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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Mon, 23 Jun 2003 00:27:03 GMT
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Viewed:
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943 times
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In lugnet.robotics, Mark Tarrabain wrote:
> 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.
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)
>
> > 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.
Yes. Mark had proposed this and I like it a lot. Sliding the axle through an
axle hole is much easier than sticking a pin in a hole.
> >
> > 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.
I have already built a reversible stepper pneumatic motor, just with the
intended purpose of rotating memory.
>
> 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.
You can punch the cards by pushing the same direction as the holes. You could
do a non-destructive read by pressing the axles perpendicular to the holes.
>
> > 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.
I'd like to stick to pneumaticically powered stuff, but that does not restrict
me from using gears, especially with pneumatic stepper motors.
>
> > > Mark
Kevin
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Message has 1 Reply:
 | | Re: The latest rage in pneumatic computing
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| (...) Why not go the 'bit stream' route instead? Forget about bytes. Make a Turing machine operating on an 'endless' stream of bits. No adders, subtractors etc, just a state machine. Might be a bit difficult to program though... -- Anders Isaksson, (...) (21 years ago, 30-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 thought so too, so I designed one. See elsewhere in this thread. (...) Yeah, I thought so too. (...) 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. (...) (21 years ago, 22-Jun-03, to lugnet.robotics)
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