Voici quelques réponses que j'ai pu lire à ce sujet :
ok. It is theoretically possible to convert some of the cprs back to dsks (as long as they are made with nocart and have not had plus features patched into them) but no tool currently exists to do that.
The problem you would have is launching the disks, cprs are autoboot because of their nature, but dsks are not. So you would need to run the dsk in the same way as you would any other dsk.
It may be possible with some, but each would have to be done on a case by case basis, and would probably need 128KB or have pauses for loading during play.
On c64, a lot of the carts were treated as mass read-only storage, reading data into ram quickly. On Plus, you can page bits of the rom in and out, so it's more like a big rom expansion. So depending on how the cart is used, it may be possible to move some into ram and patch the code to use it.
Ohh, this is a real chalenge. Run any of the original GX games from disc. Many changes have to be made. And each game can be a unique case.
There are great devices like C4CPC but I think the M4 can be used also...
I was able to override the cart at boot time by using the lowfirmware option and the priority of M4 roms over internal ones (from the cart)
My theory is that if you setup the romboard start at 128 and replace the first 8 roms wirh the 8 blocks from the cart, and mirror the first block to slot 31 (for lowfirmware replace) you will have the cart run from M4 and use the cart ACID protection chip.
I will try to get some time for testing.
But the native CPR to DSK, is a pretty hacking exercise. Those games are designed to run and load data from ROM. You have to intercept any rom access and turn into AMSDOS loading from files. Maybe you have no free memory for AMSDOS...