverty). Charlie Neuhauser, James Markevitch. and Bob Armstrong suppored successful scanning of the listing, OCRing of the scan, assembly of the program from the listing, and emulation of the assembled code on a 316 IMP emulator. Thus, the 1973 IMP code was run again in a network of emulated instances of IMP hardware.

Participants in the IMP software evolution, 2013 software resurrection, and writing the paper for the IEEE Annals of the History of Computing

Among the people who were involved with the packet switch code or this recounting of its history were Len Abram, Peter Allen, Ellie Baker, Ben Barker, Helen Bowns, Rosemary Carter, Eugene Chang, Steve Cohn, Bernie Cosell, Will Crowther, Peter Cudhea, Jim Dempsey, Eric Elsam, Miles Fidelman, Walter Gillett, Jack Haverty, Jim Herman, Bob Hess, Alan Hill, Bob Hinden, Doug Hirsch, Morris Keesan, Richard Koolish, Mike Kraley, Ken Laube, Joel Levin, Ben Littauer, Andy Malis, Alex McKenzie, John McQuillan, Tony Michel, Tom Peters, Ken Pogran, Drew Powles, Peg Primark, Ira Richer, Eric Roberts, John Robinson, Cliff Romash, Eric Rosen, Paul Santos, Linda Seamonson, Ken Turkewitz, Dave Walden, Jil Westcott, and Paul Wexelblat.

In addition to some of the people listed in the prior paragraph, the people involved in the 2013 recovery of the IMP code were: Bob Armstrong, Tom Kilbourn, James Markevitch, and Charlie Neuhauser, who reside and work in Silicon Valley, and BBN librarian Jennie Connolly.

Tell me if you think you should be in this list. -Dave

Network list

On October 4 and 7, 2013, an exchange of emails on the ex-BBN mailing list listed some of the companies to which BBNCC and other parts of BBN delivered networks — among them ARPANET/MILNET Abbey Bank, Amadeus, BBN Networks, BBN net, Bank of Hawaii, Barclays, Berkeley Library, Burlington Northern, Chembank, Citibank, Customs/Treasury, DISNET 1,2, 3, ENI, 5th Signal Net, ISTEL, ITT, IRRC, Irving Trust, JAL, KDD, MCI, MINET, Many military exercise networks (Reforger, Forger, etc.), Marriot, Mastercard, Michigan Bell, NKK, NatWest, Nexis, On-Line Systems, PGI, Packet Radio Net, Packet Voice Satcom, Schulumberger, Sixtel, USAF Academy, VISA, Wang, Weyerhauser, WINNET, Wideband net, and several classified networks.

Contributors to this exchange were Jack Haverty, Bernie Cosell, Ken Turkewitz, Ben Barker, Morris Keesan, Cliff Romash, and, with particular good memories or personal archives, Alan Hill and Peg Primak.