Subject:
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Re: The latest rage in pneumatic computing
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 22 Jun 2003 17:18:41 GMT
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Viewed:
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749 times
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Steve Baker wrote:
> I wonder if there are savings to be made by building the adder from scratch
> rather than out of standard XOR/AND/OR gates.
I thought so too, so I designed one. See elsewhere in this thread.
> The big remaining issue is storage - both RAM and ROM.
Yeah, I thought so too.
> Whilst you can theoretically build this out of flip-flops - and
> flip-flops out
> of standard 2 input logic gates - I can't help feeling that having more
> than
> a few dozen bits of storage would consume Lego's entire production of
> pneumatics!
>
> If you want to build something that can actually run moderately interesting
> programs, you'll need a LOT of ROM and at least a couple of bytes of RAM.
>
> If each bit could be something like an axle pushed through a hole in a beam
> with a '1' and a '0' being encoded by the amount of rod sticking out of
> the hole,
> then it would be perfectly feasible to build many hundreds of bytes of
> storage
> using only the Lego that most AFOL's have in their collections.
>
> ROM could be built identically to RAM but with fixed pegs instead of
> movable axles
>
> The question is how to address it, read it and write it.
>
> Since we can presumably build a pneumatic 'stepper motor' that would
> move a long
> stack of beams up or down one row for each change to it's input, we
> could step
> through a list of instructions stored in 'push rod' memory quite easily.
This is almost exactly what I was envisioning!!! Cool. Glad to know
I'm not the only one psychotic enough to come up with a cockamamy idea. :)
> With a counter built from a multi-stage pneumatic adder, one could
> contemplate
> building a 'jump' instruction. You're also going to need some kind of
> pneumatic 'shift-register' to hold the results of additions carried out
> with
> your one-bit adder circuit. (Either that or a LOT of those adder
> circuits!)
>
> Reading memory would require something like a bank of switches that are
> flipped
> by the push-rods or pegs that are protruding far enough.
>
> Writing RAM memory could be done by pistons forming the output of gates
> simply
> pushing against the movable axles from one side or the other of the memory
> cell.
Actually, I was thinking that what you could do is make LEGO-ish (maybe
one dimensional) "punch cards". And any program's output would be
"printed" onto another "punch card" for output. The problem with this
is that I don't see any simple way to implement this without using a
light sensor. Pneumatics can certainly push the axles out of the
holes, but I'm not sure how you'd use them to read without possibly
punching more holes in the "punch card", and losing any chance of
reading what was there in the first place.
> The question becomes one of how 'pure' you'd like to build your pneumatic
> computer and whether you consider the use of geartrains and even possibly
> electrical motors to be 'cheating'.
I'd say it's not cheating as long as you're not using the RCX or some
other microcontroller to do the work. Motors and gears are okay as long
as they are controlled by pneumatic and mechanical logic.
>> Mark
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Message has 3 Replies:
 | | Re: The latest rage in pneumatic computing
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| Using the paper tape idea - the input consists of a row of holes and spaces. The spaces are large enough for a piston end to get through, and change some part of the meachine on the other side (to store state). Output could be a piston with a sharp (...) (21 years ago, 22-Jun-03, to lugnet.robotics)
| | | Re: The latest rage in pneumatic computing
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| (...) Yes. I've been pondering this for a while. I had thought of using "long pins with friction" pressed into 1x10 technic beam. It gives you 9 holes. You'd have 8 bits plus parity (I doubt I'd use parity though) (...) Yes. Mark had proposed this (...) (21 years ago, 23-Jun-03, to lugnet.robotics)
| | | Re: The latest rage in pneumatic computing
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| <SNIP> (...) memory (...) What about 1x1 beams for a ROM punch card? Of course, combinations of 1x2 beams with 2 holes could be used, as well. For RAM (at least an all LEGO solution), I can envision a memory "drum". When bits are to be written, (...) (21 years ago, 23-Jun-03, to lugnet.robotics)
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Message is in Reply To:
| | Re: The latest rage in pneumatic computing
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| (...) I wonder if there are savings to be made by building the adder from scratch rather than out of standard XOR/AND/OR gates. (...) The big remaining issue is storage - both RAM and ROM. Whilst you can theoretically build this out of flip-flops - (...) (21 years ago, 22-Jun-03, to lugnet.robotics)
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