So much better written than Intel’s Software Developer Manuals, where anything complicated is just “look at these three pages of c-like pseudo code we probably pulled from our tests, good luck!”
IBM themselves have had to maintain backwards compatibility for > 50 years, and there is a long history of compatible machines: https://www.computerhistory.org/revolution/mainframe-compute...
So all the strange behaviours are well documented.
So much better written than Intel’s Software Developer Manuals, where anything complicated is just “look at these three pages of c-like pseudo code we probably pulled from our tests, good luck!”
IBM themselves have had to maintain backwards compatibility for > 50 years, and there is a long history of compatible machines: https://www.computerhistory.org/revolution/mainframe-compute...
So all the strange behaviours are well documented.