 The PC XT was the first PC with a hard drive from IBM, and PC DOS 2.0 supported that hard drive with FAT12 (FAT ID 0xF8).The fixed assumption of 8 sectors per clusters on hard disks practically limited the maximum partition size to 16 MiB for 512 byte sectors and 4 KiB clusters.The "BIOS Parameter Block" ("BPB") was introduced with PC DOS 2.0 as well, and this version also added read-only, archive, volume label, and directory attribute bits for hierarchical sub-directories.