[HN Gopher] Lego Mechanical Computer
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Lego Mechanical Computer
Author : shakna
Score : 196 points
Date : 2024-01-10 13:10 UTC (1 days ago)
(HTM) web link (www.drmoron.org)
(TXT) w3m dump (www.drmoron.org)
| Aardwolf wrote:
| Here's something I'm wondering: Is it possible to create
| mechanical logic gates that do not involve any friction,
| elasticity, springs, gravity, as well as any active powered
| control, but only frictionless motions.
|
| Example: a NOT gate is trivial to make without any such friction
| mechanics, just a lever (one side goes up, other goes down, so
| 'NOT') or two gears (one rotates one way, the other the other
| way).
|
| But an AND or OR gate, needed to make the universal NAND or NOR
| gate to get any arbitrary logic, seem to always require some kind
| of elastic band, spring or gravity based mechanism to return the
| gate to initial position.
|
| Friction / elastic bands, etc... cause wear and tear, which is
| why it'd be interesting to see a mechanism that's as frictionless
| as the NOT gate described above.
|
| Things that are fine to use according to what I mean above would
| be: gears (including non-circular shaped ones), planetary gears /
| differential, levers, ... An example of something that is not
| fine is: an OR gate made by two sticks that can push an object
| forward, and an elastic band (or gravity or spring) makes the
| object move backwards again in the case both sticks are retracted
| backwards.
|
| I mean theoretically, there's always friction in gears anyway but
| I don't mean avoiding that one.
| speps wrote:
| Steve Mould did one with water: https://youtu.be/IxXaizglscw
| Aardwolf wrote:
| This one uses gravity though! Not the same thing as friction
| causing wear and tear, but still a similar dependency on a
| force as the springs/elastic bands. Plus use of gravity means
| a lot of force is needed to operate many of the gates at the
| same time
| xaellison wrote:
| ok but gravity scales quite nicely as force right?
| VikingCoder wrote:
| And he did one with spintronics:
|
| https://www.youtube.com/watch?v=QrkiJZKJfpY
| jncraton wrote:
| There is a large amount of theoretical research on the subject
| of energy limits in computing. For example, Landauer's
| principle states any irreversible change in information
| requires some amount of dissipated heat, and therefore some
| energy input [1].
|
| Reversible computing is an attempt to get around this limit by
| removing irreversible state changes [2].
|
| [1] https://en.wikipedia.org/wiki/Landauer%27s_principle
|
| [2] https://en.wikipedia.org/wiki/Reversible_computing
| gliptic wrote:
| Rod logic seems to fit the bill (https://anthony-
| zhang.me/blog/rod-logic/).
| nicbn wrote:
| Check out: https://m.youtube.com/watch?v=kQeDnFUNW-Q
|
| And gate starts at 4:49. Or gate starts at 6:27. The trick is
| to make some gears not stationary, moving along as other gears
| push them.
| gene-h wrote:
| Springs do not have to wear out. If springs are made from a
| material such as steel that has a fatigue limit and the stress
| they experience is less than the fatigue limit, they may be
| deformed forever.
|
| As for the answer, it appears to be yes. It is possible to make
| logic gates which only use rigid rotary links[0].
|
| [0]https://arxiv.org/abs/1801.03534
| munificent wrote:
| OR is easy: a rod that is fixed to stay horizontal but can
| slide up and down. There are rods under it at either end for
| the two input bits. If either input goes up, the horizontal
| result rod goes up.
| dekhn wrote:
| Check out https://en.wikipedia.org/wiki/Billiard-ball_computer
| It's theoretical but there are some great ideas in the general
| area of mechanical reversible computing.
| quickthrower2 wrote:
| Or gate could be a ratchet in your gear example.
|
| On a bike, it moves if you have momentum OR you pedal.
|
| I guess the ratchet needs a spring though? Doh!
| SillyUsername wrote:
| Flip flop represented as a stick is genius, should be obvious,
| but looking at at a level of electronics, isn't. IMHO that is
| stepping back/out of the box thinking.
|
| A flip flop is a circuit whose design only exists because
| electric on its own can't be held in a fixed representational
| state, whereas a stick obviously can!
| xeonmc wrote:
| reminds me of the use of redstone blocks as flipflop in
| minecraft
| dandelany wrote:
| Excitingly, the next version of Minecraft will have a single
| block (Copper Bulb) that effectively works as a redstone
| T-flip-flop! Previously it has always required a handful of
| other blocks to implement one.
| 0x3444ac53 wrote:
| Yes!! I'm super excited about this. I always implement
| flipflops with a monostable circuit and a Redstone block.
| The copper bulb will make building out large circuits soooo
| much easier.
| prettyStandard wrote:
| I just want a regular Lego computer...
|
| https://www.youtube.com/watch?v=uMhX1yZhu3A
| mbork_pl wrote:
| I'd prefer this one:
| https://www.youtube.com/watch?v=6wBrOV2FJM8
| pmayrgundter wrote:
| Love this! I once had a go* and failed.. this is really a step
| forward.
|
| I think there's an important general principle about the
| role/capabilities of the external driver/operator that's party
| addressed here in the blog and video. You can see in the video a
| somewhat complicated manipulation to step the computer through
| one cycle and the author says:
|
| "Because there is this feedback loop between memory and control
| logic, you need a fairly careful timing mechanism so that the
| output of the control holds steady long enough to set the
| appropriate state of the memory. That said, this control
| mechanism is basically missing from my computer. Instead, it
| relies on the operator (me) performing several different motions
| in the correct order to advance to the next state (as you can see
| in the video with me flipping several controls)."
|
| This is importance bc it has to do with the thermodynamics of
| work. The more intelligent the operator, the less work efficient
| (less intelligent, so to speak) the computer need be. I'm
| impressed with the level of efficiency here.. his hand motions
| are rote and not particularly delicate.
|
| The mechanism I had tried was to push a lego "program" (a flat
| block with protrusions) thru an "interpreter" (a chute with
| friction gears to drive a system of switches actuated by the
| program block's protrusions). This meant the driver was just a
| "push" of the program, which drove the system. Much nicer in
| theory, but also way harder and so didn't work. I also didn't
| have an interpreter of any sort. I had a few-bit display driven
| by the levers, so it was really just an analog machine.
|
| Anyways, if anyone's playing with this, that's a suggestion for
| one area to focus.. to simplify the role of the operator to the
| point where there's no intelligence being used.. ideally just
| linear or rotational force.
|
| * I was once into Quines and thought I was hot stuff after
| writing a self-printing program that also played the Game of
| Life[sg]. At work we had a table of legos, and I foolishly bet
| some colleagues I could build a self-printing program running on
| a lego machine. But the the computer is no simple feat itself.
| I'm now freshly inspired. I'd been exposed to the idea of a latch
| in school, but wasn't clear until now how important it is for
| state and control of the interpreter. [sg]
| https://github.com/pablo-mayrgundter/freality/tree/master/fu...
| mungoman2 wrote:
| This is awesome. I dream of a mechanical computer that can be
| 3D-printed in one go, fully assembled. A subset of all linkages
| and joints can be printed this way. Is it possible to build a
| computer out of them?
| klyrs wrote:
| Somebody's figured out the gates already...
|
| https://www.nature.com/articles/s41467-019-08678-0
| fentonc wrote:
| I came pretty close: http://www.chrisfenton.com/the-turbo-
| entabulator/
| hyperluz wrote:
| I like these explicit and "transparent" computers. Does anyone
| know of a similar computer using LEDs as logical gates in a way
| we can "see" what and how things are being computed?
| k2enemy wrote:
| Enjoy! https://megaprocessor.com/index.html
| sabartonn wrote:
| I understand that every P-N junction emits radiation as a
| byproduct. I always thought that if we could observe the
| right part of the spectrum, it should be possible to "see"
| the transistors in a processor die light up as it computes.
| The fact that nobody's done this (that I'm aware of) probably
| means it's probably not practical.
| primitivesuave wrote:
| I had a go at this concept as well, over a decade ago [1]. I used
| rubber bands to collect energy from the mechanical movement so
| the gate could be reset, but this would ostensibly require larger
| and larger forces to operate more complex gate architectures.
|
| 1. https://keshav.is/building/lego-logic-gates/
| kloch wrote:
| It's so cool to see someone actually try to build their silly
| daydream.
|
| When I was about 12, in the early 1980's when consumer VCR's were
| hot "new" tech, I imagined building a giant purely mechanical
| (except for I/O) VCR. The thing I imagined was huge - it was
| about 50ft wide x 100ft long x 50ft tall and would have used tape
| about 6 feet wide. The size was apparently due to the limitations
| of mechanical modulation of permanent magnets used to record and
| the bandwidth required to record video. Don't ask me how playback
| was supposed to work with passive magnets but I think the idea
| was very sensitive paramagnetic heads amplified mechanically by
| some absurd degree. There was lots of mechanical differential
| signal processing in this idea.
|
| This wasn't some passing daydream. Over at least six months I
| became increasingly obsessed with the idea of figuring out if it
| was even possible to build though I _never_ had any intentions of
| actually building it. What I was obsessed with is figuring out
| _how_ or _if_ you could build such an outrageously impractical
| device.
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