Most people called it unreal mode.

https://en.wikipedia.org/wiki/Unreal_mode

Shameless plug for my https://blogsystem5.substack.com/p/beyond-the-1-mb-barrier-i... article from a couple of years ago. You'll find a deep dive on unreal mode (I just learned it's also known as "vodoo mode") and some hands-on code to play with it ;-P