The description of all MGT filesystems is at the website of Wikia. SAMDOS springs from GDOS/G+DOS. Better choice of the minimalistisc DOS for the SAM Coupé is QDOS.
MasterDOS, improved SAMDOS, brings comfort, speed, ramdisks, variable directory length (up to 778 files on the disk, FORMAT "d1",39) and subdirectories.
BDOS provides an access to the SAM/Disciple/PlusD disk images stored on harddisks, CF and SD cards and data CDs. Directly from BASIC are supported audio CDs and CD/DVD directories, but not writing into the PC/Windows FAT structure. By the use of BASIC commands could be driven: idle mode, auto power down counter, stand-by mode, sleep mode, CD/DVD drive: control drive tray, medium removal, playing audio tracks - pause, resume, stop.
The most versions of DOS could read GDOS/G+DOS (BetaDOS and UNIDOS?) formats and partly work with the ZX files (copy, rename, load code and screen$). The full support to the Disciple/PlusD disks on the SAM is built in Speccy emulators with modified roms.
For the Speccy is the +divide system available (GDOS/G+DOS modified for the divIDE).