About msx Floppy Disk - Low level access?

SymbOS has its own implementation of disk access and supports different kinds of disk drives. I believe it can even do some auto detection to figure out what disk drive is present.

There are standard methods of accessing the sectors from the BDOS, so those games read the sectors and do not use the file-access interface of bdos.
Most likely they will have a custom made infrastructure that acts like a simplified filesystem.
A nice thing is that reading sectors is easy, while creating tracks is a whole lot harder, most diskprotection schemes use this to their advantage by creating disks with a non standard number of sectors/tracks etc etc that all systems can read but can (maybe) not create.

If you want to emaulte a floppy then you can opt to stay at the sector level(like most emulators do that use dsk files) or go really lowlevel and then you need to emulate a FDC at the level of the tracks and also implement the start of sector syncs etc etc.
In openMSX this is partially done in the emulation of the FDC to enable a correct _FORMAT working, without the need of patched or intercepted bios calls.

My idea is to make a cart with the less amount of electronic stuff as possible, an do the job on SW. I think about a cart that plugged on the msx on one side can be connected to a PC on the other. As soon as the z80 send data to the emulated port, the PC send back a response or data through the USB driver.
My question is about i/o ports. In order to make the emulated floppy device trasparent to the reall one i need to manage the same I/O addresses. However what happens if the cartridge is plugged on a real msx that has also the real floppy disk?

When the cpu addressed the floppy, both devices could reply... I think this could results in a short - circuit...
On the other hand, choosing another address will break the compatibility, forcing to write a new msxbios, or patching an existing one...
What solution? And which are the unused port addresses available?

@manuel:
there are differences:
-nowind, patch the bios (or rewrite it).
-nowind have built in memory.

Today, the floppy media is disappearing also from pc's.
Maybe tomorrow we cannot play on real msx because we do not have a true replacement for the msx floppy.
What i trying to create is a most-durable-solution to the 'floppy problem'.
My idea should be a cheap possible, no flash memory, only a virtual device emulated in SW on a PC.

What i need to know about is mainly:
1) In order to make the emulated floppy device trasparent to the reall one i need to manage the same I/O addresses. However what happens if the cartridge is plugged on a real msx that has also the real floppy disk?
2) choosing other addresses will break the compatibility, forcing to write a new msxbios, or patching an existing one... which are the unused port addresses available?

thx

That's quite standard.
Most software will just use the NoWind disk ROM as if it's a normal disk ROM.
the point is: are there sw that work skipping bios? If all msx sw uses bios there is no need to emulate the floppy.
This is not clear to me. Game like aleste load directly on disk and appear to manage directly the floppy HW. If this is true i think those games will not work until you emulate at a lower level (->HW) the floppy device.