Subject:
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Re: Building a computer from Lego's
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 14 Feb 2001 07:40:28 GMT
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Original-From:
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Steve Baker <sjbaker1@airmail.net!saynotospam!>
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Reply-To:
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sjbaker1@SPAMLESSairmail.net
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Viewed:
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696 times
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Lincoln Smith wrote:
>
> Sorry if this one has been suggested:
>
> http://anon.razorwire.com/lego/
Hmmm - interesting.
The two gates he presents seem a little complex and bulky.
I think the reason is the choice of representation for the
logic levels 0 and 1...and perhaps even the idea of base-2
arithmetic at all.
It seems to me that if you chose '0' to be represented by
a clockwise rotation and '1' be an anticlockwise rotation
(say), Then a 'NOT' gate becomes just two 8t gears meshed
between the input and output axles. If the input shaft
rotates clockwise (a zero) then the output shaft rotates
anticlockwise (a one).
The trouble is that I can't think of a *simple* way to build
a NAND, AND or OR gate - which you fundamentally need in order
to build some logic circuits.
However, there are all sorts of interesting gates you can
build with base-3 logic.
Using '0' == clockwise, '1' == stationary and '2' == anticlockwise,
then two gears still do something like and inverter (they turn
0 to 2 and 2 to 0 and leave 1 alone) - and something as simple
as a Lego differential can produce some interesting logic functions:
If one input shaft goes into the differential directly - and the
other is used to rotate the differential housing then the output
shaft rotates at the sum of the two speeds but in the opposite
direction.
So for the inputs:
0 0 = 2
0 1 = 2
0 2 = 1
1 0 = 2
1 1 = 0
1 2 = 0
2 0 = 1
2 1 = 0
2 2 = 0
It may be kinda tricky to figure out how to build more complex
things out of these unusual kinds of gates - but they seem to
have the richness of function that you'd need.
At any rate, I think the important thing is that both the
'0' state and the '1' state entail some kind of rotation so
that all gates can get their power from the input signal.
--
Steve Baker HomeEmail: <sjbaker1@airmail.net>
WorkEmail: <sjbaker@link.com>
HomePage : http://web2.airmail.net/sjbaker1
Projects : http://plib.sourceforge.net
http://tuxaqfh.sourceforge.net
http://tuxkart.sourceforge.net
http://prettypoly.sourceforge.net
http://freeglut.sourceforge.net
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Message is in Reply To:
 | | Re: Building a computer from Lego's
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| Sorry if this one has been suggested: (URL) have seen two others, but searches came up empty and didn't someone post a brick sorter that read in a sequence of 1x2 tiles to produce an "order" to be "picked" from hoppers of different colour? Couldn't (...) (23 years ago, 13-Feb-01, to lugnet.robotics, lugnet.general)
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