History of UNIX
Fergus Toolan
Intelligent Information Retrieval
Group
University College Dublin
Administration
• Practical Attendance.
• Practical Web Site
– http://ftoolan.ucd.ie/unix/
• Lecture Notes
– Also available at web site.
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Overview
• UNIX/LINUX/SOLARIS
• Motivations for the development of UNIX.
• History of the development
• Reasons for its success over the years
• Future developments for UNIX.
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Flavours
• There are many „flavours‟ of UNIX.
• UNIX / LINUX / SOLARIS / ...
• UNIX stable scalable OS.
• Micro-kernel architecture.
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Linux
• Originally a scaled down version of UNIX.
• Now a full OS in its own right.
• Developed by Linus Torvalds
• Based on MINIX created by Andrew
Tanenbaum.
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Solaris
• Sun Microsystems
• OS for the Sun machines.
• Derivative of UNIX.
• Can be off-putting for a UNIX/LINUX
person as the commands are slightly
different.
• However if you can use 1 you can use 3.
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MULTICS
• In the mid 60‟s all computers used batch
processing systems
• An interactive “shell” was required by some
people
• Multi-tasking, multi-user systems were
necessary
• Bell Labs developed MULTICS in 1965.
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MULTICS
• Bell Labs pulled out of the MULTICS
project in 1969.
• Progress had been slow.
• Financial issues with the partners.
• Bell Labs allowed the continuation of the
Operating Systems Group.
• Thompson/Ritchie develop UNIX.
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COMP2006, UNIX Operating Systems, January 26th.
Space Traveller
• Game written by Ritchie.
• FORTRAN code for the GECOS system
• Poor graphics on GECOS.
• Thompson had access to a PDP-7 with good
graphics.
• No OS available to run the space traveller
game.
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COMP2006, UNIX Operating Systems, January 26th.
Space Traveller
• UNIX developed to run Space Traveller.
• Based on a design Thompson and Ritchie
had sketched out on paper.
• Included a file system, a process subsystem
and a few basic utility programs
• The name UNIX was coined by Kernighan
as a pun on MULTICS.
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COMP2006, UNIX Operating Systems, January 26th.
History
• 1969 can be seen as the birth of UNIX.
• However it was 1971 before it was
implemented in an actual project in Bell.
• This was on a PDP-11.
• Application development then began in
earnest for UNIX systems.
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Application
Development
• Thompson began to create a Fortran
compiler in 1971.
• However it mutated to become a compiler
for a derivative of BCPL.
• This language became known as B.
• It was interpreted. Ritchie created a
compiled version.
• C was born!
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COMP2006, UNIX Operating Systems, January 26th.
Operating Systems
• In 1973 a momentous event occurred.
• Prior to this time all operating systems had
been written in assembly languages.
• Hence hardware dependent. Difficult to
program.
• Ritchie rewrote UNIX in C in 1973.
• High-Level language.
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COMP2006, UNIX Operating Systems, January 26th.
Distribution
• By 1977 was the year that UNIX was first
ported to a non-PDP machine.
• This was a landmark achievement.
• UNIX is the first (and only??) truly portable
OS. PC‟s, Clusters, Mac, Crays,...
• In 1977 there were approximately 500
installations of UNIX in the world.
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The split
• Up to the late 1970‟s Bell Labs were the
only people developing the UNIX system.
• Academic licences had meant that
Universities were looking at it.
• The fact that the OS source code was freely
available meant that anyone could edit.
• Countless people began to develop new
utilities.
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The Split
• When the University of California –
Berkely got a copy of the UNIX OS they
began to edit the kernel.
• This lead to the split. By 1983 there were
two flavours of UNIX.
– System V – the Bell labs version
– BSD – Berkely Software Distribution
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The Success of UNIX
• By 1984 100,000 installations were in
place. Why did it succeed.
– Written in a high-level language – slower but...
– Simple UI – interactive shell, no batch
– Primitives that allow complex programs to be
built.
– Hierarchical File System
– Consistent format for files
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Success of UNIX
– Simple interface to peripheral devices – treats
all as a file.
– multi-user, multiprocess system. Each user can
execute several processes at once.
– Hides machine architecture. Cross platform
programs could be developed.
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1984 - 1991
• During this period there was little major
changes made to the system kernel. Both
BSD and System V remained static.
• However many utilities programs were
developed around the world for both
systems. What would run on one would run
on another.
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Open Source
• UNIX was born in an era with little in the
way of copy protection.
• Hence all code for UNIX was open source.
• This is beginning to change in some
installations. Red-Hat Enterprise servers.
• However SUSE, Fedora, Debian are still
open source.
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Open Source
• What did it mean?
– anyone could edit the OS.
– Most were disasters
– however some were incorporated into the
system.
– It involves rebuilding the kernel.
– Most UNIX users have strange kernel
configurations.
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The birth of LINUX
• In 1991 Linus Torvalds a graduate student
in Denmark developed a system as part of
his PhD work which he called LINUX.
• It was a simpler variant of UNIX.
• It is now the third most popular operating
systems in the world after Windows and
Mac.
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The birth of LINUX
• LINUX has been implemented on many
platforms and for different tasks from
standard desktop use to high-level servers.
• LINUX is more suited to desktop operations
than UNIX which is mainly server level.
• The main reason is in the utilities that have
been developed.
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LINUX Utilities
• X-Windows.
• Movies, Games, Music,...
• Web Browsers, E-mail clients,
• Word Processing
– including through star/open office the creation
of Word, Excel, PPT etc.
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The spread of UNIX
• In 2000 Apple made a major leap forward
in terms of the spread of UNIX.
• For the OS-X operating system (the current
standard macintosh operating system)
Apple based it on Free BSD UNIX.
• This means that UNIX has proliferated.
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• For naive users it looks like the old mac OS.
• However underneath it is an installation of
BSD 4.3 – I think!!
• This means that any application for
Macintosh, UNIX or LINUX can be run on
it.
• If we have source code even windows
applications can be run on it.
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The spread of LINUX
• Many distributions: Red Hat, Mandrake,
Suse, Debian,....
• Red Hat commercial company.
• Enterprise level services power many
servers.
• Desktop ones available for free.
• Now from Fedora – Linux returns to Open
Source.
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