T171 - TMA04
Name: Lois Ann Morris PI: T8318286 Date: 31st August 2001.
"UNIX and its influence on the Internet."
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Introduction................The beginnings of UNIX. Section 1....................UNIX and TCP/IP. Section 2....................UNIX and the Open Source Software movement. Section 3....................UNIX and Usenet. Conclusions................Conclusions - the significance of UNIX. Additional information References..................sources of information I used to write this report A UNIX Chronology (46.4kb)
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The beginnings of UNIX.
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UNIX is an operating system designed in the early 1970s by programmers Ken Thompson and Dennis Ritchie at Bell Laboratories, the central research and development facility of AT&T . Originally designed as a programming environment for developing software, at its heart is the kernel providing the most basic functions of the operating system accompanied by a set of software tools for carrying out specific tasks. The kernel comprised just 11,000 lines of assembly language, very hardware specific and not far removed from the machine code used by the processor for its operations.
Soon UNIX became very popular in computer science departments since lecturers and their students could use it, take it apart, study it and alter it. Not only did this have benefits for the development of computer science as a whole, it also opened up UNIX to a huge number of programmers who wrote improvements to the operating system and carried forward its development in a wide collaborative effort. Having been written for programmers, UNIX was powerful and flexible and variants were developed, often tailored for specific tasks.
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In 1974, Dennis Ritchie rewrote 10,000 lines of the assembly code in a new higher
level language called C which made UNIX much simpler to adapt to different computer systems. Unable to sell UNIX due to the Consent Decree of 1956 which restricted its business to the national telephone system, AT&T responded to the interest in UNIX by effectively giving it away to academic institutions. It also made a critical decision to include the source code (the kernel written in assembly and the rest of the operating system written in C) together with a licence which allowed licensees the right to alter the source code and share the alterations with others.UNIX and TCP/IP.
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Vint Cerf and Robert Kahn’s paper, “A Protocol for Packet Network Intercommunication”
published in May 1974, outlined TCP or Transmission-Control Protocol, establishing the principle of messages being broken up into ‘datagrams’ then transmitted as packets across the network. By 1982, TCP/IP, as an 'open standard', became the dominant protocol of the growing network. With its various research departments using a variety of mainframe computers, the US Department of Defence took the decision to standardise the operating system, choosing UNIX specifically because it was portable to many different systems. The TCP/IP protocols were included as military standards - a requirement for many research contracts. One of the various incarnations of UNIX was BSD (Berkeley Software Distribution) produced at UC Berkeley in California. It achieved widespread use in research and academic establishments. In 1984, version 4.2BSD, including a complete implementation of the TCP/IP networking protocols, was released under the AT&T Open Source style software license. 4.2BSD was very popular and accelerated the spread of TCP/IP, especially as more and more sites were connected to the growing ARPANET. Also, UNIX was being ported to a growing number of different types of computer hardware and the combination of Ethernet networking with TCP/IP allowed many different types of systems to share and use data. In 1984, after the annulment of the Consent Degree, the Open Source software licence was withdrawn from UNIX and the cost quickly became prohibitive for many users. Since the TCP/IP networking code had been written at Berkeley, the decision was taken by UCB to split it from the main BSD version and make it available as Networking Release 1. This was the first freely redistributable code from Berkeley and had extremely relaxed licensing terms. Basically, the code could be released in any form as long as the UCB copyright notice was included intact and use of its code was acknowledged. It was followed by the updated Networking Release 2 in June 1991 which was also free for download.
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Due to a bitter two year lawsuit, started in 1992, in which AT&T alleged that UCB had used now proprietary UNIX code in its BSD distribution of UNIX, Bill Jolitz constructed 386/BSD, a full Open Source UNIX clone specifically for 386 based computer architecture. This was released just six months after Networking Release 2 and became the basis for three Open Source UNIX distributions - FreeBSD, OpenBSD and NetBSD.
UNIX and the Open Source Software movement.
The GNU Manifesto, published by Stallman in 1985, was one of the first formal documents of the Open Source revolution. He also devised the GNU General Public License which allows free distribution of software and requires that the source code together with any code improvements be provided. Stallman is at the heart of the open source versus proprietary software debate currently raging in the computing community. As Microsoft tightens its grip, he and others are campaigning for the right to use software freely without copyright and intellectual property caveats. That Microsoft takes the OSS threat seriously is indicated by the infamous Halloween Documents first brought to light by Eric Raymond. Microsoft was obliged to acknowledge the authenticity of the documents
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A widespread use of UNIX and Linux on the Internet has been to run the powerful Open Source web server called
UNIX and Usenet.
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computer science communities. Programmers from all these communities contributed improved code or new programs and utilities. Inevitably UNIX had bugs which had to be fixed and code
improvements which had to be logged. All of these had to be incorporated into new releases and
updated version of UNIX which proved to be quite a logistical headache for AT&T. In 1977, a Bell Labs researcher, Mike Lesk, developed an automated maintenance system which included a program called UUCP (UNIX-to-UNIX Copy) which enabled one computer to call another computer using a telephone line or Ethernet network and deliver software directly. In this way, software could be updated and tested remotely, easing the distribution of new releases and updated versions of UNIX. An improved version of UUCP was incorporated into V7 UNIX and distributed in 1979 to the academic communities. This was seized on by three students at two different universities in North Carolina who had the idea of using UUCP on their UNIX computers to exchange updates to specified files across the telephone network. They wrote a program called NetNews to automate this, written in the command language of UNIX. NetNews was very slow and resource-hungry so the program was rewritten in the ‘C’ language, making it much quicker and more efficient. This was News version ‘A’ which was first described as ‘Usenet News’ at the UNIX Users Association conference in January 1980. The only requirement for entry into Usenet was a computer running UNIX and access to a telephone line. In 1986, a new package was released using the Network News Transfer Protocol (NNTP) which allowed hosts to exchange articles using 'open standard' TCP/IP connections instead of UUCP. The NNTP protocol, developed at UCBerkeley, was released as an integral part of 4.3BSD. Usenet and ARPANET were unofficially joined in 1981 when they intersected at UCB Berkeley and ARPANET discussion groups were made available on the Usenet network, broadening the scope of the ‘Poor Man’s ARPANET’. Arrangements were made which allowed Usenet to ride on the ARPA network and, later, on the Internet. |
Conclusions - the significance of UNIX.
In conclusion, it is clear that UNIX has had a very great impact on the Internet. Also, like many other brilliant concepts in the world of computing, it appears to have been very much a chance happening. Thompson and Ritchie were dissatisfied with the software tools they were given to work with and, like so many programmers, simply decided to create their own. From there, UNIX gained momentum as it spread, first through AT&T, and then out into the wider academic and research spheres, where its simplicity and portability soon made it the dominant operating system. Powerful, flexible and cryptic, it is not easy to learn having been created by programmers for use in software development. The integration of the 'open standard' TCP/IP protocols into Berkeley’s UNIX distribution meant that this vital code was quickly disseminated into all the other UNIX variants and gave the ARPANET a considerable boost. First UUCP and then the combination of NNTP and TCP/IP allowed the birth of Usenet and eventually led to the Internet taking over from the ARPANET.
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