Comment by lispm
probably there were no such machine-level instructions, but assembler macros
probably there were no such machine-level instructions, but assembler macros
The page doesn't say that these were predefined assembler macros provided by IBM. I'm tending toward the interpretation that the Lisp guys themselves (likely Russel) wrote these macros as part of the assembly language implementation of the interpreter. Which means they specified them to the assembler, rather than the other way around.
I felt it simplified the description to not mention they were assembler macros, but in retrospect, that was begging for a correction :-)
The linked page with details was interesting, thanks!