The Dream Machine by M. Mitchell Waldrop

Author:M. Mitchell Waldrop [Waldrop, M. Mitchell]
Language: eng
Format: epub
ISBN: 9781732265110
Google: Hl2pugEACAAJ
Publisher: Stripe Press
Published: 2018-09-25T23:33:39.644929+00:00

Over the next six months, with input from Len Kleinrock, Dave Evans, and a number of other enthusiasts, Roberts crafted a preliminary network plan containing specifications for the response time, the reliability criteria, the number of bits in each packet and their layout, the transmission speed in bits per second—all the engineering nitty-gritty. He then gave the initial plan its debut presentation in October 1967, at the ACM Symposium on Operating System Principles in Gatlinburg, Tennessee. And as he sat down afterward, he had reason to feel satisfied: this was something genuinely new in the world, a way to organize communications that was radically different from anything that had gone before.

Except that shortly thereafter, an Englishman named Roger Scantlebury got up to give a paper on a system being developed by Donald Davies’s telecommunications research group at the National Physical Laboratory (NPL) in Teddington, outside London—and proceeded to describe essentially the same idea: packets, IMPs, distributed control, the works.

What the ...?

The story, as Scantlebury would explain it to the disconcerted Roberts later that day, was both ironic and sad. The irony was that Donald Davies had gotten his original inspiration when he was hosting a conference on time-sharing back in late 1965 and fell into an impromptu discussion about networking with J. C. R. Licklider and Roberts himself. Almost immediately after that, Davies had been struck by the notion that a store-and-forward system with very short message segments would be perfect. By June 1966 he had expanded this idea into a formal proposal, calling for a United Kingdom—wide digital network running at speeds of up to 1.5 megabits per second. This paper was where he introduced the concept of an “interface computer,” the equivalent of Wes Clark’s IMP, and coined the term “packet” to describe the message segments (at that point Roberts and his ARPA colleagues were still calling the segments blocks). Davies’s name for the scheme as a whole was “packet switching.”

From there, said Scantlebury, Davies and his group at Teddington had continued to develop the packet-switching idea with computer simulations. They had even scraped together enough money to build a “one-node” network, consisting of a single Honeywell computer connected to a lot of terminals through a special interface. It wasn’t much, admittedly. But it did demonstrate the switching principle: you could type in text on one terminal and have it print out on any other terminal you specified.

And that, explained Scantlebury, was the sad part of the story: the powers-that-be at the British Postal Service, which had absolute control over the U.K. telecommunications system, had flatly refused to fund Davies’s vision of nationwide packet switching. They couldn’t even see the point of a demonstration. So, said Scantlebury, having gotten there first, the NPL group would now have to sit back and watch as the Americans did a packet-switched network for real.

That hurt—and Roberts could certainly sympathize. Still, the frustrations weren’t personal. Scantlebury and his companions from the NPL group were happy to sit up with Roberts all that night, sharing technical details and arguing over the finer points.

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