If there are billions of transistors in a CPU, there is no chance that somebody designed every single one of them manually. Is their layout calculated or something?
In: 1270
Transistors are just switches, I’m sure you know this, and switches just perform logical operations when combined in certain way.
Once you know what the small number of individual components can do to a bit of a data, you can use abstract design principles to layout more and more complex structures. You can literally write a simulation of a processor in many computer languages, because at the heart of a processor microchip, you’re just manipulating data in much the same way that you do with any other program that runs ON the processor.
Now if we are talking about the FIRST powerful processors, they very much were designed by engineers and scientists by hand, drawn out, broken down into distinct regions of the processor, and worked on and tested etc. The great thing about this process is that once you find one way that works, it will always work – it just might become outdated if they find a better way to do it. If you design one successful microprocessor you’ve just completed not a stair step, but an elevator that can assist your future designs and make them ten times easier to complete. It’s an exponential progression because of how powerful microprocessors can be.
Modern chips are designed by scientists and engineers, but mostly through a lot of theoretical research and small scale testing to see if it is possible to adapt small, but meaningful, new ideas to the development of the next generation of processors. Each new processor in a line of products isn’t usually a discreet product, it’s actually more likely to be the same exact design that did not hold up to benchmarking standards and is then marketed as a slower or less powerful processor. This is not always the case, but it’s common.
There is no good ELi5 answer to this question, because every small step of designing and creating a microprocessor itself is a huge topic that there are literally books written about, and people take years of schooling to understand, from optical lithography, chemical etching and vapor deposition, just the simple topic of understanding how electrons flow through a transistor require a very real understanding of quantum mechanics, and in fact we are nearing the limit of how small we can make a transistor before our electrons start disappearing and reappearing in places they aren’t supposed to due to the “quantum tunneling” effect of subatomic particles.
It’s a vast topic, one better left to baby steps upward toward a career in the field or at least a high level discussion with an expert via youtube or Ask Science on reddit, this one is definitely not best suited for an ELi5. That being said, I hope my answer and many others helped you get a small grasp on the topic and understand how the incredible advancement in microprocessor technology has advanced further in the last 50-60 years than arguably any other human scientific endeavor in the history of the world.
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