CrossDOS was a combination of mfm.device (asking the disk hardware to do funky things) as well as CrossDOSFileSystem (FAT12 filesystem handler).

What's interesting is not so much the 68K emulator (though that is interesting for Python), but rather that it's using VAMOS - the most amazing thing about the amitools project.

VAMOS is a full-on pretend version of AmigaOS in Python, that hooks everything up so that e.g. dos.library's Open() actually calls Python's open(), and so on.

https://github.com/cnvogelg/amitools

Here is, for example, its fake implementation of dos.library: https://github.com/cnvogelg/amitools/blob/main/amitools/vamo...

The "libcore" code reads a .fd file (which on the Amiga is a parseable description of the API calls in a library, for generating include files and stubs), then it creates a fake library base in memory with fake jumptable entries... which jump to two instructions, an "ALINE" trap (any two bytes from 0xA000 to 0xAFFF, which trigger the 68000's ALINE trap handler, one is allocated for each library call), then RTS... That's enough to let Python take back control from the emulator when the trap arrives, and emulate the API call.

It does make me wonder how scalable VAMOS if there are no more than 4096 library calls possible.

Anyway, what concerns me about amifuse is that VAMOS has no BCPL internals. pr_GlobVec isn't filled out. AmigaDOS 1.x was written in BCPL (it's an Amiga port of TRIPOS), and AmigaDOS 2.x/3.x went to great pains to pretend BCPL internals were still there, even though they weren't. I'm sure I've seen a number of filesystem handlers that relied on BCPL internals... these just won't work in VAMOS as it stands, and therefore won't work in amifuse.

It's a little bit odd that amifuse only demonstrates working with PFS. Does it work with AFS (AmiFileSafe), SFS (SmartFileSystem)? What about FastFileSystem, CacheCDFS, CrossDOSFileSystem, MultiUserFS and so on?

For that matter, the native filesystem handler in AmigaOS 2.x/3.x was ROM resident. How would one extract it and patch it up to run outside the ROM, so that it could then be use with amifuse?