https://www.intel.com/content/www/us/en/developer/articles/t...

Before the internet, Intel used to distribute these manuals in hard-copy for free. One just had to drop by your local Intel sales office to pick up a copy. A good solid foot of shelf-space.

These manuals used to be so much easier to read back in the 486/Pentium era. One could almost build a complete mental model of how a 486 worked, and how to manually optimize code to best effect by avoiding processor stalls.

Since then, intel processors have accumulated an extraordinary amount of cruft, so it becomes much harder to develop a complete mental model. Compilers have also gotten a lot more clever as well, in order to deal with the added complexity of SIMD instruction sets.

For those of us who started with the 8086 Architecture manuals, each generation of processors added additional features which one learned by occasionally revisiting the architecture manuals for new processors.

Coming to the Architecture manuals without having the foundation of previous Architecture manuals as a basis must be a daunting task. But I'm sure there's rich material there anyway.