[HN Gopher] Charles Babbage's Difference Engine Turns 200
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Charles Babbage's Difference Engine Turns 200
Author : pseudolus
Score : 67 points
Date : 2022-05-29 09:39 UTC (13 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| pixxel wrote:
| A quick 5 minute video on Babbage and his engine:
| https://invidious.snopyta.org/watch?v=XSkGY6LchJs
| gurjeet wrote:
| The source, YouTube, link:
| https://www.youtube.com/watch?v=XSkGY6LchJs
|
| sed 's". _/
| watch?v=\\(._\\)"https://www.youtube.com/watch?v=\1"'
| m-i-l wrote:
| I know there's a whole genre (steampunk) dedicated to "what if
| the Difference Engine had actually been built in Babbage's
| lifetime and started a steam based computer revolution a century
| earlier than the electrical computer revolution", but I do think
| it is a fascinating idea. One sometimes overlooked aspect of this
| is the global network of telegraph cables. Within Charles
| Babbage's lifetime there were working undersea cables from the UK
| to the US (completed 1866) and from the UK to India (completed in
| 1870), with the UK to Australia cable completed in 1872 just a
| year after Babbage's death, so it is conceivable we'd have had a
| telegraph powered form of the internet a century earlier too.
| deepnet wrote:
| And Babbage patented a packet switching semaphore system using
| church steeples.
| KineticLensman wrote:
| > I know there's a whole genre (steampunk)
|
| As I'm sure you know, the classic example is 'The Difference
| Engine' [0] by Gibson and Sterling, but my favourite is 'The
| Thrilling Adventures of Lovelace and Babbage' [1] by Sydney
| Padua, which features the eponymous characters as a crime-
| fighting duo, assisted by appropriate automation. It also
| features Isambard Kingdom 'You look like you need an Engineer'
| Brunel.
|
| [0] https://en.wikipedia.org/wiki/The_Difference_Engine
|
| [1]
| https://en.wikipedia.org/wiki/The_Thrilling_Adventures_of_Lo...
| hcs wrote:
| > it is conceivable we'd have had a telegraph powered form of
| the internet a century earlier too.
|
| It's interesting to think that relays were an inherent part of
| all long range telegraphy (Morse's patent is 1840 and there
| were predecessors), but it took until the 1930s to start using
| relays to build electromechanical digital computers. The
| manufacturing technology would take a long time to catch up,
| but Boolean logic and electricity could have conceivably met a
| century earlier. (Edited 1940s to 1930s)
| Animats wrote:
| Timing.
|
| Early relays were big, not very reliable, and had too many
| adjustments. Early attempts at Teletype machines (the
| Teletype Model 12) worked the way you'd expect, with a
| rotating commutator and relays for the serial to parallel
| converter. Relay timing was not consistent and was a source
| of errors. The big breakthrough came when Howard Krum figured
| out how to make a mechanical serial to parallel converter in
| the mid 1920s. That was much easier to adjust, because all
| the timing came from cams driven by a motor. So everything
| was in sync. Teletype liked that design so much they stayed
| with it until the 1950s, then switched to a different all-
| mechanical design. Unfortunately, they stayed with all-
| mechanical too long, through the 1960s, and got left behind.
|
| Most early phone exchange systems, and IBM tabulators,
| involved camshaft-driving timing. An IBM tabulator was mostly
| camshafts and clutches. It wasn't until after WWII that all-
| relay systems, such as #5 Crossbar, finally displaced
| telephone switches with driveshafts. Bell Labs developed wire
| relays with redundant contacts that required no field
| adjustments.
|
| Railroad signalling went all-relay earlier, but they didn't
| need compute speed.
| hcs wrote:
| Certainly wouldn't have been practical without smaller,
| faster, more reliable relays, and once it got there the
| applications were immediately understood.
|
| What I meant was that it seems surprising, from a modern
| perspective, that it never seems to have even been proposed
| until much later. There are some early hints: I recalled a
| mention in Gardner's "Logic Machines and Diagrams" of an
| early (1880s) electromechanical design by Allan Marquand
| [0], who had built several mechanical logic machines. But
| Gardner wrote that there wasn't anything published on
| switching circuits as logic until 1910 in a review by
| Ehrenfest [1], and it wasn't developed until several
| independent publications in the 1930s, most influentially
| by Shannon. By then switching circuits had already gotten
| very complicated in practice.
|
| [0] pg 112 https://archive.org/details/logicmachinesdia00ma
| rt/page/112/...
|
| Alonzo Church uncovered a diagram by Marquand of a logic
| machine using relays [2], but it seems to have been
| sequential, using the relays as memory of what hadn't yet
| been disproven [3]. In 1886 Charles S. Peirce wrote to
| Marquand mentioning that electrical circuits could be used
| for Boolean addition and multiplication [4], though it
| doesn't seem he was thinking about relays, and I don't know
| that this was ever applied.
|
| [1] pg 138, reference 2 https://archive.org/details/logicma
| chinesdia00mart/page/138/...
|
| [2] Mays "The first circuit for an electrical logic-
| machine" https://archive.org/details/sim_science_1953-09-04
| _118_3062/...
|
| [3] Patterson's review of Mays,
| https://doi.org/10.2307/2964205
|
| [4] https://electronics.stackexchange.com/a/321534 , it
| seems clear to me that Peirce was talking about manual
| switches, not relays as the answer seems to suggest.
| nickt wrote:
| Tim Robinson built working copies of the Difference Engine out of
| Meccano [1] a few years ago, and is now involved with Plan 28, a
| project to build the Analytical Engine, which @jgrahamc provides
| regular updates to the Computer Conservation Society [2].
|
| [1] https://meccano.us/ [2] https://blog.plan28.org/
| Animats wrote:
| Since, after years of work, they haven't cut any metal, maybe
| they should focus on simulation.
|
| Here's an analytical engine simulator.[1] It's just doing the
| computation, but is not a physical simulation or animation with
| moving parts. The next step up would be something like this.[2]
| That's an IBM 1401 simulator in Unreal Engine, with the
| controls and tape drive movement fully animated.
|
| [1] https://www.fourmilab.ch/babbage/emulator.html
|
| [2] https://youtu.be/hvDiND0nTIY
| synu wrote:
| Wow, that is super cool. Is there an index somewhere of
| simulations of more retro technology like that?
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