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  • Cool RetroTech, but…

    Posted by David Foster on February 8th, 2012 (All posts by )

    The first stored-program electronic computer capable of doing useful work was the EDSAC, built at Cambridge University and commissioned in 1949. It supported research in several scientific disciplines as well as the development of software techniques until being scrapped as obsolete in 1958. There is now a project to rebuild this pioneering computer: the reconstructed version will be made as close as possible to the original, with one exception…and the reasons for the exception, I think, are perhaps more related to social history than to the history of technology.

    EDSAC used vacuum tubes (valves, in Britspeak) for its arithmetical and logical functions; for memory, it used something called a mercury delay line, an idea borrowed from WWII radar technology. (EDSAC=Electronic Delay Storage Automatic Calculator.) information to be stored was introduced at one end of a tube of mercury, down which it traveled in the form of pulses of sound. About 1 millisecond later, at the other end of the tank, the pulses were picked up, amplified, and emitted again at the starting point, with the whole train of information bits in the line thereby being kept in continuous circulation as long as the power was on.

    Can you guess how the reconstructed EDSAC is going to differ from the original version?

    That’s right…no mercury. “Health and safety regulations” have led to a decision that mercury cannot be used in the rebuild.

    Certainly, mercury can be hazardous when not handled carefully–see the material safety data sheet. But it’s not plutonium. It’s not even nitroglycerin. Is it perhaps an overreaction to ban the use of this substance, which would be contained in metal tubes, in a one-of-a-kind museum piece?

    Now, much of the EDSAC rebuild work will be done by volunteers–maybe even in the absence of government and/or insurance regulations, the team would have preferred to avoid the cumbersomeness of working with mercury. And I’m sure they’ll do as good a job as possible in coming up with an alternative non-mercury approach to the machine’s memory. (Maybe gin for a delay medium, as was suggested by Alan Turing for the original machine.)

    My concern here isn’t really mainly with the rebuild project per se, but rather a more general one–the growing timidity of our western societies, often enforced by regulations of one kind or another. A couple of years ago, I wrote about the Congressional suppression of passenger service on the historic steamboat Delta Queen, on fire-safety grounds–despite the fact that the vessel has been outfitted with fire detection and suppression systems, is never more than a mile or so from shore, and surely provides a vacation experience which is significantly safer than most other things people could do with the same amount of time. And throughout the US, many kinds of playground equipment…swings, jungle gyms, merry-go-rounds, for example…have been removed on safety grounds. See the boys and girls in the plastic bubble…see also, via a commenter at that post, this story about the fate of space-program-themed playgrounds constructed in the 1960s.

    The pros and cons of safety-related tradeoffs can of course be debated for individual cases, whether we’re talking about playground equipment or a computer reconstruction. But it’s hard to escape the conclusion that the general level of timidity in our societies has increased substantially, and that there is some level of such timidity that leads to individual psychological harm and to social dysfunction.

    Some countervailing forces to the drift toward timidity have arisen…see for example the free-range kids movement created by Lenore Skezany. But I’m afraid the general trend is much in the other direction.

    The EDSAC rebuild project site is here.


    7 Responses to “Cool RetroTech, but…”

    1. Jeff the Bobcat Says:

      Yet, the government is trying to mandate CFL with mercury in them. What to do if one breaks? Or to just dispose of a burned out CFL?

    2. Jason Says:

      I had recently visited the National Museum of the United States Air Force, located at Wright-Patterson AFB, OH, essentially Dayton OH.
      I’m really into aviation and spent a lot of time talking to the volunteers (who are all retired military) about the airplanes on display and there individual stories.
      We got to talking about getting a chance to sit in a display airplane’s cockpit. I was told as late as the 1980s the Museum used to have open cockpit days where visitors were able to just that. They no longer do that because of the liability involved and because of exposure to chemicals and materials in the cockpits.
      They run into the same problem when trying to restore airplanes to display. They are unable to use of instruments because the materials used to make the actual display are slightly radioactive (I don’t recall what material). This is also a problem common to the warbird community.

    3. David Foster Says:

      “the materials used to make the actual display are slightly radioactive”

      Probably radium used for a glow-in-the-dark effect. It is indeed very hazardous if you ingest it, and there were some high incidences of disease among workers who had to touch the stuff, but hard to see what harm it does just sitting there.

    4. David Foster Says:

      Found a discussion thread on the mercury issue as it relates to EDSAC here.

      Regarding the CFLs, the quantities in the bulbs are of course very small, but OTOH I’ll bet only one household in 50 actually follows the recommended procedures for disposal and breakage. I do wonder about worker safety in the lamp plants, many of which will be in places where US health and safety laws do not apply.

    5. Andrew_M_Garland Says:

      Busybodies have taken over.

      They see unacceptable risk in sitting next to a luminous dial instrument for 2 minutes.

      They see acceptable risk in limiting energy production and raising its price. Any deaths arising from this enforced poverty are “worth it” to maybe, possibly, affect global temperature by 0.1 degree.

    6. Jeff the Bobcat Says:

      Andrew, the busybodies would have a huge party if they could diffinitively prove any downward change. Any shred of legitimacy would be priceless to them.

    7. Michael Kennedy Says:

      At Duxford, in England near Oxford, the British Air Museum has warbird in which you can fly as a passenger. There is even a Spitfire trainer with second seat. I have fl;own as a passenger in a B 24, the only flying example, which is owned by a private foundation. The rules must be different.

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