I'll fill in some more things. They didn't have the bloat back then that we have these days, like the crazy deep call stacks you see in both object-oriented and functional programming. CICS programs were frequently written in assembler, sometimes COBOL and PL/I. Mainframe compilers from the early 1970s were much more advanced in many ways than the Unix/C technology described in the Dragon Book. The mainframe did I/O…
Thanks for elaborating more. I think people who do performance work constantly rediscover or re-invent this (ie like the websocket post).