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That the presence of voltage across a switch encodes 12 is purely arbitrary... Jeff Duntemann's book mentions:

We could as well have said that the lack of voltage indicates a binary 1 and vice versa (and computers have been built this way for obscure reasons)

I find this (italicized part) interesting. It would be great if someone could shed some light on what "obscure" reason(s) may motivate people to do so?

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  • $\begingroup$ I don't think there is any good reason, except for the fact that its more intuitive, and we can more easily represent numbers this way. $\endgroup$
    – nir shahar
    Jun 3 at 21:02
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    $\begingroup$ Also, this might be a better fit for the electrical engineering stack exchange $\endgroup$
    – nir shahar
    Jun 3 at 21:03
  • $\begingroup$ nir shahar, I'd like to see your reasons for that. And what evidence you have that any computer in your possession works that way. $\endgroup$
    – gnasher729
    Jun 4 at 7:02
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Quite opposite from what this Mr. Duntemann says, there are no "obscure" reasons for this at all. It is totally arbitrary whether you interpret "no voltage" as 0 or as 1. Anyway, you don't distinguish between "no voltage" and "voltage". You distinguish between "voltage below a low threshold" which is one binary value, "voltage below a high threshold" which is another binary value, "voltage between these thresholds" which is a state that should be avoided because things will not be reliable, and "exceedingly high voltage" which destroys your computer.

Look at your phone. Or your home computer. You have ABSOLUTELY NO IDEA if the processor inside interprets low or high voltage as 0 or 1. And you don't care. It doesn't make a difference. Of course the physical implementation of a NAND or NOR gate would be different.

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  • $\begingroup$ I get where you're coming from w,r.t thresholds and it being "purely arbitrary". There's after all no rational reason to assume I can't switch dots for dashes--and vice versa--in morse code, and call the unconventional--albeit equally-functional--resultant, puwlah code. But my q isn't that. It is this: if at all there's a convention (let's say to interpret below threshold as 0 and above threshold as 1), what possible purpose, however "obscure", could doing things the other way serve? Is there ANY seriousness behind this particular aside by the author, or is it maybe made to lighten the mood. $\endgroup$
    – puwlah
    Jun 4 at 8:17
  • $\begingroup$ There is no convention. It's purely arbitrary. If you go in slightly different areas - bits stored on an SSD drive, or data coming through your broadband connection. There are no single bits! $\endgroup$
    – gnasher729
    Jun 4 at 9:58
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    $\begingroup$ Consider this: If you interpret low/high voltages the opposite way, then a NAND gate becomes a NOR gate and vice versa. So you could check: With my interpretation, which is cheaper/faster/more reliable to build, a NAND or a NOR gate? And which do I need more of? $\endgroup$
    – gnasher729
    Jun 4 at 10:00

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