The smallest, simplest, 'useful' (in terms of useful enough that lots of devs did good work with it and thus it might also be 'popular') ASM sets are probably also sufficient to start with. Provided you've got a good guide to using them, and also ideally a good sheet for why given instructions are packed the way they are in binary.

I do agree you're more likely to find pointers to such resources in more classic architectures. They're also more likely to be easy to find free copies of useful literature.

Here's the AMD manual: https://docs.amd.com/v/u/en-US/40332-PUB_4.08

Together, AX refers to bits [0-15]. EAX refers to [0-31].

It's counterintuitive (or at least, inconsistent) that we have a name for bits [8-15] but not for [16-31] or [32-63]. My fuzzy understanding is that this came about from legacy decisions.

This page has a helpful visualization at the top: https://www.cs.uaf.edu/2017/fall/cs301/lecture/09_11_registe...

>> Additionally, the higher 8 bits of ax, bx, cx and dx can be referred to as ah, bh, ch and dh.

* https://imada.sdu.dk/u/kslarsen/dm546/Material/IntelnATT.htm

* https://en.wikipedia.org/wiki/X86_assembly_language

Rather clunky and most UNIX Assemblers were never as powerfull as other systems macro assemblers, since after UNIX System V, it was there only as an additional external tool pass for the C compilation steps, and even before that, the assembler was quite minimalist.

Then there is the whole brain twist of being used to op dest, src, and having to switch into op src, dest.

I prefer the Intel approach as it is more similar to dest = src, rather than src -> dest.

Intel's approach is also more common across various assembly languages.