I sort of like it when things I do get described as "magic", because I kind of agree, just not in the sense that it's usually meant.

Because usually it's things where they get to see the grand finish and are all "teach me your secrets". Then you try to do that and they somehow instantaneously lose interest once they learn that every single performance involves half an hour of tedious prep, two stage hands, and hundreds of hours of practice and rehearsal to be able to nail it in the first place.

"How do you know a bunch of obscure corners of x86 and ARM?"
I have, in the past, written both x86 assemblers and disassemblers, an ARM A64 assembler, several (small, specialized) compilers targeting both x86 and ARM, a very bare-bones x86 linker, and ended up, for professional reasons, reading almost all of:
- Intel's x86 manuals
- The ARMv8 ARM
- COFF and ELF specs (not DWARF though)
- The SysV ABIs for x86 and x86-64, and 64-bit ARM
- MS's Windows x64 ABI docs
mostly cover to cover.

Most of these things are not something I did for fun, it was something I was paid to do, and I did it.

I don't know any of those by heart, and I misremember a lot, but I have done it, and consequently there's a bunch of random crap I _do_ actually remember and for the stuff I don't remember, I at least have a vague recollection of where to find it.

All of this is public info. You can do the same. Incredibly dry reading though.

@rygorous For example - I cannot remember which register NUMBERS are assigned to ax, bx, cx and dx. All I remember is it's the third-to-last sequence you'd ever dream of.
@TomF why of course it's the most natural one: a c d b
@rygorous For those about to lose their hearing, we salute you.
@TomF @rygorous Thanks, now I'll never forget the order again.