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Section 4.
Linux history.


"One of the main advantages of Unix over, say, MVS, is the tremendous number of features Unix lacks."

Chris Torek.

4. Linux history.

4.1. A short history of UNIX.

"In the late 1960’s Ken Thompsom joined the computing-science research group at Bell Laboratories, which is the research arm of the giant American corporation ATT. He and many colleagues had been collaborating with MIT and GE on the development of an operating system called Multics which aimed to improve the performance of multi-user time-sharing computer systems. But the resultant system was too big and too slow, so Bell lab’s withdrew leaving the computing science group without a computer.

A cast-off PDP-7 computer became available, so that Thompsom set about rewriting a planetary motion simulation program previously implemented on the GE system. At the same time he experimented with many of the concepts used for Multics, working in PDP-7 assembler he developed a hierarchical filestore, a number of utility programs and central supervisory program (known as the kernel) which together made up a rudimentary single-user operating system. He called it UNIX, a poor pun on uni-MULTICS i.e. single-user MULTICS or was it a pun on eunuch version of MULTICS ?

Thompson’s system found favour with his colleagues in the Bell labs computer science department because it made software development work easier. Some text and processing utilities were added to the system, which were used by the legal department and earned the developers enough funds to obtain a PDP-11 a more reliable and modern system. The 16-bit PDP-11 became the second UNIX port, and enabled multi-user facilities because of the memory management hardware.

One of Thompson’s colleagues was Dennis Ritchie who had been impressed with the BCPL language developed at the University of Cambridge, which he used as a template for a language he designed called B. This language developed into C which begged the question what would the next language be called would it be D ?, or would it be P?. The answer we now know is C++.

The language C was then used to completely rewrite UNIX apart from a few hundred lines of assembler code. This enabled the first port of UNIX onto a non-DEC computer, a 32-bit INTERDATA 8/32 minicomputer system (with a similar architecture to the IBM 370) and highlighted some of the more non-portable aspects of the system

The combination of an environment designed for program development and the use of high-level language to code systems software greatly enhanced the possibility of a single programmer understanding the workings of a multi-user multiprogramming system. Thus UNIX flourished within BELL labs and they made public Version 6 which ran on the PDP-11 range and was licensed to universities without any support, but with all the source code for the media cost. Commercial organisations could obtain UNIX for about 20,000 pounds. Surprisingly some did!. Version 6 was still small enough to appear on micro-processor systems (e.g. Z80, Motorola 6809, Intel 8085 etc...) as well as a variety of mini and main-frame systems. Other companies like Whitesmiths consolidated around V6 (IDRIS) because of its small size made it suitable for smaller real-time control applications, whilst others like Motorola opted for choosing the best ideas (OS9) but not attempting UNIX compatibility.

By Version 7 UNIX had developed and matured into a relatively bug-free product which ran on many different types of processor.
Taken from "A Short History of UNIX" by Liam Madden.

For the full text see
http://www.unix.com/unix-dummies-questions-answers/7-short-history-unix-l-madden-ic-ac-uk.html

4.2. 1991 Freax.

Linux was developed by Linus Torvald when a student at Helsinki University in 1991. Linus was frustrated by the lack of a complete operating system kernel with which he could work while a student. The development of a free / open source version of BSD was bogged down in the American courts, the GNU Hurd project had been running for several years but it seemed unlikely to be completed any time soon (and still doesn’t), Andrew Tanenbaum’s Minix was incomplete and at the time, sold only under a restrictive licence.

Linus initially called his kernel Freax a portmanteau word created from free, freak and Unix.

In 1992 Linus switched from his own restrictive licence to releasing Linux under the GNU General Public Licence (GPL) developed by Richard Stallman of the Free Software Foundation. This change of licencing facilitated the growth of Linux into the world wide phenomenon that it is today.

Image history.ps.png

Figure 3 - UNIX/Linux time line.

4.3. Exercises.

Research the pronunciation of "Linux" on line. Check out how Linux is pronounced by Linus Torvald.  


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