 As MS-DOS 3.0 and higher formatted all 16 MiB-32 MiB partitions in the FAT16 format, a 20 MiB hard disk formatted under MS-DOS 3.0 was not accessible by the older MS-DOS 2.0 although MS-DOS 2.0 was able to access 16 MiB-32 MiB FAT12 partitions.MS-DOS 3.0 to MS-DOS 3.30 could still access FAT12 partitions under 15 MiB but required all 16 MiB-32 MiB partitions to be FAT16, and so failed to access MS-DOS 2.0 partitions in this size range.MS-DOS 3.31 and higher could access 16 MiB-32 MiB FAT12 partitions again.