Subject:
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Re: Mechanical Memory for Computing
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 1 Jul 2003 01:14:11 GMT
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Viewed:
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777 times
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In lugnet.robotics, Anders Isaksson wrote:
> Depends on what you call 'recent' :-)
>
> The DEC PDP-8 had 12-bit words with 6-bit bytes, if I recall correctly.
> There were also computers with 36-bit words containing six 6-bit bytes in
> one word (DEC 10/20?), or three 12-bit bytes.
>
> The DataSaab D21 (that's a computer from the 1950-60 something) had 24-bit
> words split into eight 3-bit bytes/nybbles/digits.
>
> In the name of internationalization, a character is now 16 bits wide, so the
> 'byte' may still grow...
>
> --
> Anders Isaksson, Sweden
I just had to join in on this one :)
I greatly enjoyed playing around with Intel's early 4004 PMOS microprocessor,
one of the very first I think. It was a 4 bit per entity (character?) device
which was primarily aimed at processing BCD, one digit at a time. After that,
numerous other 4 bit devices appeared, mainly as the "engine" in early
calculators. But Ah! it was a great day when Intel unveiled the 4040, a real
step up from the earlier 4004 :) Access to data RAM could be done in less that
12 instructions - you could do it in 7 !!
Then they invented 8 bit devices after which all the programming got almost too
easy ;) The Nat Semi SCAMP cut the memory access function to a mere 5
instructions.
But I digress, the original thread content regarding mechanical computing is
very interesting. I had tried this myself some while back and had serious
problems getting the "power" in. In order to sustain a continuous computation,
you have to find a way to feed energy into the system, especially when using
mechanical parts with the lack of precision common in Lego elements. My attempts
to couple a "clock" (shaft input from a motor attempting to complete things like
memory storage strokes), I had too much difficulty in getting different parts of
the assembly to work in accurate enough phase.
Maybe someone with more time and/or imagination might be able to come up with a
"clocked" ALU to memory/memory to ALU mechanical state transfer scheme.
JB
(showing his age with knowledge of 4 bit micros)
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Message has 1 Reply:
 | | Re: Mechanical Memory for Computing
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| (...) Hi John, I'd forgotten about the 4040. I thought they went from the 4004 to the 8008 to the 8080, but my memory must be failing me. I really only became aware of microprocessors with the 8080. I invented a clocked pneumatic scheme where you (...) (21 years ago, 1-Jul-03, to lugnet.robotics)
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Message is in Reply To:
| | Re: Mechanical Memory for Computing
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| (...) Depends on what you call 'recent' :-) The DEC PDP-8 had 12-bit words with 6-bit bytes, if I recall correctly. There were also computers with 36-bit words containing six 6-bit bytes in one word (DEC 10/20?), or three 12-bit bytes. The DataSaab (...) (21 years ago, 30-Jun-03, to lugnet.robotics)
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