I've been researching some topics in the history of electronics, and as I was digging around, it crossed my mind that the word "analog" has an interesting history itself. Its definition and use changed several times during the twentieth century. In the 1989 print edition of the Oxford English Dictionary, the only engineering use of the word analog (of course, they spelt it "analogue") was as an adjective before the word "computer":
ANALOGUE --- (adjective) analogue computer, a computer which operates with numbers represented by some physically measurable quantity, such as weight, length, voltage, etc.The 2013 on-line edition has a much improved and expanded entry for the word, which includes
ANALOGUE --- (adjective) typically contrasted with digital... 1c. of signals or data: represented by a continuously variable physical quantity, such as voltage, spatial position, etc.However, in the context of circuit design and signal processing, I prefer the definition
ANALOG --- (adjective) in signals, continuous in amplitude and time; in circuit design, circuits that operate on these signals using continuous quantitiesas opposed to
DIGITAL --- (adjective) in signals, quantized in amplitude and discrete in time; in circuit design, circuits that operate on discrete-time signals using quantized (usually binary) representations.I don't insist these definitions are exhaustive or complete(1), but they draw a line in the sand for the starting point in this archaeological dig.
So, when did the meaning of "analog" change from "scale model" to its modern definition? I plan to find out. One interesting way to trace the evolution of the word is to find when it became commonly accepted enough to appear in the titles of publications, rather than in the text, where its meaning could be easily defined with a footnote or parenthetical phrase(2).
I've been digging around a little bit, and I've found some interesting things, and about which I have many comments, which I will share over the next few posts.
Spoilers:
Can't wait? Here are some early findings: The first published articles to use the word "analog" (as a noun) in the title were a pair of papers by H. H. Skilling of Stanford University in 1931:
[1] H. H. Skilling, "An electric analog of friction for solution of mechanical systems such as the torsional-vibration damper," Transactions of the American Institute of Electrical Engineers, vol. 50, no. 3, pp. 1155-1158, Sep. 1931.The first published article to use the word "analog" as an adjective in the title was published in 1948:
[2] H. H. Skilling, "Electric analogs for diffi cult problems," Electrical Engineering, vol. 50, no. 11, pp. 862-865, Nov. 1931.
[3] E. L. Harder and G. D. McCann, "A large-scale general-purpose electric analog computer," Transactions of the American Institute of Electrical Engineers, vol. 67, no. 1, pp. 664-673, Jan. 1948.The first book(3) to use the word "analog" in the title was the classic text by Korn and Korn in 1952:
[4] Granino A. Korn and Theresa M. Korn, Electronic Analog Computers. New York: McGraw-Hill, 1952.Analog Devices, Inc. was founded in 1965, see:
[5] Walt Jung, "Op amp history," in Op Amp Applications, Walter G. Jung, Ed. Norwood, Mass.: Analog Devices, 2002, ch. H, p. H.35.The first books to use the words "analog" and "circuit" in the title were published in 1972:
[6] Dan Sheingold, "Editor's notes: Analog dialectic," Analog Dialogue, vol. 30, no. 3, p. 1, 1996.
[7] Alan B. Grebene, Analog Integrated Circuit Design. New York: Van Nostrand Reinhold, 1972.If you have additional (or contradictory!) information, please leave a comment.
[8] Jacob Millman and Christos C. Halkias, Integrated Electronics: Analog and Digital Circuits and Systems. New York: McGraw-Hill, 1972.
Footnotes:
- For example, switched-capacitor filters are continuous in amplitude and discrete in time, and asynchronous digital systems do exist.
- This approach has the added bonus of being easier to research, given modern searchable databases, so it makes a good starting point (but just a starting point).
- I define "book" to mean published by a major publishing house for public distribution. Technical reports, computer manuals, and theses don't count.
9 comments:
If you want to be able to search through book content metadata the Google books project provides an ngram search tool to allow you to see the relative frequency of words in the OCR'd texts over time. I searched for analogue vs analog to get you started: https://books.google.com/ngrams/graph?content=analogue%2C+analog&case_insensitive=on&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t4%3B%2Canalogue%3B%2Cc0%3B%2Cs0%3B%3Banalogue%3B%2Cc0%3B%3BAnalogue%3B%2Cc0%3B.t4%3B%2Canalog%3B%2Cc0%3B%2Cs0%3B%3Banalog%3B%2Cc0%3B%3BAnalog%3B%2Cc0%3B%3BANALOG%3B%2Cc0
That's a really cool graph, and it basically confirms what I've found by other means ("analog" took off after WWII). Interestingly, if you add "digital" to the graph, you see that "analog" appears to be a reaction to the popularity of "digital".
Unfortunately, Google "books" includes a lot of small-distribution technical reports, computer manuals, and university theses, so it's hard to identify real books in the results.
I would be interested in your thoughts on "linear" compared to "analog" (as well as "logic" compared to "digital"). At times, I think analog/logic are good complements since they deal with computation and linear/digital are good complements since they contrast the continuity of signals. But that's not how they are typically paired. It's largely irrelevant, but interesting to pedantic types.
I balk at "linear" as a synonym for "analog" because many interesting analog circuits are decidedly nonlinear (log and exponential circuits, multipliers, RMS-to-DC converters, and other translinear blocks). However, I note that some thesauruses list "linear" as a synonym.
One on-line dictionary even defines analog as "of a circuit or device having an output that is proportional to the input", which I disagree with.
That said, I like the analog/logic pairing, but "linear" is orthogonal to these definitions in my mind (digital systems can be linear, and analog systems can be nonlinear).
'Analogue' of course comes from the same Greek root as analogy and its history is therefore pretty old. I'm certain I've seen it in rather ancient physics texts, but a cursory search in that context turns-up a first-use reference date of 1826, in French ( - within Faraday's lifetime, but not a reference to electronic engineering per se!)
http://www.etymonline.com/index.php?term=analogue
NB Same date is given by Meriam-Webster also.
[And since I've not posted before - a great blog I've enjoyed since its sad inception. Thanks Kurt!]
Hmmm, what about the science fiction magazine named "analog", was there any connection there?
> what about the science fiction magazine named "analog"
https://en.wikipedia.org/wiki/Analog_Science_Fiction_and_Fact
"In 1960, Campbell changed the title of the magazine to Analog Science Fiction & Fact; he had long wanted to get rid of the word "Astounding" in the title, which he felt was too sensational."
So: after Korn & Korn et al, within the domain of analog electronic computers (not for very long), and maybe just "a buzz-word that starts with A" (so it files the same alphabetically).
And we are talking about electronic analogs. There was a sibling, electric analogs. A panel with a lot of chokes and capacitors, and AC sources of variable phase. When large scale electric utility power networks started, they crashed and burned for mysterious reasons. Being able to scale the problem to a large workbench and try all possible energy flows with meters everywhere was an important technique. A couple universities made some coin (in the depression!) by renting time on their analogs.
Then there is the large field of Mechanical analogs. Ball and Disk integrators did the same as opamp integrators. This sure set the stage for electronic analog computing. And Ms Korn's specialty: range-scaling for lowest errors (since the dynamic range of each mechanical element was even less than a typical tube opamp).
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