3.5" floppy disk drive. The drive has a 50pin ribbon cable connector on the back, marked "computer". The MSX interface is built into the drive, and is meant to connect directly with a ribbon cable to the "Expansion bus" on the back of certain Daewoo manufactured MSX computers.
Two variations are mentioned in the literature
The difference is that the C variant optionally supports CP/M, 17 tracks and a sector size of 256byte