This November, the Unix community has another notable anniversary to celebrate: the 40th birthday of the first edition of Ken Thompson and Dennis Ritchie's Unix Programmers Manual, released in November 1971. Producing the document was no easy task, because at that point the Unix operating system grew by the week; budding aficionados added new commands and features to the system on a regular basis.
"The rate of change of the system is so great that a dismayingly large number of early sections [of the text] had to be modified while the rest were being written," Thompson and Ritchie noted in their introduction. "The unbounded effort required to stay up-to-date is best indicated by the fact that several of the programs described were written specifically to aid in preparation of this manual!"
That's why Unix timelines are fun to read—they give a sense of how quickly the system collaboratively evolved. But some of them either skip or mention without explanation a government decision that, in retrospect, paved the way not only for Unix, but perhaps for the open source movement as well: the 1956 Consent Decree between the United States Department of Justice and AT&T.
That crucial decision didn't exactly force AT&T to share Unix with the world, but it made the decision much easier.
Dangerous program!
The Unix operating system was born during the most creative point in any technology story: failure. One day in 1969, an administrator showed up with bad news at the fifth floor of AT&T's Bell Telephone Laboratories (BTL) in Murray Hill, New Jersey. Bell was shutting down The Multics Project, he explained. (Multics was BTL's first attempt to create a time-sharing system that would allow many users to access and work on a computing network simultaneously.)
For the project staff, the news came as a blow. This was a "traumatic change... The toy was gone... there was a clear lack of momentum," one staffer recalled. But the cold truth was that Multics did not work.
"Multics couldn't even accommodate three users efficiently," writes Unix historian Peter Salus in his engaging book A Quarter Century of Unix. "Computer research at BTL was in the doldrums."
Undaunted, BTL programmers Thompson, Ritchie, and others informally soldiered on with a smaller-scale version of the concept on a PDP-7 minicomputer. The standard version of Unix history notes that Ken Thompson ran his Space Travel game program on Multics and wanted to keep it around. The new project, however, was about a lot more than that. By telling the suits upstairs that they were developing text editing software, the group even managed to wheedle a superior PDP-11/20 machine from Bell.
"Rather than irritating the great judicial dragon," AT&T's legal department decided to license Unix patents too.
"We knew there was a scam going on—we'd promised a word processing system, not an operating system," Ritchie later admitted. The team did deliver Unix as a text processing application to the Patent Department, but an operating system was what Bell eventually got—albeit a rough one at first.
"Program development generally occurred out-of-hours," a programmer subsequently explained to Salus. "The terminals on the development machine were in a common room and when several people were at work, one would call out 'dangerous program!' before executing a new a.out file (the default output file from the linking editor). This allowed others to save their editor-files quickly (and often)."
By the early 1970s, the basic components and concepts associated with Unix were established. Written in the C programming language, Unix offered a tight array of efficient "tools" or applications, whose text streams could be "piped" from one program to another.
"Unix now had a language all its own," Salus notes. "It had a philosophy, an ethos. It had a relatively small group of devoted users on a handful of AT&T Bell sites." The question now was what AT&T would do with the new OS.
Ready to do our part
Almost twenty-five years before the first Unix Programmers Manual was released, the United States Department of Justice announced that it was pursuing an antitrust action against AT&T, which controlled most of the nation's telephone network. The 73-page complaint was released in 1949, just after Harry Truman was reelected to the White House. It charged AT&T with running a price-fixing conspiracy. The document also accused AT&T subsidiary Western Electric of monopolizing the market for telephones.
The DoJ demanded that AT&T be divested of the device-making company, but the Korean War exploded a year later. AT&T responded by wrapping itself in the American flag, noting its role as a defense contractor and its management of Sandia Labs.
"The Bell System has always stood ready to do its part in the national defense by undertaking work for which it is particularly fitted," AT&T's president wrote to David Lilienthal, Chair of the Atomic Energy Commission. But, he added, "this situation in relation to the antitrust suit made us question with you whether it would in fact be desirable in the national interest for us to undertake this project."
By 1951, AT&T had the Pentagon on its side. "It is clear to me that the mobilization effort will be impeded by pressing this suit," warned the Secretary of Defense that year. He asked that the DoJ action be postponed "while the present situation continues to exist."
A year later Truman was gone, replaced by Dwight Eisenhower. AT&T pressed Eisenhower to dismiss the antitrust suit. In the summer of 1953, the administration's new Attorney General Herbert Brownell met with the telco's General Counsel T.B. Price.
At the meeting, Brownell asked AT&T to think over a voluntary settlement. "He asked me whether, if we reviewed our practices, we would be able to find things we are doing which were once considered entirely legal, but might now be in violation of the antitrust laws or questionable in that respect," the AT&T representative later recalled. The new attorney general also assured AT&T that "if a settlement was worked out he could get the President's approval in 5 minutes."
Such a list of things was submitted, and in 1956 AT&T and the government entered into what was called the "Consent Decree" on the matter.
Keeping the beast quiet
Central to the consent decree was a provision that Bell Systems patents be licensed to competitors on request. AT&T had 8,600 patents cross-licensed to General Electric, RCA, and Westinghouse. These were now to be licensed without royalty payments to applicants other than the aforementioned companies, and future AT&T patents had to be licensed to applicants at "reasonable royalty" rates, and necessary technical information had to be shared.
Equally important was a requirement that AT&T stay out of "any business other than the furnishing of common carrier communications services." The decree also enjoined Western from "any business not of a character or type engaged in by Western or its subsidiaries for Companies of the Bell System."
As telecommunications historian Gerald Brock notes, this deal didn't interrupt the big picture. It allowed AT&T to keep Western Electric and its monopoly, but it made the telecom much more dependent on regulatory decisions. AT&T "lost the freedom to enter other markets when it saw that advantage," Brock observes.
The agreement also made AT&T much more circumspect about innovations coming out of Bell Labs. "The lawyers at BTL were conservative," Salus explains. "There was no sense in aggravating the beast that was the Justice Department. No business but phones and telegrams."
Pay in advance
It was in this context that Ken Thompson presented his work to the Fourth Association for Computing Machinery Symposium on Operating Systems Principles in October of 1973. Suddenly "a trickle of requests" for more information started coming in from sites "that had nothing at all to do with BTL, AT&T, or Western Electric," Salus writes. The publication of the paper "started a flood," especially from universities looking for affordable software.
AT&T's response to this windfall was caution. "The company took a very self-constricting view of the decree," one Bell programmer later explained, and so worried about Unix. In fact, AT&T management "didn't understand what we had in Unix," another administrator later conceded.
Thus, "rather than irritating the great judicial dragon," AT&T's legal department decided to license Unix patents too, "but would make it clear that it had no intention of pursing software as a business." A retrospective talk about AT&T/Unix marketing policy given ten years later described the Bell Unix terms:
- No advertising
- No support
- No bug fixes
- Payment in advance
This did not daunt university and government systems operators. The Patent Licensing office at Bell in 1970 usually negotiated four or five deals a year. By 1974 "the office staff were, simply, overwhelmed by the number of requests for Unix licenses," Salus explains. It only got worse "when the first military and then commercial enterprises asked for licenses."
Did AT&T's refusal to provide technical support hurt Unix? Quite the opposite, argues Salus. Instead, the policy had an "immediate effect: it forced the users to share with one another. They shared ideas, information, programs, bug fixes, and hardware fixes."
Unix was a "godsend" for university computer divisions, observes computer historian Paul Ceruzzi. For a nominal license fee they could obtain the source code, run it through a C compiler, and farm debugging and development out to cheap graduate student labor. "By contrast, most computer vendors guarded source code as their family jewels, seldom gave it out, and did all they could to lock a customer into their products."
In other words, AT&T's Unix policies helped Unix become the operating system that we've all come to know, and, if not love, understand as empowered by a philosophy that also informs the "open source" movement of our time.
Not everyone agrees with this interpretation. Timelines and histories about open source rarely or only briefly mention the Consent Decree or its impact on AT&T and Unix. "In the 1970s AT&T distributed early versions of UNIX at no cost to government and academic researchers," Wikipedia notes, "but these versions did not come with permission to redistribute or to distribute modified versions, and were thus not free software in the modern meaning of the phrase."
It's hard to imagine, however, that the early Unix experience didn't help create expectations that paved the way for open source. In any event, the 1956 Consent Decree probably doesn't get too many birthday notices on Facebook. For the record, this year it turns 55.
Further reading
- Peter H. Salus, A Quarter Century of UNIX
- Gerald W. Brock, The Telecommunications Industry
- Paul E. Cerruzi, A History of Modern Computing
Listing image by Photograph by PanelSwitchman
reader comments
58