Clarification of Answer by
larre-ga
on
04 Oct 2002 21:22 PDT
I'm happy to provide a summary and sample of each source for you. I
hesitate to attempt any ranking, however. I believe it would be quite
presumptions of me to attempt that sort of mind reading. I'm the
left-brain sort, rather than psychic in any way. :) The ranking is
something you'll have to decide, based upon the focus and ultimate
purpose of your need for sources.
Every source has been chosen (from 1,000's of search results) because
it is specifically germane to one or more aspects of the subject
matter at hand, and offers insight into the original question: Why are
computers digital instead of analogue? None of the sources are
offered simply as 'filler'. From this offering, you should be able to
find support in seven or eight references for just about any thesis
within the subject area. You'll also have the links and bibliographies
contained within these material for further reference and study.
Some of these resources are very "rich" in the amount of information
offered in very few words, quite quotable, as it were. Others are more
verbose. Some are contained on websites which show a great deal of web
design savvy, others are presented more starkly or simply, focusing on
the information itself, rather than its presentation. I've grouped the
sources into two general types: Analog vs. Digital, and History of
Computing - Analog TO Digital.
*** ANALOG VS. DIGITAL ***
21st Century Communication
A basic description of analog computation and the transition to
digital computing.
"Until very recently, most of the information transmitted in the world
was analog, i.e. some kind of continuous change of a certain property
like color, sound, etc. And the main reason for that is that humans
cannot perceive directly digital information, i.e. with strictly
quantatized properties like colors can be either black or white (no
gray), or something can be either on or off. Another reason was that
there were no efficient means to store, transmit and convert between
digital and analog form. With the advent of LSI and computing theory
in general, the second reason is partially solved. But why, you will
ask, we need digital at all? There is one BIG reason: any information
in digital form looks the same and can be transmitted and stored
without change and loss."
21st Century Communication
Analog vs. Digital
http://thinrope.net/misc/report021
Analog Computation
Future developments in computing processes. The present state of
analog computing and its applications to the future.
"Each new decade sees a new wave of innovative technology. Experts in
the 1950s thought that the world's computing needs could be supplied
by half a dozen computers. The 1990s saw digital processors become so
inexpensive that a car could use dozens of computers to control it.
Today just one Porsche contains ninety-two processors. According to
Paul Saffo, director of the Institute for the Future, changes just as
dramatic will be caused by massive arrays of sensors that will allow
computers to control our environment."
Analog Computation
Everything Old is New Again
http://www.indiana.edu/~rcapub/v21n2/p24.html
Digital vs. Analogue Computers
The development of analogue computing in the 1940's. Includes computer
and researcher biographies, and glossary.
"Essentially an analog computer must be able to accept inputs which
vary with respect to time, and directly apply these inputs to various
devices within the computer which performs the computing operations of
additions, subtraction, multiplication, division, integration and
function generation. ... The computing units of analog computers are
able to respond immediately to the changes which they detect in the
input variables, and the connexion of these various units in a
particular fashion can cause an analog computer to perform very
complex arithmetic functions at high speed while the actual process
under study is in operation. ...
Analog computers do not have the ability of digital computers to store
data in large quantities, nor do they have the comprehensive logical
facilities afforded by programming digital machines. And although the
arithmetic functions performed by the computing units are more complex
in analog machines than in the digital systems, the cost of the
hardware required to provide a high degree of accuracy in an analog
machine is often prohibitive."
Digital vs. Analogue Computers
http://www.computer50.org/mark1/ana-dig.html
Analog vs. Digital
"... So why shouldn't computers be analog? Well there have been a few
analog computers and devices but for the most part what sounds logical
may not be (in electronics) when you know more about the problem. Let
me explain why.
Remember, this is just a high level explanation meant to give people a
basic understanding of the concepts - all these issues are more
complex than explained, but at least this will give people the right
idea."
Analog vs. Digital
Why are Computers Digital?
http://www.mackido.com/Hardware/AnalogVsDigital.html
Still Some Value in Analog
A "technology for the masses" level explanation of specific purposes
of digital and analog devices.
"Analog is getting a bum rap.
Don't get me wrong: Digital is great. Without digital, I'd be writing
about something like tires, and nothing interesting ever happens in
that space. But as a society, we've gone ga-ga over digital while
giving analog the shaft. Anymore, it seems to be a pretty simple
equation. Digital = good. Analog = bad. Digital is a magic label that
automatically makes a product more desirable, like "imported" in the
1980s or the Good Housekeeping Seal of Approval in the 1960s."
USA Today
Still Some Value in Analog by Kevin Maney
http://www.usatoday.com/life/cyber/ccarch/cckev046.htm
Is Life Analog or Digital
A brief philosophical treatise by Dyson Freeman, whose mind seems to
live farther in the future than the rest of us. Useful for
understanding the underlying principles of the digital vs. analog
debate.
"The two ways of processing information are analog and digital. An LP
record gives us music in analog form, a CD gives us music in digital
form. A slide-rule does multiplication and division in analog form, an
electronic calculator or computer does them in digital form. We define
analog-life as life that processes information in analog form,
digital-life as life that processes information in digital form."
Is LIfe Analog or Digital
Dyson Freeman
http://www.edge.org/3rd_culture/dyson_ad/dyson_ad_index.html
Analog Computing (.pdf format, requires Adobe Acrobat Reader)
An illustrated tutorial in Adobe .pdf format. The tutorial explains
the basis for analog computing and experimentation.
"The physical world is an amazingly accurate computational device. We
can design tools to exploit this computational
power. Start with an abstract problem in need of solving. Find an
analog in the physical world. Set up the analog as a physical
experiment. Perform the experiment and examine the results."
Analog Computing (.pdf format, requires Adobe Acrobat Reader)
http://www.ai.mit.edu/projects/aries/course/notes/analog2.pdf
Can you explain the difference between analog and digital technology?
A basic Q & A definition of analog vs. digital by How Stuff Works.
"In analog technology, a wave is recorded or used in its original
form...
In digital technology, the analog wave is sampled at some interval,
and then turned into numbers that are stored in the digital device."
Differences between Analog and Digital Technology
How Stuff Works
http://www.howstuffworks.com/question7.htm
Why are Computers Digital?
Lecture notes in outline form for Computer Concepts course. Basic
precepts of analog and digital data representation. I've chosen to
link the Google cached HTML version for ease of use. An .rft version
(for word processors) is also available, linked at the top of the
page.
"Data Representation and Digital Electronics
Data representation makes it possible to convert letters, sounds, and
images into electrical signals
Digital electronics makes it possible for computer to manipulate
simple “on” and “off” signals to perform complex tasks
A digital device works with discrete data or digits, such as 1 and 0
An analog device works with continuous data such as sound waves"
Lecture Notes - Why are Computers Digital?
http://216.239.53.100/search?q=cache:fSx5R07gcfAC:https://forloop.cs.ucf.edu/cgs2100/notes/cc2-5notes.rtf+%22why+are+computers+digital%22&hl=en&ie=UTF-8&client=googlet
Analog vs. Digital
Side by side comparison of analog vs. digital data.
"Historians say we've entered a new age, the Information age. Digital
technology, the ability to represent data by a series of 0's and 1's,
is what makes the information age possible. "
Analog vs. Digital
http://radified.com/Articles/digital_vs_analog.htm
*** HISTORY OF COMPUTING - ANALOG TO DIGITAL ***
A Chronology of Digital Computing Machines to 1952
The article chronicles and details the development of the computer
from 1500 through 1952, the 'dividing line' between analog and digital
devices. Excellent bibliography included.
"The ENIAC's architecture resembles that of the Harvard Mark I, but
its components are entirely electronic, incorporating 17,468 vacuum
tubes and more than 80,000 other components. The machine weighs 30
tons, covers about 1,000 square feet of floor, and consumes somewhere
between 130 and 174 kilowatts of electricity (sources differ). Many
of the modules are made to plug into the mainframe, to shorten the
repair time when a tube or other component fails. The cost and
downtime are further reduced by using circuits designed to work even
if the components are off-specification, and wire of the type least
preferred by hungry mice in experiments.
The machine incorporates 20 accumulators (the original plan was for
4). The accumulators and other units are all connected by several data
buses, and a set of "program lines" for synchronization. Each
accumulator stores a 10-digit number, using 10 bits to represent each
digit, plus a sign bit, and also incorporates circuits to add a number
from
a bus ("digit trunk") to the stored number, and to transmit the stored
number or its complement to a bus."
A Chronology of Digital Computing Machines to 1952
http://www.davros.org/misc/chronology.html
History of Computing
"This narrative presents the major developments in the history of
computing and tries to put them into perspective."
Earliest Devices - Humanity has used devices to aid in computation for
millennia; an example is the abacus. The first machines that could
arrive at the answer to an arithmetical question more or less
autonomously started to appear in the 1600's, limited to addition and
subtraction at first, but later also able to perform multiplications.
These devices used techniques such as cogs and gears first developed
for clocks. The difference engines of the 1800s could carry out a long
sequence of such calculations in order to construct mathematical
tables, but were not widely used. "
History of Computing
http://www.wikipedia.org/wiki/History_of_computing
Analog Computer Museum
Definitions, explanations and examples of Analog computers.
"Analog computer - A computer that performs mathematical operations in
a parallel manner on continuous variables. The components of the
computer are assembled to permit the computer to perform as a model,
or in a manner analogous to some other physical system."
Analog Computer Museum - Brief History
http://dcoward.best.vwh.net/analog/analog1.htm#history
Key Events in the History of Computing
This article was prepared for the 50th Anniversary of the Eniac, by
the IEEE Society. It chronicles the development of the computer from
the abacus to the Eniac, and subsequent events.
"The bits and pieces of a computer (including the software) came
together over many centuries, many people each adding a small
contribution. One of those that was not recognized for many years was
that of Mukhammad ibn Musa Al'Khowarizmi, a Tashkent cleric who in the
twelth century developed the concept of a written process to be
followed to achieve some goal, and published a book on the subject
that gave it is modern name -- algorithm."
Key Events in the History of Computing
http://ei.cs.vt.edu/~history/50th/30.minute.show.html
Analog Computers
A definition of analog computers and examples of several general
types. More specific information available through many inline text
links.
"A form of computer using electronic or mechanical phenomena to model
the problem being solved by using one kind of physical quantity to
represent another.
Used in distinction to digital computers, in which physical or
mechanical phenomena are used to construct a finite-state machine
which is then used to model the problem being solved."
Wikipedia - Analog Computers
http://www.wikipedia.org/wiki/Analog_computer
A Brief History of Computer Technology
Overview article on the development of digital computing.
"In fact, as late as the 1960s, analog computers were routinely used
to solve systems of finite difference equations arising in oil
reservoir modeling. In the end, digital computing devices proved to
have the power, economics and scalability necessary to deal with large
scale computations. Digital computers now dominate the computing world
in all areas ranging from the hand calculator to the supercomputer and
are pervasive throughout society. Therefore, this brief sketch of the
development of scientific computing is limited to the area of digital,
electronic computers. "
A Brief History of Computer Technology
http://csep1.phy.ornl.gov/ov/node8.html
Boolean and Digital Logic
Theory of boolean and digital mathematics as applied to computers.
Adobe .pdf format. Adobe Acrobat reader is required for viewing.
"Some of the earliest electronic computers were analog devices. These
machines treated each electronic signal value (voltage) as a different
numerical value. While this might seem like a good idea, analog
computers were hopelessly error prone because a small error in
storing, retrieving, computing, or transmitting a signal was
noticeable.
Digital computers work with a finite number of ranges of electrical
signals; all of the different signal values that fell into the same
range were treated the same. For example, any signal that was between
5 and 7 volts might be treated as the integer 3. When necessary to
transmit 3, a digital device would attempt to transmit an electronic
signal of 6 volts; if a noisy communication line distorted this signal
to say 5.5 volts, it would still be treated as the integer 3.
Our computers are digital; furthermore, they use only two ranges of
electrical signals (high and low). The reasons for this are twofold.
First, two-state devices proved to be reliable, fast, and
cost-effective. Secondly, there exists a branch of mathematics that is
extremely useful in working with such devices."
Boolean and Digital Logic
http://pages.stern.nyu.edu/~ecampbel/Logic.pdf
A Brief History of Computing
Jack Copeland offers a detailed overview of analog and digital
computing history. Many links to information about Turing machines.
"What is a Computer? - Historically, computers were human clerks who
calculated in accordance with effective methods [link to The
Church-Turing Thesis: Effective Methods]. These human computers did
the sorts of calculation nowadays carried out by electronic computers,
and many thousands of them were employed in commerce, government, and
research establishments. The term computing machine, used increasingly
from the 1920s, refers to any machine that does the work of a human
computer, i.e. any machine that calculates in accordance with
effective methods. During the late 1940s and early 1950s, with the
advent of electronic computing machines, the phrase 'computing
machine' gradually gave way simply to 'computer', initially usually
with the prefix 'electronic' or 'digital'."
A Brief History of Computing
http://www.alanturing.net/turing_archive/pages/Reference%20Articles/BriefHistofComp.html
Analog vs. Digital Development
A brief history of computing, focusing primarily upon the digital age.
"Digital Information - The rise of numeric computing devices or
calculators leads to the representation of information as numbers
which allows for the application of well known numerical algorithms
for the processing of the digitized information.. The texts used for
early computing were often reprints of 19th century treatises of
numerical methods used by applied mathematicians.
The early computers were a simply an outgrowth of the use of
mechanical numerical calculators for the evaluation of formulae such
as the trajectory of artillery shells . They performed
addition,subtraction,multiplication and division."
Digital versus Analog
http://ulla.mcgill.ca/arts150b/arts150b7.htm
The Modern History of Computing
A survey of modern computer history, with emphasis on the analogue and
digital machines from 1940 to present.
"Historically, computers were human clerks who calculated in
accordance with effective methods. These human computers did the sorts
of calculation nowadays carried out by electronic computers, and many
thousands of them were employed in commerce, government, and research
establishments. The term computing machine, used increasingly from the
1920s, refers to any machine that does the work of a human computer,
i.e. any machine that calculates in accordance with effective methods.
During the late 1940s and early 1950s, with the advent of electronic
computing machines, the phrase ‘computing machine’ gradually gave way
simply to ‘computer’, initially usually with the prefix ‘electronic’
or ‘digital’. This entry surveys the history of these machines."
Stanford Encyclopedia of Philosophy
The Modern History of Computing
http://plato.stanford.edu/entries/computing-history/
Early Computing Devices
An introduction and four case studies of early computers, presented by
the Massachusetts Institute of Technology.
"When one thinks of the history of modern day computers, very often
images of the ENIAC at the Moore School of UPenn come to mind. Indeed,
the ENIAC was the first truly digital computer in the world; however,
the history of computers dates back to over a century before the ENIAC
was ever invented. Computers were in widespread use in the 1800's,
however they looked substantially different than the computers today.
The "computers" of the 19th century were typically young women and
men, hired by the thousands, to perform basic and repetitive
mathematical calculations. Over time their work became mechanized,
first by truly "mechanical computers," and then eventually by analog
and then digital computers. The first shift, however, from complete
hand calculation to the use of mechanical computing devices is
responsible for shaping modern computer devices in many ways that are
not always obvious. This website examines a few of these early
devices, showing how these early contributions to the evolution of
computing devices have shaped what we consider to be the modern
computer."
Massachusetts Institute of Technology
Early Computing Devices
http://web.mit.edu/STS001/www/Team8/introduction.htm
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I hope this helps.
larre-ga
