What Is BSD?
In the 1970s, AT&T needed a lot of specialized, custom-written computer software to run its business. The company was forbidden to compete in the computer industry, so it could not sell this software. Instead, AT&T licensed its software and the related source code to universities for nominal sums. Universities saved money by using this software instead of commercial equivalents with pricey licenses, and university students got access to this nifty technology and could learn how everything worked. In return, AT&T got exposure, some pocket change, and a generation of computer scientists who had cut their teeth on AT&T technology. Everyone got something out of the deal.
The best-known software distributed under this plan was UNIX.
Compared with modern operating systems, the original UNIX had a lot of problems. Thousands of students had access to its source code, however, and hundreds of teachers needed interesting projects for their students. If a program behaved oddly, or the operating system itself had a problem, the people who lived with the system had the tools and the motivation to fix it. Their efforts quickly improved UNIX and created many features we now take for granted. Students added the ability to control running processes, also known as job control. The UNIX S51K filesystem made system administrators wail and gnash their teeth, so they replaced it with the Fast File System (FFS), which introduced a whole host of features that have crept into every modern filesystem. Over the years, many small, useful programs were added to UNIX, and entire subsystems were replaced.
The Computer Science Research Group (CSRG) at the University of California, Berkeley, acted as a central clearinghouse for UNIX code improvements from 1979 to 1994. The group collected changes from other universities, evaluated them, packaged them, and distributed the compilation for free to anyone with a valid AT&T UNIX license. The CSRG also contracted with the Defense Advanced Research Projects Agency (DARPA) to implement various features in UNIX, such as TCP/IP. The resulting software collection came to be known as the Berkeley Software Distribution, or BSD. Users took the CSRG’s software, improved it further, and fed their improvements back into the CSRG. Today, we consider this a fairly standard way to run an open source project, but in 1979, it was revolutionary.
Fifteen years of work is a lifetime in software development. For comparison, Microsoft went from Windows 95 to Windows 7 in 15 years. The CSRG members collected so many enhancements and improvements to UNIX that they replaced almost all of the original UNIX with code created by the CSRG and its contributors. You had to look hard to find any original AT&T code.
Eventually, the CSRG’s funding ebbed, and it became clear that the BSD project would end. After some political wrangling within the University of California, in 1992, the BSD code was released to the general public under what became known as the BSD license.
The BSD License
BSD code is available for anyone to use under what is probably the most permissive license in the history of software development. The license can be summarized as follows:
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Don’t claim you wrote this.
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Don’t blame us if it breaks.
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Don’t use our name to promote your product.
Taken as a whole, this means that you can do almost anything you want with BSD code. (The original BSD license did require that users be notified if a software product included BSD-licensed code, but that requirement was later dropped.) You don’t even need to share any changes with the original authors! People could take BSD and include it in proprietary, open source, or free products.
Instead of a restrictive copyright, or the more permissive but still restricted copyleft, the BSD license is sometimes referred to as copycenter, as in “take this down to the copy center and run off a few for yourself.” Not surprisingly, companies such as Sun Microsystems jumped right on BSD. It was free, it worked, and plenty of new graduates had experience with the technology. One company, BSDi, was formed specifically to take advantage of BSD Unix.
AT&T vs. the World
Back in AT&T-land, UNIX development continued. AT&T took parts of the BSD Unix distribution and integrated them with official UNIX, and then relicensed the results back to the universities that provided those improvements. This worked well for everyone until the US government broke up AT&T, and the resulting companies were permitted to compete in the computer software business.
AT&T had one particularly valuable software property: a high-end operating system that had been extensively debugged by thousands of people and had powerful features, such as a variety of small but mighty commands, a modern filesystem, job control, and TCP/IP. AT&T started a subsidiary, Unix Systems Laboratories (USL), which happily started selling UNIX to enterprises and charging very high fees for it, all the while maintaining the university relationship that had given it such an advanced operating system in the first place.
The University of California, Berkeley’s public release of the BSD code met with great displeasure from USL. Almost immediately, USL sued the university and the software companies that had taken advantage of BSD. The University of California claimed that the CSRG had compiled BSD from thousands of third-party contributors unrelated to AT&T, and that it was the CSRG’s intellectual property to dispose of as it saw fit. Oddly enough, the lawsuit promoted BSD to thousands of people who never would have heard of it otherwise, spawning open source BSD variants such as 386BSD, FreeBSD, and NetBSD.
In 1994, after two years of legal wrangling, the University of California lawyers proved that the majority of AT&T UNIX was actually taken from BSD, rather than the other way around. To add insult to injury, AT&T had violated the BSD license by stripping the CSRG copyright from the files it had appropriated
Only about a half-dozen files remained as the source of contention. Bruised and broken in court, USL donated some of those files to BSD while retaining others as proprietary information. BSD 4.4-Lite was released, containing everything except the proprietary files. Due to those missing files, BSD 4.4-Lite was the only formal operating system release ever that was known to not be usable or even compilable as delivered. Everyone knew this, and bought it anyway—a historic feat that modern vendors probably wish they could replicate.
A subsequent update, BSD 4.4-Lite2, is the grandfather of OpenBSD, as well as all other BSD code in use today, such as that in FreeBSD, NetBSD, and Mac OS X.