I understand the concept of transistors and electricity flipping them to an on/off state. What I do not understand is how these transistors work. Do they physically move? How is it decided where the electricity goes? I do not understand how the power is controlled, and how it is decided what transistors activate and when
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The very very simple version is that through several layers of abstraction, the decision of what transistors activate when is decided by your input devices and by your software.
The less simple version is that we use an abstraction called *opcodes* to dictate what a processor does – the way this typically works is that you take a string of 8, 16, 32, or 64 bits and look at specific subsets of values in those bits to mean certain things.
As a completely arbitrary example that probably doesn’t map to any real world process, we might decide that our processor will take 8 bit inputs, and that we will split them up into a pair and two triplets, as such:
00 000 000
And so we might decide that the first pair dictates what mode we are in:
* 00 = immediate mode – send the other 6 bits directly into memory address 0
* 01 = addition mode – add the data value in the memory address specified in the first triplet to the data value in the memory address in the second triplet, and store the value in a predetermined memory address.
* 10 = logic mode – run the data from the memory register in the second triplet through binary logic gates determined by the first triplet
* 11 = unused, for future operations.
This is, again, highly simplified, in real life we would have an entire 8 bits or more dedicated to your opcode, and memory addresses that were 64 bits long. That is a very very simple processor that can do addition and data storage and not much else at the moment.
But for all other operations it is the same – that abstraction is how we describe what wires are being turned on to activate what transistors in what order.
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