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Re: The difference between programmable and non-programmable logic--if

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On 10/23/2011 5:23 PM, Robert Myers wrote:
> On 10/23/2011 12:20 PM, kenney@cix.compulink.co.uk wrote:
>> In article<y7Ioq.5255$ZO7.5060@newsfe05.iad>, rbmyersusa@gmail.com
>> (Robert Myers) wrote:
>>
>>> What's the difference between that and "programmable?"
>>
>> The truth table for something like an And gate is deterministic. You
>> know what you are going to get out given an input. It is possible
>> (though not always practical) to write a truth table for any piece of
>> fixed logic however complex. Off course once you have the table you may
>> be able to implement it some other way. One trick in the 8 bit days was
>> to use a PROM.
>>
>
> That's more along the lines of the kind of question I was asking.
>
> If you take a *really* abstract view of digital devices, programmable or
> otherwise, they are devices that map the integers into the integers.
>
> Viewing logic that way got Godel to his famous result. I assume that
> Turing must have followed a similar path, although I'm less familiar
> with even the outlines of the proof. In such an abstract view, the
> distinction between instructions and data disappears, as I x I is
> isomorphic to I.
>
> One way to describe either hardware or software is to write out the map
> from I to I that it defines (the equivalent of your truth table). In
> practice, that is done in only the simplest of cases, as you have
> already described.
>
> Maybe you need to be a Godel or a Turing even to formulate the question
> I'd like to ask. Out of all the gigantic space of maps from I to I, we
> have chosen almost stereotyped procedures for describing those maps. The
> stereotyping necessarily limits the class of maps we can describe and
> has a profound effect on the complexity of the description.
>
> By putting "fixed-function" circuitry into a GPU, you limit the class of
> maps it can span, but you also reduce the complexity of the description
> of the maps and, in practical terms, you can usually do whatever it is
> much faster, in part inevitably because the space you are wandering
> through as you compute is much smaller (you have many fewer choices to
> make and thus many fewer gate delays).
>
> I suppose that I am trying to imagine a less restrictive, more abstract,
> way of doing business--something in the color space bounded by the truth
> table of a nand gate, an assembly language program, and the set of all
> arbitrary maps from the integers to the integers.
>
> My apologies for sounding like another frequent poster here, but I'm
> doing the best I can.
>
> Robert.
>

How does time or sequentialness enter into this abstraction?  Is there a 
difference between a shift register and a wire?

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The difference between programmable and non-programmable logic--if there is one. Robert Myers <rbmyersusa@gmail.com> - 2011-10-22 19:14 -0400
  Re: The difference between programmable and non-programmable logic--if there is one. Del Cecchi <delcecchi@gmail.com> - 2011-10-22 20:52 -0500
    Re: The difference between programmable and non-programmable logic--if there is one. Andrew Reilly <areilly---@bigpond.net.au> - 2011-10-23 03:06 +0000
      Re: The difference between programmable and non-programmable logic--if there is one. nmm1@cam.ac.uk - 2011-10-23 09:50 +0100
    Re: The difference between programmable and non-programmable logic--if there is one. Quadibloc <jsavard@ecn.ab.ca> - 2011-10-23 09:22 -0700
  Re: The difference between programmable and non-programmable logic--if kenney@cix.compulink.co.uk - 2011-10-23 11:20 -0500
    Re: The difference between programmable and non-programmable logic--if Robert Myers <rbmyersusa@gmail.com> - 2011-10-23 18:23 -0400
      Re: The difference between programmable and non-programmable logic--if Del Cecchi <delcecchi@gmail.com> - 2011-10-23 19:46 -0500
        Re: The difference between programmable and non-programmable logic--if Robert Myers <rbmyersusa@gmail.com> - 2011-10-23 21:27 -0400
      Re: The difference between programmable and non-programmable logic--if torbenm@diku.dk (Torben Ægidius Mogensen) - 2011-10-24 10:36 +0200
        Re: The difference between programmable and non-programmable logic--if Robert Myers <rbmyersusa@gmail.com> - 2011-10-24 19:01 -0400
          Re: The difference between programmable and non-programmable logic--if Robert Myers <rbmyersusa@gmail.com> - 2011-10-24 22:56 -0400
            Re: The difference between programmable and non-programmable logic--if Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-10-25 09:18 +0200
          Re: The difference between programmable and non-programmable logic--if "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-10-24 21:08 -0700
            Re: The difference between programmable and non-programmable logic--if Mark Thorson <nospam@sonic.net> - 2011-10-25 18:25 -0800
              Re: The difference between programmable and non-programmable logic--if BGB <cr88192@hotmail.com> - 2011-10-25 19:45 -0700
            Re: The difference between programmable and non-programmable logic--if Mark Thorson <nospam@sonic.net> - 2011-10-29 16:39 -0800
              Re: The difference between programmable and non-programmable logic--if BGB <cr88192@hotmail.com> - 2011-10-30 09:54 -0700
                Re: The difference between programmable and non-programmable logic--if Stefan Monnier <monnier@iro.umontreal.ca> - 2011-10-30 13:50 -0400
                Re: The difference between programmable and non-programmable logic--if BGB <cr88192@hotmail.com> - 2011-10-30 15:12 -0700
          Re: The difference between programmable and non-programmable logic--if Del Cecchi <delcecchi@gmail.com> - 2011-10-25 19:53 -0500
            Re: The difference between programmable and non-programmable logic--if Robert Myers <rbmyersusa@gmail.com> - 2011-10-25 21:29 -0400
              Re: The difference between programmable and non-programmable logic--if Quadibloc <jsavard@ecn.ab.ca> - 2011-10-26 08:57 -0700
                Re: The difference between programmable and non-programmable logic--if Robert Myers <rbmyersusa@gmail.com> - 2011-10-26 11:11 -0700
                Re: The difference between programmable and non-programmable logic--if Del Cecchi <delcecchi@gmail.com> - 2011-10-26 16:43 -0500
                Re: The difference between programmable and non-programmable logic--if jacko <jackokring@gmail.com> - 2011-10-26 14:45 -0700
            Re: The difference between programmable and non-programmable logic--if nmm1@cam.ac.uk - 2011-10-26 07:55 +0100
          Re: The difference between programmable and non-programmable logic--if MitchAlsup <MitchAlsup@aol.com> - 2011-10-26 18:03 -0700
            Re: The difference between programmable and non-programmable logic--if Stefan Monnier <monnier@iro.umontreal.ca> - 2011-10-26 21:43 -0400
  Re: The difference between programmable and non-programmable logic--if there is one. Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-10-23 23:28 +0200

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