Comment by bogomipz | Hacker News Reader

Comment by bogomipz | Hacker News Reader

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I have a question about the relationship between the "simplified transistor" animated gif and the "Simplified AND and OR gates, using transistors" animated gif here:

https://cdn.arstechnica.net/wp-content/uploads/2022/09/and-o...

The image in the URL above represents two transistors in each gate type, where the transistor is shows as a circle with 3 rectangles in it. Is my understanding of this relationship correct if I assume the following?

The line labeled "input" in the animated gif maps to the gate in the transistor.

The line labeled "output" in the animated gif maps to the drain in the transistor.

The line labeled "voltage" in the animated gif maps to the to source in the transistor.

In other words gate equates to input, the output equates to drain and voltage equates to source and the distinction between these is really whether we are talking about the transistor or a circuit(gate) made up of those transistors?

You've got it right. I was going to label the inputs in the transistors in the second animation, but it made the diagram rather crowded, so I left it out.

The diagrams are simplified because they leave out things like connections to ground, attached resistors that mitigate the total current, etc. But I wanted to convey, as simply as possible, how transistors worked and how gates could be made very simply out of a small number of transistors.

The actual CMOS chips in use by ARM (and still in use today) complicate things more, because you have different types of silicon (NMOS and PMOS) on the same substrate, so the transistors work slightly differently and you can simplify making things like NAND gates, which themselves can be combined to make all other types of gates. For this article, I didn't want to get that deep into the woods, though. :)

Hi, thanks for the article, I'm looking forward to the next installment! I hope you post it here when it comes out.

I actually appreciated the simplicity of the diagrams and I think most literature follows this where terminals(I think that's the correct term) are marked source, gate and drain and then the circuits are denoted input, output, voltage/vss. I've never seen it stated bluntly that "gates mean this in this context and we refer to as an input in the circuit context." Maybe it's just considered too obvious but it's always made me question my own understanding. Thanks for the confirmation.

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