Heh, I was putting the claim "unprecedented functionality" in doubt, in a historical context - nothing new about mounting ADFs, it (maybe) _started_ with fms, but moved on, and for the last decade it has been diskimage.device v53 that has been "the standard", open source and all - http://www.a500.org/main-menu/projects/diskimage-device.xhtml - and lastly, the GoADF! tool which now is in 3.0.
In this package, with the functionality in trackfile.device (which works almost exactly like trackdisk.device does, with the only command it does not implement being "TD_RAWWRITE") and the "user interface" of DAControl to go along with it, it's new. It's purpose made just to simulate floppy disk drives, which simplified the design, and also made it more complex because of what's emulated.
It was "interesting" to see how many quirks there are in the trackdisk.device API design and which surprises are lurking under the surface. For example, trackdisk.device supports CMD_STOP and CMD_START. To which end I cannot tell... When TD_REMOVE was "augmented" by TD_ADDCHANGEINT/TD_REMCHANGEINT the implementation did not keep the 'struct Interrupt' which TD_ADDCHANGEINT installs, but the entire 'struct IOStdReq'. You have to use the exact same 'struct IOStdReq' you added with TD_ADDCHANGEINT to shake it loose again with TD_REMCHANGEINT, and you must SendIO() to add and remove it. If you don't do that, there's going to be surprises along the way
Hence the need to build something from scratch which was much better suited to let you install the operating system from double-density Amiga-formatted disk image files which happen to reside on a "slow" storage medium (CD-ROM).
150kB/sec CD-ROM is considered slow? Luxury! Try disk images located on NFS shares mounted over serial port PPP links
This is pretty bad over classic Ethernet already
Well, I understand the need for this tool in the context of mounting disk images from the OS 3.2 CDROM fo the OS installer, but then again... the entire OS could just reside on the CDROM as files as well. Insidently, I don't even bother with CDROM drives these days, I just mount the iso9660 image directly, using - you guessed it - diskimage.device v53 - kinda daft to mount an iso9660 image just to mount ADFs from there again.
Images upon images will eventually lead to a stack overflow
All the disk wrangling (insert, remove) is done through a special command which talks directly to trackfile.device which avoids the need to use the Mount command and mount files.
I did not mention the Mount command, I mentioned the Mounter tool - there seems to be alot of overlap between Mounter and DAControl.
The approach is by necessity very similar. Even the mount information is practically identical with what the "strap" module uses to mount the Amiga floppy disk drives with.