Mechanical Computer – Basic Mechanisms in Fire Control Computers (1953) [video] | Hacker News Reader

Mechanical Computer – Basic Mechanisms in Fire Control Computers (1953) [video]

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63 pointsxept12 comments

This video may be useful for teaching kids arithmetic intuition from non-traditional angles, including for negative numbers. E.g. the double-rack-pinion adder and especially the X-Y rack multiplier.

Multiplication is typically modeled using repeated addition, or surface areas. But when negative numbers are involved, it may be unclear. You can stick to areas if you have a Cartesian plane where the upper left and lower right quadrants are understood to contain negative area. But that may seem arbitrary, requiring explanations that seem like hand waving if you don't already have an intuition for it. The mechanical multiplier replaces hand-waving explanations of sign with a waving arm that clearly reverses slope under the right geometric conditions, to produce a positive or negative number.

I've watched this video countless times throughout the years. It's a lovely illustration of what can be calculated by physical means, but also a great example of a concise and engaging educational video - every step is clearly animated and you understand how each component works. Fantastic stuff

Though this video isn't among them, the Prelinger Archives at The Internet Archive have a thousands of public domain videos— many are educational videos from this era. They've got a streaming preview player but you can easily download larger versions directly, or torrent them if you want to save Brewster a bit of bandwidth.

https://archive.org/details/prelinger

Every time I see this video posted I watch it again from start to finish. Amazing what could (can!) be done with purely mechanical components.

That is true. And also I see a direct link between coupled mechanics and reactive programming.

That vid brought a few internal chats about computing. Since it's clear those things are computing advanced function in real time (with noise though), streaming physical changes downto the linkage graph, no side effects if you haskell-squint hard.. digital computers are a different take on computing, they were timeless, memoryfull at first.. and along the decades it seems we were all seeking to bring back automatic coupling (reactive recomputation) on the foreground.

There are concepts of electronic computers that involve streaming data in a vaguely similar way:

https://en.wikipedia.org/wiki/Systolic_array

An early example of this (an electronic computer in the 1940s!) seems to have been:

https://en.wikipedia.org/wiki/Colossus_computer

Yes most analog "computers" were time ordered / streaming.

Hollerith and discrete calculating machines were more about unordered data analysis. Static batch of input, chunk it the way you want, forward, backward.. doesn't matter. Very freeing in a way. I can understand why digital computation wiped the market, no noise and no constraint.. how nice. Until it starts to produce spaghetti bowls and crawling insects.

I love the idea of alternative reality and what if the vacuum tubes were never invented, the same with the transistor. Would we have huge steam engines running building sized mechanical computers to calculate simple programs. Each time I visit the Computer History Museum I think of what if the path was disrupted somehow.

I'd prefer to think that in the alternate universe, the machines aren't building-sized.

In that alternate universe, maybe Swiss watchmakers are the ones driving innovation in computing.

Opening a smartphone is reminiscent of opening a wristwatch.

As a fun exercise add erosion into the picture as a memory mechanism. Then just imagine a river flowing, rocks tumbling, birds chirping...

Sorry for offtopicness- xept could you please email hn@ycombinator.com? I want to send you some repost invites.

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