From: ronda@panix.com (Ronda Hauben)
Subject: On the Early History of Unix and Unix Tools(pt1of5)draft
Date: 11 Jan 1996 00:05:32 -0500
Organization: PANIX Public Access Internet and UNIX, NYC
An earlier draft of this article was posted in Summer 1994. I have
finally gotten to do further work on the draft and welcome
comments. It will be part of the netbook "Netizens: On the History and
Impact of the Net".
Thanks for any comments, suggestions, etc.
Ronda
rh120@columbia.edu
---------------
On the Early History and Impact of Unix
Tools to Build the Tools for a New Millenium
by Ronda Hauben
rh120@columbia.edu
(Part 1 of 5)
"When the barbarian, advancing step by step, had discovered
the native metals, and learned to melt them in the crucible
and to cast them in moulds; when he had alloyed native
copper with tin and produced bronze; and, finally, when by a
still greater effort of thought he had invented the furnace,
and produced iron from the ore, nine tenths of the battle
for civilization was gained. Furnished, with iron tools
capable of holding both an edge and a point, mankind were
certain of attaining to civilization."
Lewis Henry Morgan
"When Unix evolved within Bell Laboratories, it was not a
result of some deliberate management initiative. It spread
through channels of technical need and technical contact....
This was typical of the way Unix spread around Bell
Laboratories....I brought out that little hunk of history to
point out that the spread and success of Unix, first in the
Bell organizations and then in the rest of the world, was due
to the fact that it was used, modified, and tinkered up in a
whole variety of organizations."
Victor Vyssotsky
"UNIX is a lever for the intellect."
John R. Mashey
Iron Tools and Software Tools
Our era is witnessing the birth of an important new technology,
different from any in the past. This new technology is the technology of
software production. The new tools of our era are tools that make it
possible to produce software. Unlike the tools forged in the past,
software tools are not something you can grab or hold. Similarly the
processes required to develop this new technology are new. Knowing the
details of how such new tools have been created will make it possible to
better understand the promise they present for our times and for the
future.
Describing a previous technological leap, the American
anthropologist Lewis Henry Morgan called the production of iron "the
event of events in human experience....Out of it," he wrote, "came the
metallic hammer and anvil, the axe and the chisel, the plow with an iron
point, the iron sword; in fine, the basis of civilization which may be
said to rest upon this metal." Morgan maintained that until the human
species had mastered the skills and methods necessary for forging iron,
social development had been paused awaiting the achievement of this next
necessary technological advance. "The want of tools," he wrote,
"arrested the progress of mankind in barbarism. There they would have
remained to the present hour, had they failed to bridge the chasm."
Frustrated by the lack of knowledge about how iron was invented, Morgan
lamented, "It would be a singular satisfaction could it be known to what
tribe and family we are indebted for this knowledge and with it for
civilization."(1)
We are more fortunate than our ancestors. We can know some of the
details of whom to credit for the technological achievements of the
computer revolution. Documenting their contributions while many of the
pioneers are still alive will provide future generations with knowledge
of whom they are indebted to for this new and stunning advance. Like the
invention of iron, the technology of software production promises to make
possible an important new level of civilization. Such knowledge will also
help those who want to build on what has already been achieved.
Creating a Technology of Software Development
In Introduction to Computer Science, Alan Perlis, one of the early
pioneers of computer science, observed that the nature of computer
programming is too often misunderstood. "Although computer programming is
often inaccurately considered an art," he wrote, "it is actually an
infant technology."(2)
Like Morgan, Perlis believed that the progressive and accelerating
ability to use and produce tools represents a defining element in the
advance of human society. He observed that the rapid increase in the
ability of the human species to use and mold new tools was guided by two
laws. The first law describes the rapid increase in the number of people
who can wield the tools and in the number of tools available. The second
describes how the rapid development of tools to create tools guarantees
the continuing expansion of the ability to use the tools. Perlis wrote:
"First, the increase in the population trained to use tools
and in the number of tools available for their use implies
that the potential for tool utility grows as a product rather
than as a sum. Second, the amount of composition -- that is
the number and uses of tools to produce new tools -- grows as
a part of the product and assures an even greater overall
growth in tool use."(3)
Among the tools Perlis saw coming into common use "are those which
perform automatically at great speed, and whose management must perform
in the same way. Here," he explained, "the computer is essential because
of the need for quick response."(4)
The Creation of Time-Sharing
The development of the modern computer raised the question of how to
manage its operation more efficiently. An important solution to the
problem of computer management proposed in 1959 was the sequential and
automatic interspersing of many tasks known as time-sharing.(5) Among the
earliest time-sharing systems were those developed at MIT. By 1963, there
were two versions of the Compatible Time Sharing System (CTSS) operating
at MIT on two IBM 7094 computers, one at the Computation Center, and
another at MIT's Project MAC.
Those using the early time-sharing systems at MIT and elsewhere soon
discovered the delights of interactive computing made possible by time-
sharing.(6) Describing the advantages of interactive computing, time-
sharing pioneers Robert Fano and Fernando Corbato, wrote:
"For professional programmers the time-sharing system has come to
mean a great deal more than mere ease of access to the computer.
Provided with the opportunity to run a program in continuous dialogue
with the machine, editing, `debugging' and modifying the program as
they proceed, they have gained immeasurably in the ability to
experiment. They can readily investigate new programming techniques
and new approaches to problems."(7)
The results of this programming flexibility led both to a bolder and
more flexible approach to problem solving and to undertaking new areas of
research. Fano and Corbato reported that users not only would build on
each other's work, but also they would come to depend more and more on
the computer to facilitate their work. The most surprising development
that they encountered, however, was the fact that the users themselves
created many of the programming commands used in the system, instead of
needing professional programmers. While at the conventional computer
installation, they noted, "one hardly ever makes use of a program
developed by another user, because of the difficulty of exchanging
programs and data," in the Project MAC time-sharing environment, "the
ease of exchange has encouraged investigators to design their programs
with an eye to possible use by other people. They have acted essentially
as if they were writing papers to be published in technical journals."(8)
Fano and Corbato envisioned that time-sharing systems would
have a profound impact on the future. "Communities will design
systems," they predicted, "to perform various functions --
intellectual, economic and social -- and the systems in turn
undoubtedly will have profound effects in shaping the patterns of
human life."(9) "The coupling between such a utility and the
community it serves," they discovered, "is so strong that the
community is actually a part of the system itself." They foresaw
the development of a symbiotic relationship between the computer
systems and its human users which "will create new services, new
institutions, a new environment and new problems." Among these,
they proposed, would be the question of access. "How will access
to the utility be controlled?" they asked, "To what ends will the
system be devoted, and what safeguards can be devised for its
misuses? It is easy to see," they concluded, "that the progress
of this new technique will raise many social questions as well as
technical ones." (10)
Others during this period were concerned with the impact the
computer would have on current society. For example, John McCarthy
predicted that, "The computer gives signs of becoming the contemporary
counterpart of the steam engine that brought on the industrial
revolution."(11) Unlike the steam engine, however, the utility of the
computer was dependent on the successful development of software programs
written to direct it. Therefore, along with the increasing speed and
capacity of computer hardware, came the increase in the demand for and in
the cost of software. By the mid 1960's, the U.S. government was spending
increasing amounts of money to create programs to utilize computer
resources. The U.S. government, wrote McCarthy, "with a dozen or so big
systems serving its military and space establishments, is spending more
than half of its 1966 outlay of $844 million on software."(12)
Pointing out the need for studying the processes of programming,
McCarthy observed, "What computers can do, depends on the state of the
art and the science of programming as well as on speed and memory
capacity."(14) Computer pioneers like McCarthy recognized that the
computer was more than an efficient bookkeeping machine. There was a need
to discover what new applications were possible, and to create these new
applications. Therefore, there would be a need for breakthroughs in the
process of programming software. McCarthy believed that it was important
for the user to be able to program in order to realize the potential of
the computer. He pointed out that programming was a skill that was not
difficult to learn, and that it was more important to understand the task
being automated than to master programming languages. "To program the
trajectory of a rocket," McCarthy offers as an example, "requires a few
weeks' study of programming and a few years' study of physics."(14)
These early explorations in time-sharing prepared the foundation for
an important development in the process of creating software. Once the
discovery was made that simple programming tools could be created to aid
in the process of software development, and that such tools could help
those who understood the tasks to be automated, a needed leap could be
made in how to develop software. Such a program was to be carried out by
research programmers and developers at Bell Labs in the 1970's and early
1980's, building on the principles developed by the pioneers of time-
sharing and Project MAC.
The Multics Collaboration
In 1964, MIT joined with GE and AT&T in a project designed to
implement time-sharing by developing a new computer and a new operating
system. The joint research project among GE, MIT, and AT&T was created to
extend time-sharing techniques from a pilot program into a useful
prototype for the future information utility.(15) The researchers
realized that there was no existing computer that would meet the demands
of time-sharing. Therefore part of the goal of their collaboration was to
make it possible to develop a new computer as well as a new operating
system.
The collaborative project was called Multics [Multiplexed
Information and Computing Service] and was to be implemented on the GE
645 computer.(16) Technical leadership of the project included F. J.
Corbato from MIT and V.A. Vyssotsky from Bell Labs. "One of the overall
design goals is to create a computing system," they wrote, "which is
capable of meeting almost all of the present and near-future requirements
of a large computer utility. Such systems, must run continuously and
reliably 7 days a week, 24 hours a day in a way similar to telephone or
power systems, and must be capable of meeting wide service demands: from
multiple man-machine interaction to the sequential processing of
absentee-user jobs..."(17)
The goal of the research was to produce a prototype time-sharing
system. Berkley Tague, one of the Bell Labs researchers involved in the
Multics project writes, "The Multics Project was a joint project of Bell
Labs, the GE Computer Systems Division, and MIT's Project MAC to develop
a new computer and operating system that would replace MIT's CTSS system,
Bell Labs BESYS, and support the new GE machine."(18) Though AT&T
withdrew from the project in 1969, the joint work achieved significant
results. Summarizing these achievements, Tague writes, "Multics was one
of the seminal efforts in computing science and operating system design.
It established principles and features of operating system design that
are taken for granted today in any modern operating system."(19)
The Need for Operating System Research at Bell Labs
Even though AT&T withdrew from the research collaboration on
Multics, computer scientists at Bell Labs wanted some way of continuing
the advanced form of programming research that their work with CTSS and
Multics had made possible. As early as 1957, Bell Labs had found they
needed an operating system for their inhouse computer center which was
then running lots of short batch jobs. Describing the situation then
facing the Labs, Vyssotsky explains, "We just couldn't take the time to
get them on and off the machine manually. We needed an operating system
to sequence jobs through and control machine resources."(20) The BESYS
operating system was created at Bell Labs to deal with their inhouse
needs. When asked by others outside the Labs to make a copy available,
they did so but with no obligation to provide support. "There was no
support when we shipped a BESYS tape to somebody," Vyssotsky recalls, "we
would answer reasonable questions over the telephone. If they found
troubles or we found troubles, we would provide fixes."(21)
By 1964, however, Bell Labs was adopting third generation computer
equipment and had to decide whether they would build their own operating
system or go with one that was built outside the Labs. Vyssotsky recounts
the process of deliberation at the time, "Through a rather murky process
of internal deliberation we decided to join forces with General Electric
and MIT to create Multics." He explains that the Labs planned to use the
Multics operating system, "as a mainstay for Bell Laboratories internal
service computing in precisely the same way that we had used the BESYS
operating system."(22)
(to be continued)
-----------------------
This draft for comment is Chapter 9 of the draft netbook
Netizens: On the History and Impact of the Net
http://www.columbia.edu/~hauben/netbook
Notes to the draft can be found there.
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Subject: On the Early History of Unix and Unix Tools(pt2of5)draft
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Draft for Comment
On the Early History and Impact of Unix
Tools to Build the Tools for a New Millenium
by Ronda Hauben
rh120@columbia.edu
(Part 2 of 5)
Unix Is Born and the Introduction of Pipes
When AT&T made the decision to pull out of the Multics
collaboration, they took the research operating system off their GE 645
computer and put up the GECOS operating system. Though GECOS was adequate
for applications, it was "nowhere near as satisfactory if you were trying
to do things that were technically difficult and imperfectly defined,"
explained Vyssotsky, "which is the main task of research."(23)
For the pioneering work of Bell Labs research programmers like Ken
Thompson and the research purposes of the Labs, an operating system more
like what Multics had promised was needed. Along with the advantages of
immediate feedback which time-sharing provided, the Bell Labs researchers
wanted to continue the ability to work collaboratively which time-sharing
had made possible.
"What we wanted to preserve," one of the creators of Unix, Dennis
Ritchie writes, "was not just a good programming environment in which to
do programming, but a system around which a fellowship could form. We
knew from experience that the essence of communal computing, as supplied
by remote-access, time-shared machines, is not just to type programs into
a terminal instead of a keypunch, but to encourage close
communication."(24)
Ritchie describes how an informal group led by Thompson had begun
investigating alternatives to Multics before the GE-645 Multics machine
had been removed from the Labs.(25) Thompson and Ritchie presented Bell
Labs with proposals to buy them a computer so they could build their own
interactive, time-sharing operating system. Their proposals weren't acted
on. Eventually, Thompson found a little used PDP-7 computer. According to
Vyssotsky, the orphaned PDP-7 computer was a machine, "more in the class
of a Commodore 64 than the class of a PC-AT."(26)
Ritchie, Thompson, and Rudd Canady, who had been part of the Multics
project, applied the lessons they had learned to the design of a file
system for an experimental operating system. Writing on a chalk board,
they created a file system design based on "the particularly simple way
of viewing files that was suggested by the Multics I/O system."(27)
"Soon," Ritchie recounts, "Thompson began implementing the paper
file system (perhaps `chalk file system' would be more accurate) that had
been designed earlier." Thompson was eager to get a working model so he
could test it out. He proceeded to create the other aspects of an
operating system. "A file system without a way to exercise it was a
sterile proposition," notes Ritchie, "so he [Thompson] proceeded to flesh
it out with the other requirements for a working operating system, in
particular the notion of processes."(28)
Describing the primitive conditions that Thompson faced, Ritchie
writes, "At the start, Thompson did not even program on the PDP itself,
but instead used a set of macros for the GEMAP assembler on a GE-635
machine."(29) A paper tape was generated on the GE 635 and then tested on
the PDP-7 until, according to Ritchie, "a primitive Unix kernel, an
editor, an assembler, a simple shell (command interpreter), and a few
utilities (like the Unix rm, cat, cp commands) were completed. At this
point, the operating system was self-supporting, programs could be
written and tested without resort to paper tape, and development
continued on the PDP-7 itself."(30)
Ritchie describes how Thompson's PDP-7 assembler was a model of
simplicity. "There were no libraries, no loader or link editor," he
writes, "the entire source of a program was presented to the assembler,
and the output file -- with a fixed name -- that emerged was directly
executable."(31) Once the assembler was completed, "the system was able
to support itself. And thus the operating system we now call UNIX was
born," notes Ritchie.(32)
Among the other active contributors during this period were
Bell Labs researchers Rudd Canady and Joe Ossanna. The
researchers were anxious to continue their work on a more
advanced computer than the PDP-7. However, their efforts to get
AT&T to buy them a more advanced computer for their time-sharing
research hadn't succeeded. With the help of Ossanna and another
Bell Labs researcher Lee McMahon, they were finally able to
convince management to buy them a new PDP-11 computer. To obtain
this agreement, though, the researchers promised to create a text
processing system. Doug McIlroy explains that "typists everywhere
were seen as potential customers of the promised document-
preparation program. Only later did Ossanna spot the patent
department as a ripe candidate. By then there had already been
clients in the telephone-operations business."(33) By Spring
1971, the Bell Labs Unix pioneers had a text formatter,
fulfilling their promise. They had translated one they had
created for the PDP-7 from a program McIlroy had written in the
BCPL language while working on Multics. The text formatter was an
assembler program for the PDP-11.(34)
One of the important developments in Unix was the introduction of
pipes. Pipes had been suggested by McIlroy during the early days of
creating Unix. Ritchie explains how "the idea, explained one afternoon on
a blackboard, intrigued us but failed to ignite any immediate action.
There were several objections to the idea as put....What a failure of
imagination," he admits.(35) McIlroy concurs, describing how the initial
effort to add pipes to Unix occurred about the same time in 1969 that
Ritchie, Thompson and Canaday were outlining ideas for a file system.
"That was when," he writes, "the simple pipeline as a way to combine
programs, with data notationally propagating along a chain of (not
necessarily concurrent) filters was articulated."(36) However, pipes
weren't implemented in Unix until 1972. "Thanks to McIlroy's
persistence," Ritchie writes, "pipes were finally installed in the
operating system (a relatively simple job), and a new notation was
introduced."(37) Several of the old commands had to be changed to make
them usable with pipes, notes Ritchie. Summarizing how pipes found their
way into Unix, Vyssotsky notes that Thompson put them in, but "it was
McIlroy who said, `look you ought to do it.' Pipes, like most things in
Unix were not a radically new idea."(38) He describes how similar ideas
had appeared in other languages like SIMULA as early as 1967.
Dick Haight, a Unix pioneer who helped develop the
Programmer's Workbench of Unix tools, was present the day that
pipes were introduced into Unix. He describes what happened:
"I happened to have been visiting the research crew the
day they implemented pipes. It was clear to everyone
practically minutes after the system came up with pipes
working that it was a wonderful thing. Nobody would ever go
back and give that up if they could help it."(39)
Also describing the day pipes were introduced, McIlroy writes:
"Open Systems! Our Systems! How well those who were
there remember the pipe-festooned garret where Unix
took form. The excitement of creation drew people to
work there amidst the whine of the computer's cool-
ing fans, even though almost the same computer ac-
cess, could be had from one's office or from home.
Those raw quarters saw a procession of memorable
events. The advent of software pipes precipitated a
day-long orgy of one-liners....As people reveled in
the power of functional composition in the large,
which is even today unavailable to users of other
systems."(40)
The Software Tool
Pipes had been created by the time the Version 3 Unix Manual
appeared in February 1973. The date listed for the creation of pipes is
January 15, 1973(41). Not only were pipes a significant addition to Unix,
but according to McIlroy, pipes made possible a subsequent important
discovery. "In another memorable event," he writes, "the unarticulated
notion of software tools, which had been bolstered by pipes, was finally
brought home by the liberation of the pattern matching program grep from
within the editor."
McIlroy describes how he asked Thompson to create a program to help
him with some work that he was trying to do. This program resulted in the
invention of the software tool `grep.' Following is McIlroy's account of
how `grep' was taken out from the editor, leading to a clearer
understanding of the notion of a software tool. He writes:
"Grep was invented for me. I was making a program to read
text aloud through a voice synthesizer. As I invented
phonetic rules I would check Webster's dictionary for words
on which they might fail. For example, how do you cope with
the digraph `ui', which is pronounced many different ways:
`fruit', `guile', `guilty', `anguish', `intuit', `beguine'?
I would break the dictionary up into pieces that fit in ed's
limited buffer and use a global command to select a list. I
would whittle this list down by repeated scannings with ed
to see how each proposed rule worked."
"The process was tedious, and terribly wasteful, since the
dictionary had to be split (one couldn't afford to leave a
split copy on line). Then ed copied each part into /tmp,
scanned it twice to accomplish the g command, and finally
threw it away, which takes time too."
"One afternoon I asked Ken Thompson if he could lift the
regular expression recognizer out of the editor and make a
one-pass program to do it. He said yes. The next morning I
found a note in my mail announcing a program named grep. It
worked like a charm. When asked what that funny name meant,
Ken said it was obvious. It stood for the editor command
that it simulated, g/re/p (global regular expression print)."
"Progress on my talking program accelerated dramatically.
From that special-purpose beginning, grep soon became a
household word. (Something I had to stop myself from writing
in the first paragraph above shows how firmly naturalized
the idea now is: `I used ed to grep out words from the
dictionary.') More than any other single program, grep
focused the viewpoint that Kernighan and Plauger christened
and formalized in `Software Tools': make programs that do
one thing and do it well, with as few preconceptions about
input syntax as possible."(42)
Grep is listed in the Manual for Version 4 Unix which is dated
November, 1973. The date given for the creation of grep is March 3, 1973,
following the creation of pipes.(43) The creation of grep, McIlroy
explains, was followed by the invention of other special purpose software
programs that could be used as tools. He writes:
"A while later a demand arose for another special-purpose
program, gres, for substitution: g/re/s. Lee McMahon
undertook to write it, and soon foresaw that there would be
no end to the family: g/re/d, g/re/a, etc. As his concept
developed it became sed, a tool of remarkable utility that
is largely unappreciated today, because it capitalizes on
the perfect familiarity with ed that was universal ten years
ago, but no more. Sed covers a lot of needs. For example,
we have never seen fit to adopt the widespread `head'
utility because `sed 10q' does just as well."(44)
What McIlroy refers to as "the unarticulated notion of
software tools...brought home by the liberation of...grep from
within the editor" has become one of the significant achievements
of the Bell Labs research work on Unix. By making it possible to
use `grep' to search for a data pattern in a file, without having
to use an editor to go inside the file, the Bell Labs researchers
discovered that they could create a plethora of software tools
to be used in varying combinations, thus facilitating the
customized application by a user, a goal sought by those doing
research in programming.(45)
McIlroy explains that the notion of "software tool" only became
articulated among the Bell Labs researchers with the publication of the
book "Software Tools" by Kernighan and Plaugher. "Still unnamed in our
circles," McIlroy notes, "until Kernighan and Plauger wrote their book,
the idea nevertheless became a guiding principle."(46) McIlroy adds that
"We were definitely building tools before K&P, though we lacked the
suggestive word."(47)
Describing how the notion of software tools helps to create an
effective programming environment, Brian W. Kernighan and Rob Pike,
authors of The Unix Programming Environment, explain that each tool is
designed to be used with other tools and achieving this end is more
important than how each is designed internally.(48) The most important
aspect considered with each tool is the function that the tool is to
have. New tools are designed once a new function is intended.
"The guiding principle," they write, "for making the
choice should be that each program does one thing. Options are
appropriately added to a program that already has the right
functionality. If there is no such program then a new program is
called for. In that case the usual criteria for program design
should be used: the program should be as general as possible, its
default behavior should match the most common usage and it should
cooperate with other programs."(49)
Thus Unix, according to Kernighan and Pike, created "a
new style of computing, a new way of thinking of how to
attack a problem with a computer. This style," they explain,
"was based on the use of tools: using programs separately or
in combination to get a job done, rather than doing it by
hand, by monolithic self-sufficient subsystems, or by
special-purpose, one-time programs."(50)
The philosophy of using software tools that developed from
research in Unix is outlined in the "Foreward" to the special
issue of The Bell System Technical Journal published in 1978,
on "The Unix Time-sharing System." Describing the principles
which they have found to be an important component of the Unix
philosophy of software design, the researchers write:
"UNIX utilities are usually thought of as tools -- sharply
honed programs that help with generic data processing tasks.
Tools were often invented to help with the development of
UNIX programs and were continually improved by much trial,
error, discussion, and redesign, as was the operating system
itself. Tools may be used in combination to perform or
construct specific applications."(51)
They explain that a distinctive style evolved as part of
Unix research. "Unix software works smoothly together;
elaborate computing tasks are typically composed from loosely
coupled small parts, often software tools taken off the
shelf."(52)
"Sophisticated tools to make tools have evolved," they
observe. (53) Software development tools such as "nroff"
and "troff" were created. Not only was it important to create
tools, but soon tools to create tools, like "yacc" and "lex",
were developed. "Yacc" and "lex" were used to create numerous
little languages and applications like eqn and awk that greatly
enhanced the popularity of Unix.
The evolution of the tool "diff" created by McIlroy, a commonly used
software tool, is an example of how tools were continually improved,
based on the experience gained using them. McIlroy reports how he based
his work on algorithms created by others and then he tried three
different algorithms before settling on the one finally used.(54) Other
Unix tools were created through a similar process. Each program was
created to fulfill some simple capability and was called a tool. The
programs were designed to be fun to use and to be helpful to programmers.
Among the principles guiding the toolbuilders were:
"(i) Make each program do one thing well. To do a new job,
build afresh rather than complicate old programs by adding
new features.
(ii) Expect the output of every program to become the input
to another, as yet unknown, program. Don't clutter output
with extraneous information. Avoid stringently columnar or
binary input formats. Don't insist on interactive input.
(iii) Design and build software, even operating systems, to
be tried early, ideally within weeks. Don't hesitate to
throw away the clumsy parts and rebuild them.
(iv) Use tools in preference to unskilled help to lighten a
programming task, even if you have to detour to build the
tools and expect to throw some of them out after you've
finished using them."(55)
"Our goals throughout the effort," write Ritchie and
Thompson, in describing the research objectives of their work on Unix,
"when articulated at all, have always been to build a comfortable
relationship with the machine and to explain ideas and inventions
in operating systems and other software." (56)
Frederick P. Brooks Jr is another computer pioneer who recognized
the importance of pipes and combining single function programs into
what he calls "a unified programming environment" to make the
work of programmers more productive. Brooks describes Unix as one
of "the first integrated environments to come into widespread
use," which "improved productivity by integral factors."(57)
In explaining how such an environment functions, he writes:
"They attack the accidental difficulties that result
from using individual programs together, by providing
integrated libraries, unified file formats, and pipes and
filters. As a result, conceptual structures that in
principle could always call, feed, and use one another can
easily do so in practice." (58)
Following the development of single function software tools
which could be used together via pipes in a programming
environment, came the development of whole toolchests and
workbenches of tools to rationalize the work of programmers.
(to be continued)
------------------------------
This draft for comment is Chapter 9 of the draft netbook
Netizens: On the History and Impact of the Net
http://www.columbia.edu/~hauben/netbook
Notes to the draft can be found there.
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Subject: On the Early History of Unix and Unix Tools(pt3of5)draft
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Draft for Comment
On the Early History and Impact of Unix
Tools to Build the Tools for a New Millenium
by Ronda Hauben
rh120@columbia.edu
(Part 3 of 5)
Open Source Code and the Early Development of Unix
Since the Unix programming environment was used by the
researchers themselves, they came to learn its weaknesses and
problems and were encouraged to make needed improvements.
Contributing to the value of Unix during its early
development, was the fact that the source code was open and
available. It could be examined, improved, and customized.
In an article "Can UNIX Survive Secret Source Code?", Mike Lesk,
then a Bell Labs researcher, observes how only when computer
source code is open and can be modified, will it be developed and
vibrant. He gives the example of COMIT, the string processing
language. At one point, its owners decided there would no longer
be any modifications in the code, and so only distributed it in
binary form. "You haven't heard of COMIT since," he notes. He
describes how the same fate befell TRAC, a language close to
FORTH. "Software is more attractive to hackers," Lesk maintains,
"if it can be changed. As more and more UNIX suppliers restrict
access to source code, fewer and fewer advanced research shops
will be attracted to UNIX."(59)
Commenting on the importance of open source code in the
early years of Unix development at Bell Labs, Thompson and
Ritchie write, "Because all source programs were always available
and easily modified on-line we were willing to revise and rewrite
the system and its software when new ideas were invented,
discovered, or suggested by others."(60)
Not only was the source code open and available to the Bell
Labs researchers developing the system, but the Labs also made
the sources available on tape at the request of academic
colleagues. Robert Fabry of the University of California at
Berkeley was able to get a tape of Version 4 Unix and that began
the long and important role played by faculty and students at the
University of California at Berkeley in the development of
Unix.(61)
Source code tapes were made available to interested
researchers in the academic and computer science community for a
nominal fee. For example, when John Lions, a Professor of
Computer Science at the University of New South Wales in
Australia read a paper published by Thompson and Ritchie in mid
1974, he wrote them for a copy of the Unix tape. After signing a
license agreement with the Labs, and a token payment of $110
Australian ($150 U.S.), the Unix Edition 5 tape and manuals
arrived, "as a late Christmas present," in December, 1974,
remembers John Lions.(62)
While Bell Labs made the tape and manuals available,
they did so with no support. Berkley Tague explains the
release was "`caveat emptor' - i.e. dollars on the table up
front and no support promised."
Henry Spencer, a Unix pioneer from the University of
Toronto in Canada, and one of the programmers of C News,
describes how early users of Unix in the academic community
had to provide their own support. He explains:
"It was very common at the time. This was in the
days when UNIX was still treated by the Bell System
as, `Oh, just something we happen to do for our own
internal use. You can have a copy if you want, but if
you got problems, don't bother us.' And the result
was if you wanted UNIX support you did it yourself
or it didn't happen."(63)
Lions agrees, "We needed help," he notes, "but we
couldn't get any from outside sources so we ended up
generating our own expertise."(64) Not only did those working
on Unix implementation at the University of New South Wales
have access to the code, but Lions explains how Ian Johnstone,
the tutor working with him in his Operating Systems class,
suggested making some of the code for the Unix kernel available
to the students in his class. "I think it was in 1975,"
remembers Lions, that Ian Johnstone asked, "`Why don't we run
off a few of the source files for the kernel and ask the students
to take a look at them? Then we can ask them some questions;
maybe it will be interesting'."(65) Lions took Johnstone's
suggestion and made some of the Unix source code available to his
class, but his students complained. They felt they needed to see
the source code for the whole kernel in order to make sense out
of any part.
Taking their suggestion, Lions decided to make a large part of the
source code available to his class. "The following year," he recounts, "I
prepared a booklet containing the source files for a version of Edition 6
UNIX that could then run on a PDP-11/40 system." Lions followed the book
of source code with a book of "explanatory notes that was intended to
introduce students to the code."(66) Lions explains that working on his
book, "`A Commentary on the UNIX Operating System' was a real learning
experience. By slowly and methodically surveying the whole kernel he
notes, "I came to understand things that others had overlooked."(67)
When he read the manual and wasn't quite certain about his
interpretation, Lions would read the code. Through this process,
he was able to determine that the manual was "really quite
accurate in its description of what a program actually does. In
the Thompson/Ritchie era," he observes, "words were carefully
chosen."(68) Lions writes, "In our opinion, it is highly
beneficial for students to have the opportunity to study a
working operating system in all its aspects."(69)
"Moreover," he adds, "it is undoubtedly good for students majoring
in computer science to be confronted at least once in their careers with
the task of reading and understanding a program of major dimensions."(70)
Lions found that, "On the whole the authors of UNIX, Ken Thompson and
Dennis Ritchie, have created a program of great strength, integrity and
effectiveness," which he urged his students to "admire and seek to
emulate."(71) Not only did students in Lions' class read and study the
Unix source code and Lions' Commentary on the source code, but Lions
describes how he sent more than 200 copies of his book to Bell
Laboratories. Eventually, the Labs took over distribution of the book.
Tague relates how Lions' book of commentary and the
Unix source code were used at AT&T "as part of the documentation
package for those who wanted to understand or modify the UNIX(r)
source code that the USG [Unix Support Group] shipped."(72)
Even after Unix V6 had been replaced by Unix V7, Tague explains
that Lions' Commentary continued to be useful as an introduction
to Unix. Tague writes:
"It outlined the conceptual architecture, very clearly in
the short form of the system before it had accreted all the
minor changes and feature additions that disguised the
original clarity of its structure. All new people were given
a copy when they joined the USG. And I suspect most
development groups did the same."(73)
Pioneers like Henry Spencer describe how important it was to
those in the Unix community to have the source code. He notes how
having the sources made it possible to identify and fix the bugs
that they discovered, "There is something the UNIX community has
always been fairly strong on," he explained during an interview,
"admitting things you know don't work about the software." Even
in the late 1970's and early 1980's, remembers Spencer,
"practically every UNIX site had complete sources."(74)
One of the early functions of Usenet, the early online community
of Unix systems begun in 1979, according to Spencer, was to provide
cooperative software support for the Unix community. He elaborates:
Well, for one thing, Usenet predated a lot of company bbs's
and the like. It was basically a cheap way to hear about
things fast and this was at a time when practically every
UNIX site had complete sources and so a bug report often
came with a fix. It was a way of finding out what people had
discovered and what fixes they'd worked out for it. Quickly
and easily. And for that matter, if you ran into something
that you couldn't solve yourself, putting out an inquiry to
a bunch of fairly bright people who were fairly familiar
with the code, often got a response, `O Yeah. We solved that
one' or `You're right. There's a bug. Here's how to fix it'
or sympathy even if no one had a fix for it."(75)
Another Unix pioneer, Dick Haight, corroborates the
important role open source code played for those in the Unix
community:
"That by the way, was one of the great things about UNIX in
the early days: people actually shared each other's stuff.
It's too bad that so many sites now have purposefully turned
off the read privileges in order to keep their ideas from
being stolen. Not only did we learn a lot in the old days
from sharing material, but we also never had to worry about
how things really worked because we always could go read the
source. That's still the only thing that matters when the
going gets tough."(76)
Unix was continually used and improved by its creators. A growing
community of programmers, system administrators, and users, both at
Bell Labs and at academic and research sites outside the Labs, also
used, developed and debugged the code. The fact that the source code
was open and available made this possible. The result was the
creation of Unix as a powerful and flexible programming environment.
Though Unix was primarily designed to "help build research
software," Bell Labs software developers soon found that, "what
worked well in the programming laboratory also worked well on
modest projects to develop minicomputer-based systems in support
of telephone company operations."(77)
(to be continued)
----------------------------
This draft for comment is Chapter 9 of the draft netbook
Netizens: On the History and Impact of the Net
http://www.columbia.edu/~hauben/netbook
Notes to the draft can be found there.
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Subject: On the Early History of Unix and Unix Tools(pt4of5)draft
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Draft for Comment
On the Early History and Impact of Unix
Tools to Build the Tools for a New Millenium
by Ronda Hauben
rh120@columbia.edu
(Part 4 of 5)
AT&T Automates Internal Operations
In the late 1960s, there had been an upsurge in demand for
telephone company service which taxed all AT&T's resources.
The 1970 annual report of AT&T described the crisis:
"The company concluded that the convergence of a number of adverse
factors contributed to the crisis, including an unforecasted rapid
upsurge of demand for business traffic on a poor switching system,
faulty trunk maintenance and administration, inadequate training of
maintenance personnel and poor main distributing frames
administration."(78)
Section 1 of the U.S. Communications Act of 1934 charges the Federal
Communications Commission (FCC) with promoting a "rapid, efficient,
nationwide and worldwide wire and radio communications service with
adequate facilities at reasonable charge."(79) This legislative
obligation put pressure on AT&T to create and support the Bell Labs
efforts to push forward the forefronts of computer science, since the
most advanced technology and science were needed for AT&T to meet its
obligations as a regulated communications utility.
Under pressure from both the New York Public Service
Commission (NYPSC) and the FCC, AT&T had to find a way to upgrade
their service.(80) In response to these requirements, a push
began within AT&T to "use the computer to support the operation
of the Bell System Network."(81) Berkley Tague, who would be
instrumental in implementing this change at AT&T, describes
the broad scope of the effort that AT&T instituted to deal with
the service crisis. He lists: "Monitoring and alarms, maintenance
and staff management, inventory and order control, revenue data
collection and billing, traffic measurement and control, circuit
provisioning,(82) etc." and he provides the following illustration:
"The data that has to be collected to bill for calls was
being stored on a variety of media -- e.g. paper AMA tape, a
punched paper tape a few inches wide, IBM compatible mag
tape, and probably a few others. These tapes had to be
mounted, saved, trucked to DP centers for processing,
etc. They could be lost or damaged in the handling. An
obvious solution was to send the data over datalinks -- our
own network -- to the DP centers. Minicomputer-based
systems were designed to collect, preprocess and
transmit this data in some cases; in others, the
electronic switches themselves were programmed to do the
job. The goal was to eliminate the need for people
handling physical media -- a process that is both expensive
and error-prone."(83)
Software was needed to facilitate these changes. Tague explains
how the Unix system, originally created for computer research, also
served the needs of program developers. "The difference," he explains,
distinguishing between the needs of researchers and the concerns of
developers involved "support, stability and reliability." He describes
how developers have to meet deadlines and so only tolerate absolutely
necessary changes to the system. A researcher, on the other hand,
according to Tague, will "tolerate a fair amount of upset and
change and revision if it advances the toolkit significantly,
even if it means you must recode your work."(84)
The use of Unix by developers for support operations began
in the 1972 period. Tague describes how "a number of developers
were planning to build their own operating systems - typically
their first system and often their first major programs."(85)
Having experience with Unix, he advocated Unix for the job. It was
an uphill battle to convince developers to adopt Unix when there
was no offered support and it was made up of 12000 lines of
undocumented code.
In 1973, Tague pointed out the need for a central support
group and volunteered to form the group. He was given the job.
The goal of the USG which Tague created in September 1973 was to
"provide the stability and support that would buffer developers
from the experiments that researchers were daily imposing on the
evolving UNIX system." He describes how Dennis Ritchie promised
him a portable version of Unix, which was delivered as promised
by October, 1973.(86) Recoding the Unix kernel from assembler
language, which was specific to each computer, into the C
programming language, was an important feat. Once the Unix kernel
was coded in C, it would become possible to implement Unix on
different computers without having to rewrite the majority of the
code.
The effort to make Unix machine independent was desirable, so that
AT&T wouldn't be dependent on any one vendor for its computer hardware or
software or service. He explains, "A goal of my effort was to remove the
vendor lock so we could get competitive bids on the volume buys when we
deployed these mini-based systems across the Bell System."(87)
Every project adopting Unix, Tague reports, added their own features
and function to it and it became the responsibility of the USG to choose
among or merge the variations. The University of California at Berkeley,
according to Tague, performed a similar job with the variations of Unix
developed by academic computer scientists outside of AT&T.
Creating a Programmer's Workbench
While Tague was working on Unix Support Operations, other Bell Labs
researchers were planning another major project that would impact on
software development and on the use of a new form of tool.
Rudd Canaday (who had designed the original Unix file system
with Thompson and Ritchie), Dick Haight, Ted Dolotta, John Mashey,
and others formed the Programmer's Workbench Group (PWB) within the
Business Information Systems (BIS) project.(88) Tague explains that
the "BIS problem was to get a common `workbench' that would drive
code onto any of the three or four commercial vendor's mainframes
that was used by BIS." Tague writes that "By putting a UNIX(r)
system in front of the large mainframe systems, developers got the
advantages of UNIX(r) in developing code and a place they could
store debugged standard command sequences that drove development
and testing on the target mainframes."(89)
David Nowitz, a Unix pioneer who helped with the development
of UUCP, and then went on to collaborate in the creation of
honeydanber uucp, explains that when he hired into Bell
Labs in 1969, there were programmers working on many different
computers with different languages.(90) The problem these
different computers represented for those at AT&T, is described
by Haight:
"We had a real problem to solve at the time. For one thing,
we had a fairly large group of software developers at the
Labs working on several different main frames. The biggest
group, of course, consisted of people working on the IBM
360s or 370s. The programmers working on the IBM 360 or 370
had to contend with batch processing and IBM's Job Control
Language (JCL) problems. Other programmers were working with
the UNIVAC and another group with xerox computers. Only a
few were using early but expensive time sharing like TSO
(IBM's timesharing) and Univacs Remand Service."(91)
"These systems," Haight relates, "not only offered very
different programming environments, but proved to be very
expensive to use and very unfriendly." Describing the task they
were charged with, Haight continues, "Basically, we ended up trying
to give all these people a cheap text-editing front end that they
could use for interactive program entry. For that to happen, we
needed to develop a programming environment that was consistent
with what they already were using."
They developed a software subsystem which included five
components that all of the programmers working on the different
computers could use. The subsystem which they created was called
the PWB. It included RJE (Remote Job Entry), an editor, a program
for tracking version changes, a word processor and software to
simulate test input.(92) Haight believed that Unix was "the best
program development system around" and that this "development
environment notion was the very concept that got PWB going back
in '73."(93)
The vision of the PWB/UNIX was conceived of in mid April
1973 and installed on the first workbench machine in October 1973
on a PDP 11/45. By 1977 the PWB was serving 1000 users.(94) The
programmers working on the PWB rejected the top down software
design philosophy, i.e. of creating a fully integrated facility
and implementing it, and then making it available to users.
Instead they adopted a bottom up philosophy. They designed
independent single function tools and made them available to
users as early as possible. Users were encouraged to provide
feedback. The PWB programmers had the actual feedback to help
them determine what modifications were needed to improve the
tools. Evan Ivie, a Bell Labs researcher who was one of the
creators of the PWB, describes why the PWB/UNIX group adopted the
bottom up philosophy of software design:
"The idea of designing and building a complete and fully
integrated workbench system was rejected for a number of
reasons, not the least of which is the fact that no one
knows what that system should look like at this point in
time. Instead, every effort was made to identify some of the
immediate needs of potential users and to develop pieces of
the workbench that could satisfy those needs quickly. This
approach provided the workbench designers with much valuable
user feedback quickly, and it allowed the projects to start
picking up pieces of the Workbench to satisfy their most
critical needs immediately and thus to start a phased
transition to the complete workbench."(95)
The design for implementing Unix on the IBM System/370 was
done in 1979, coding was done in 1980, and by early 1981, the
first production system IBM 3033AP was installed at Bell Labs
at Indian Hill. Unix had been suggested as the development system
for programmers for the switching system software for the 5ESS
switch because the Programmer's Workbench provided "editors,
source code control and software generation systems."(96)
In 1981, after a production Unix system was running on an
IBM 3033AP in Indian Hill, the application software tools were
ported from the PDP-11/70 computer to the 3033AP. Shell
scripts were carried over and then users were transferred.(97)
By 1984 the largest user of the Unix system for the
IBM System/370 was the development project for the 5ESS Switch.
The creation at AT&T Bell Laboratories of software for
the 5ESS switch required millions of lines of code.(98) The Unix
operating system with the Programmer's Workbench software was
chosen for the 5ESS switch software development project because
the researchers felt that Unix "provided a better development
environment than any other operating system available. In
addition, the developers were all trained in using
this system and all the software tools had been developed."(99)
The elaborate process of applying Unix to the IBM 3033AP is
described by the researchers:
"Over 300 tools, written in both C and shell command
language, were identified and examined. After careful study,
almost half of the tools were found to be little-used and
were eliminated for porting to the 3033AP. The C programs
required recompiling to generate objects that would run on a
3033AP; in general, they compiled without problems. The
shell scripts were carried over with almost no problems.
(After testing) System testing, which consisted primarily of
generating the system software for the 5ESS switch was then
done. The effort to port the application tools was small and
again proved the strength and computer independence of the
UNIX operating system and the associated application
programs."(100)
The rationale leading to the creation of the Programmer's
Workbench, is outlined by Ivie. He wrote:
"Although the computer industry now has some 30 years of
experience, the programming of computer-based systems
persists in being a very difficult and costly job. This is
particularly true of large and complex systems where
scheduled slips, cost overruns, high bug rates, insufficient
throughput maintenance difficulties, etc., all seem to be
the rule instead of the exception. Part of the problem stems
from the fact that programming is as yet very much a trial
and error process."(101)
There are at this point, he observed, "only the beginnings of
a methodology or discipline for designing, building and testing
software. The situation is further aggravated by the rapidly
changing hardware industry and by the continuing evolution of
operating systems which continues to nullify much of the progress
that is made in the development of programming tools. What can be
done," he asked, "to move the programming industry toward a more
professional and stable approach to software development?"(102)
After enumerating several of the alternatives, he explained that his
proposal involved "a very different approach to improving the development
process." His recommendation was "... that the programming community
develop a program development `faculty' (or facilities) much like those
that have been developed for other professions (e.g. carpenter's
workbench, dentist's office, engineer's laboratory)." Such an approach,
he explained, "would help focus attention on the need for adequate tools
and procedures; it would serve as a mechanism for integrating tools into
a coordinated set; and it would tend to add stability to the programming
environment by separating the tools from the product (the current
approach is equivalent to carpenter's leaving their tools in each house
they build)."(103)
The Business Information Systems Programs (BISP) area of Bell
Labs which was to use the Workbench program had among the computers
it used: an IBM 370/158 and 168, a Univac 1108 and 1110, two Xerox
Sigma 5's and several minicomputers.(104) The Workbench
encouraged the development of machine independent programming
tools. "Each tool must now function," Ivie explained, "for
programmers developing code for a number of different vendor
machines. There is no room for shortcuts which are dependent on
the idiosyncrasies of a given machine (or a given project.) One
is thus forced into a more stable and generalized software
development approach which should be more applicable to new
machines."(105)
Summing up the rationale of the Programmer's Workbench
philosophy, Ivie wrote that "the programming profession has yet
to produce a software development methodology that is sufficiently
general so that it can be transferred from one project to another
and from one machine to another." With the development of a
Programmer's Workbench, he hoped, "a machine dedicated to the
software development and maintenance function can serve as a
vehicle for the development of such a methodology."(106)
(to be continued)
------------------------------
This draft for comment is Chapter 9 of the draft netbook
Netizens: On the History and Impact of the Net
http://www.columbia.edu/~hauben/netbook
Notes to the draft can be found there.
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Subject: On the Early History of Unix and Unix Tools(pt5of5)draft
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Draft for Comment
On the Early History and Impact of Unix
Tools to Build the Tools for a New Millenium
by Ronda Hauben
rh120@columbia.edu
(Part 5 of 5)
Rationalizing the Process of Software Production
In their article published in Scientific American in 1966, Fano and
Corbato noted that the creation of a working computer in 1944 was
followed by a series of quantum leaps in both the speed of the
electronics and the development of special languages which facilitated
human-computer communication. In another article in the same special
issue of Scientific American, John McCarthy identified the importance of
being able to program for making use of the computer. He also noted that
spending time mastering a programming language was less important than
understanding the functions the software is to serve. Their descriptions
demonstrate that the computer is an all-purpose machine that can be
directed to do whatever tasks humans can conceive of programs to
describe. This poses a dilemma. Since humans are still needed to
create the directives for the computer, the challenge raised is
how can the process of programming be made more rational and
productive.
Perlis had observed that the technical progress of a society
was marked by the development of tools and the ever developing
set of people capable of wielding those tools. He noted the
continuing evolution of the process of producing tools. In the
evolution of Unix, the need for software tools became evident and
a series of tools was developed to meet these needs. The creation
of time-sharing and the development of Unix as a time-sharing
system has helped to create a community of people who not only
use Unix, but who also continue its development. The
contributions to the evolution of Unix by researchers at Bell
Labs and then by those at the University of California at
Berkeley, and other users and programmers around the world who
continued the development of Unix, are an important achievement
in the development of the process of software creation.
Writing in 1975, one of the team of researchers creating the
PWB, P.J. Plauger, observed that "building on the work
of others is the only way to make substantial progress in any
field."(107) Describing the process of creating software tools,
Plauger explained that each tool is a small programming project
requiring anywhere from a few man months to a few hours to
complete. He proposed that these tools need to be designed in a
standard way so that they can interface with and be combined in a
useful way with other tools for a variety of different purposes.
"The programmer working this way becomes a tool builder, and his
impact extends far beyond the task he may originally have set out
to solve," he concluded.(108)
Placing the creation of software tools into the broader context of
tool production provides a basis to evaluate the achievements and
problems of this new stage. Sigvard Strandh, in the History of
the Machine, describes how mechanical hand tools had acquired a
stable form at an early stage. "From the Middle Ages until the
era of industrialism," he writes, "the tools of the carpenter,
joiner and smith remained more or less the same." With the
publication of the Great French Encyclopedia (between 1751 and
1780), by Diderot and d'Alembert, however, Strandh observes that
the development of these tools was given a substantial boost.
Publication of the descriptions of the tools used in all the
trades extent at the time, in great detail, in the Great French
Encyclopedia, made it possible for those interested to learn how
to build the tools, "so as to establish himself in one of the
trades described."(109)
The publication in the Great French Encyclopedia made
possible the constant improvement of the old hand tools, and thus
made it possible to manufacture the new tools needed for the new
technical developments. "Industrialization," Strandh writes,
"means the manual methods of manufacture are mechanized, that is,
taken over by machines. The machine tool is the local outcome of
the process. Mass manufacture of machine tools," which he writes,
"has been called 'the industry of industries', didn't become
widespread until the 1870's."(110)
The conditions described by Strandh made possible advances in the
technology of tool production in the 19th Century. These conditions
provide a helpful perspective when examining the achievements of the Unix
community in developing the software tool creation process. Bell Labs
researchers early on recognized that software production required text
editing in place of soldering, and that this substitution represented a
significant challenge. The creation by Bell Labs programmers of software
tools, making it possible to produce better software more efficiently, is
an important development. This development is similar to the ability to
improve hand tools that Morgan documents as the technological advance
represented by the invention of iron. The success of writing the code for
the 5ESS switch at AT&T demonstrates the achievement these software tools
have made possible.(111)
Generating software is different from creating hardware and it
presents a particular challenge. You can't see software tools or touch
them or handle them as you can mechanical tools. "Software is invisible
and unvisualizable," Brooks points out, since "the reality of software is
not inherently embedded in space." Therefore, he observes, "In spite of
the progress made in restricting and simplifying the structures of
software, these structures remain inherently unvisualizable and thus do
not permit the mind to use some of its most powerful conceptual tools.
This lack not only impedes the process of design with one mind, it also
severely hinders communication among minds."(112)
Therefore, there is a particular problem posed when creating,
describing, or representing software tools. Diderot was able to catalog
the tools and industrial processes of his times, but such a task is much
more difficult when it comes to creating such an encyclopedia or
presentation of software tools, or in creating the software component
catalog that McIlroy once proposed. The development of UUCP and then
of Usenet, as a means of cheap communication among those of the Unix
community, made it possible to surmount some of the difficulties inherent
in the process of software production.(113)
The Usenet community was able to pioneer the creation of a
cooperative network that helped facilitate communications among the Unix
software community. "Though large institutions have been able to avail
themselves of communications networks such as ARPANET, the UNIX community
has made inexpensive electronic communication available to all its
members via Usenet," remarked John Stoneback, a faculty member at
Moravian College, in an article describing the important role
that Unix played for members of the academic community.(114)
Describing the importance of the creation of the Unix communication
program UUCP, McIlroy writes that "before uucp remote login was the only
kind of electronic connection between Unix systems. With uucp, every PDP
11 with dial-up (not even dial-out) access became connected. E-mail and
file transfer previously available only among the fortunate few sites
on ARPANET, were democratized overnight. This was the brainchild of Mike
Lesk."(115) Lesk's original plan in creating UUCP was to create an
automatic software updating system.(116) That, however, was fraught with
difficulties, and instead, with modifications to UUCP by David
Nowitz, it became the basis for a broad ranging online computer
network that came to be called Usenet. McIlroy, describing how
uucp was used by Tom Truscott and other Usenet pioneers to create
an online community, writes, "Soon Truscott saw that the new
medium could be used for automatic dissemination of information,
and netnews was born."(117)
The Unix system is based on a methodology that helps the
user to learn the new language. The methodology is similar to the
way children learn to talk. As Unix pioneers Brian Kernighan and
John Mashey, write, "The code that people see, adapt, and imitate
is usually well structured. People learn to code well in the same
way that they learn to speak their native language well by
imitation and immediate feedback."(118)
"People often look at each other's code," they explain,
"comment on it in person and through interuser communication
facilities, and take pieces of it for their own use. The ideas of
programming teams and egoless programming fit into the Unix
environment well, since they encourage sharing rather than
isolation." (119) Given the frequent sharing and building on each
others code, though, "some programs have always been `owned' by
one or two people, many others," however, they note, "have been
passed around so much that it is difficult to tell exactly who
wrote them...." Also, they point out that "Tools have been built
to automate many common programming tasks."(120)
Kernighan and Mashey explain how in its early days, up
through 1974, "Unix best supported a single, cooperative, tightly
coupled group of people on each machine." By 1975, the PWB/UNIX
made possible support for a larger number of users. They describe
how there have been large groups of over 200 users working on
different machines, but that users preferred "to share a machine
so they could share procedures and data bases."(121) They
describe how the concept of software tools spread from the Unix
Programming environment and PWB/UNIX to more generalized
applications described by Kernighan and Plauger in their book
Software Tools (1976), then to further applications that were
ported to other machines, and then to the more generalized
applications of the Lawrence Berkeley Laboratory (LBL).(122)
Documenting Technological Progress
In writing about the role that technology plays in the
development of society, Morgan observed that oral or written
documentation helps to facilitate technological progress.
Morgan described how the Greek poet Homer by documenting the
civilization that existed prior to his times, provided future
generations with a yardstick by which they could measure their
own accomplishments.(123)
So, too, documentation of the achievements of the Unix pioneers and of
the tools they created, is an important step to be taken by those
wanting to understand the progress made in our times. When
amateur scientists created the Royal Society in Great Britain in
the 1660's, one of their early efforts was to invite Rev. Spratt
into the Society and to support him to write a history of the
documentation of technology from Homer to their own times.
Diderot's work on the Great French Encyclopedia, in the years
leading up to the French Revolution, played such a role
summarizing the knowledge, including, most importantly, the
summary of all the trades and industries with their tools
existing up to his time in France.
Unix pioneers often emphasize that scientific progress can only be
made by building on what has already been achieved. It is important,
therefore, to recognize the legacy of how Unix made it possible to
achieve programming projects involving millions of lines of code by
creating a workbench of software development tools. The creation of a new
form of tool requires a new form of tool production process and
though such technology is only in its infancy, there are examples
to be studied to know what we are building on. As Henry Spencer
and Geoff Collyer recognized when they were working on increasing
the performance of Netnews software, it was necessary to
systemmatically record what was happening to be able to see what
progress was being made, "To know how to get somewhere, you must
know where you are starting from."(124) Similarly, it is
important to systemmatically document the history of the
significant developments of the software tool revolution, so that
there will be a yardstick by which to measure the accomplishments
and to determine the new questions to be explored.(125)
-----------------------------------
[Research for this article was begun as part of an Independent Study in
Spring 1994 at the University of Michigan Dearborn on Unix tools with
Dr. Narasimhamurthi. It was good to take a course which made possible
not only doing some interesting and important research, but also where
it was possible to design and use the tools that Unix has made possible
to help with the research. Begun to help commemorate the 25th anniversary
of Unix in 1994, further work on the article was done during Summer 1995.
Thanks to Doug McIlroy, David Nowitz, John Lions, and Berkley Tague for
making available information that was helpful in doing the research for
this article and thanks to Doug McIlroy, Alfred Aho, Tom Truscott,
Eric Allman and Mark Horton for commenting on earlier versions-
Ronda rh120@columbia.edu]
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This draft for comment is Chapter 9 of the draft netbook
Netizens: On the History and Impact of the Net
http://www.columbia.edu/~hauben/netbook
Notes to the draft can be found there.
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