Yes, only four partitions is a limitation with the actual FAT12 situation.
No, it is limit of standard MBR. And the solution are the Extended partitions, which is use only one entry in the MBR table.
Then the limits only the available drive letters
Under the EXDOS F-Z are available.
My IDE/SD driver collect details of all FAT partitions (LBA start, size, type) at system start, later no partition tables used.
The question are: how many drives (letters) are possible under SymbOS? If also possible up to Z, then only the partition collection routine needed to be extended.
There is also a "not partitioned" option, probably to format to FAT16/32 within SymbOS.
SD cards can be exist without partitions, 0. logical sector store the boot sector like as the floppy.
Now that IDE disks can coexist with the SD-reader, you must describe the device to Prodatron to be included on the list of devices.
Some power users want it!
Also, in the future, explore how to return to EXOS without losing its integrity. Also, a way to launch an EXOS app.
For this need to be system segment don't overwrited. Prodatron say previously it is only possible in the "for extended Enterprise" version, which can be use a different memory map.