Comment by hedgehog
1 day ago
An accurate emulator with clean codebase is a good starting point onto which to add patches/shortcuts. I've looked through the Basilisk patching code, it's not really complicated, and there are a handful of partial Toolbox reimplementations including the bits in Basilisk, Executor (author is in the comments here), MACE, etc. It would be some work to port but mostly direct translation of the code & adding test infrastructure.
As an aside, I really wish MACE would open-source their work. They've made some impressive progress, but I worry that work's going to go to waste if it stays closed.
Aha, I got MACE and Advanced Mac Substitute (AMS) mixed up. AMS looks less complete but has source available.
https://www.v68k.org/advanced-mac-substitute/
One way to add devices that doesn't require ROM or software modification, but _does_ require modifying the emulator: create a virtual memory-mapped device off 68K bus, and write a driver/CDEV to drive it. The SE and Macintosh II had blessed but different expansion options, after all.
For earlier models, there are unused apertures in model memory maps that are at least 2KB large, but they do differ between models.