As the author of https://superuser.com/a/347115/38062 and https://superuser.com/a/345333/38062, you have my sympathy about the "pack of lies" involving real mode and several wrong combinations of selector and offset.
Four particular ones come to mind:
* The DPT range of SCSI host bus adapter cards, many years ago, had an full blown MC680x0 processor on the card.
* Connor Krukosky, who famously installed a mainframe in his basement with a console front-end processor that was a PC machine running OS/2.
* PC/AT keyboards had on-board microcontrollers running programs.
* And of course who can forget the BBC Micro's Tube?
It's the short period in history where people thought that computers came with only one processor that is the real oddity. (-:
The elegant and well adhered to OS calls made this a straightforward process, if your program ran on the BBC standalone it would work across the Tube for the 65(C)02, but for other coprocessors you had to at a minimum recompile and probably rewrite quite a bit of your code.
https://sites.google.com/site/jamesskingdom/Home/computers-e...
In a typical PC there are > 10 actual processors in the various peripheral and controller chips, and then there is the management engine (a full blown computer in its own right) or equivalent and usually almost every peripheral will have one or more processors as well.
Moreover Intel is just this week actually finally proposing removing real mode. [2] I'm a bit worried for what this means for emulation of old 16-bit Windows and DOS software under Wine (one of the great ironies that Wine can still run Win16 programs on an x64 host OS when Windows can't) - though I suspect the performance requirements of such software is so low by modern standards that emulating such programs wouldn't pose any challenge.
[1] https://www.devever.net/~hl/ortega [2] https://www.phoronix.com/news/Intel-X86-S-64-bit-Only