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Ask HN: How does code get translated to voltage inside a CPU transistor?

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Re: Ask HN: How does code get translated to voltage inside a CPU transistor?

#21

Post by matttheatheist »

roop wrote: post #19
matttheatheist wrote: post #14

Earlier quoted context omitted.

"At the physical level, the 1's and 0's are always voltage levels." Let me throw you a curve ball: When we're dealing with DIGITAL logic, we're dealing with DISCRETE (and finite) values of SOMETHING - and it doesn't have to always be voltages. Just to wet your appetite, take a look at "Current-mode circuits". These are circuits whose logic values are represented by discrete current levels, not voltage levels. And by…

You mean they don't always have to be "voltages". Agreed. I only wanted to emphasize that at the physical level, they are not discrete. In this case, they happen to be represented as voltage drops.

Agreed.

I wish more people would take the time to look at the classic CMOS inverter: Looking at the VIn vs. VOut graph, it is overwhelmingly obvious that the word "digital" refers only to a higher level of abstraction for circuits that, in reality, are analog. (And more to the point, these SAME circuits are used as amplifiers in a typical analog design.)

Good luck explaining this to a CS major.

Re: Ask HN: How does code get translated to voltage inside a CPU transistor?

#22

Post by hackaflocka »

T-hawk wrote: post #20

You're asking the question the wrong way around. Text doesn't get converted to 1's and 0's or turned into voltages. The 1's and 0's and voltages are the first principles. Code is emergent behavior. When you strike a key on your keyboard, what happens? A few circuit lines on the keyboard switch matrix that are normally open become closed circuits. These circuits are inputs to a keyboard decoder chip such as a 74C922.…

IMHO this is the most accessible and sensible ("makes most sense to me") answer so far. Thanks.

Re: Ask HN: How does code get translated to voltage inside a CPU transistor?

#23

Post by roop »

matttheatheist wrote: post #21
roop wrote: post #19

Earlier quoted context omitted.

You mean they don't always have to be "voltages". Agreed. I only wanted to emphasize that at the physical level, they are not discrete. In this case, they happen to be represented as voltage drops.

Agreed. I wish more people would take the time to look at the classic CMOS inverter: Looking at the VIn vs. VOut graph, it is overwhelmingly obvious that the word "digital" refers only to a higher level of abstraction for circuits that, in reality, are analog. (And more to the point, these SAME circuits are used as amplifiers in a typical analog design.) Good luck explaining this to a CS major.

That's funny. I am really a CS guy. Just happened to work for a semiconductor company for a few years after college.
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