I’ve been curious about some details of how the Apple II emulation disk for the Apple III works, so I’ve been working on reverse-engineering the code. I’ve just put it up on github.
The first 1 1/2 tracks of the disk get loaded into memory from A000..B7FF. That loads the Apple II ROM images into memory from 2000 up. Then it gives the user a chance to change some configuration options. Finally it copies the ROM images into place, does some more hardware configuration, sets the hardware Apple II emulation mode, and jumps into the Apple II monitor ROM.