sid123 wrote:but Unreal mode does cause problem for Cyrix Processors.
I found something that gets close, but it isn't actually unreal mode nor allowed according to the manuals. Therefore, citation needed.
If I remember correctly didn't he discover ModeX?
What Abrash is missing in hacking skills of the bigger pros he makes up in being able to write about it. Mode X is not his invention as far as I know, but he is the one who wrote the first known book on it. (If you read his work more, you'll see he credits ideas and help on several other people in his writing. John Carmack is one of the few actually mentioned by name, although I don't think he's the original source for Mode X either)
And I have no idea how many people individually invented unchained modes back in that day, because it's a bit of the logical consequence of experimenting with attempts to fix the memory issue in mode 13. I could say that I "invented" undocumented modes of my own as well, because I have no idea if someone else has had that same eureka moment somewhere else.