Interestingly, several months ago I came across the following 1953 training video dealing with this same subject.
Gears of war: When mechanical analog computers ruled the waves
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Re: Gears of war: When mechanical analog computers ruled the waves
#12Obligatory link to youtube video of a 1950s training video on the mechanical fire control computers (which I stole from HN last time this sort of topic came up): https://www.youtube.com/watch?v=s1i-dnAH9Y4 edit: This video is the same footage featured throughout the article, in fact.
Ah... You beat me to it!
Re: Gears of war: When mechanical analog computers ruled the waves
#13off topic, but did anyone pay attention the Juniper deception force adds they sport?
This line of one commercial just blew my mind: 'the less they know, the safer they are' ...can a security oriented company actually get away with saying that?!
Re: Gears of war: When mechanical analog computers ruled the waves
#14Some of these analogue computers are pretty amazing things.
I can kinda get my head around slow moving ships being tracked by a mechanical computer, but the Russian ZSU-23-4 Shilka self propelled anti-aircraft artillery vehicle used an electro mechanical gun aiming computer in the 60s and 70s.
A mechanical computer that can track a supersonic rapidly manoeuvring jet aircraft by radar, and adjust the aim of its guns quickly enough and accurately enough to score hits. It's amazing what can be achieved.
Re: Gears of war: When mechanical analog computers ruled the waves
#15Earlier quoted context omitted.
Yep, it's embarrassing that this got published. Did the author just forget about mechanical tolerance? The random motion of molecules? Ambient sound waves? Electromagnetic noise? I suppose it's forgivable that the author didn't think of these things but they should have run their technical article past a subject expert before publishing it. This isn't a nitpick, they screwed up the core concept of their article! > th…
Make a circuit "digital" does not automagically make it more accurate, and you cannot "add bits" to a datatype to make your measurement more accurate. Before a digital circuit can process a signal, it must first be quantized, an inherently analog process. Your digital data is only as good as your analog signal, plus inherent quantization noise[1]. In addition, any mixed-signal IC represents a design compromise betwee…
Very inexpensive digital circuits can perform calculations on their inputs with much higher precision than any analog calculator ever built. Weight, volume, power, or dollars, pick your cost.
Yes, you are limited by your measurement, but you are so limited when operating entirely within the analog domain as well. Therefore it makes sense to make your measurements as accurate as possible, quantize once, and be done with it. Keeping it in the analog domain merely allows more points for noise to enter the picture.
Re: Gears of war: When mechanical analog computers ruled the waves
#16Earlier quoted context omitted.
I think you'd use all the mass in the observable universe long before the GNU Multi-Precision library started sweating :)
If you were naive. You can probably cheat (ie be more clever in your construction).
I suspect that once you had found a way to get the asymptotic cost growth under control you would find you had build a digital mechanical calculator.
Re: Gears of war: When mechanical analog computers ruled the waves
#17Earlier quoted context omitted.
Yep, it's embarrassing that this got published. Did the author just forget about mechanical tolerance? The random motion of molecules? Ambient sound waves? Electromagnetic noise? I suppose it's forgivable that the author didn't think of these things but they should have run their technical article past a subject expert before publishing it. This isn't a nitpick, they screwed up the core concept of their article! > th…
Make a circuit "digital" does not automagically make it more accurate, and you cannot "add bits" to a datatype to make your measurement more accurate. Before a digital circuit can process a signal, it must first be quantized, an inherently analog process. Your digital data is only as good as your analog signal, plus inherent quantization noise[1]. In addition, any mixed-signal IC represents a design compromise betwee…
Yes, in many circumstances it is advisable or necessary to perform calculations in front of the analog front end. Even the simplest "digital" transceiver amplifies and mixes before the AFE. However, I don't believe any of that is relevant to our criticism of the article, which focuses explicitly and extensively on performing calculations with cams, gears, and shafts at an "infinite level of resolution" and why the author thinks this is supposed to be better than digital computation:
> There are no least significant digits dropped, and answers are continuous rather than dependent on “for-next” clock-driven computing cycles.
Even if the article had talked about improving accuracy by skipping the digitizing step for gyroscopes, wind vanes, etc, his claim would not have been credible. It's not terribly difficult to digitize mechanical motion to the subatomic level (AFM is from the '80s) and many modern data sources (ring-laser gyroscopes, information acquired from remote ships and satellites) could not be coupled to the mechanical computer in a way that could be expected to beat digitization error.
A GPS chip likely has something to gain from correlating in front of the analog front end but a firing computer does not. You pay a fixed cost to go in and out of a digital representation, but with analog you keep paying for each calculation and, given that one of these firing computers weighed 3000lbs, I expect that this application saw digitization errors that were tiny next to calculation errors.
Thanks for being thorough, but I see your post as a tangental point rather than as a counterargument.
Re: Gears of war: When mechanical analog computers ruled the waves
#18Earlier quoted context omitted.
If you were naive. You can probably cheat (ie be more clever in your construction).
I suspect that once you had found a way to get the asymptotic cost growth under control you would find you had build a digital mechanical calculator.
My money would be on that as well, though not at crazy odds.