 The limit on partition size was dictated by the 8-bit signed count of sectors per cluster, which originally had a maximum power-of-two value of 64.With the standard hard disk sector size of 512 bytes, this gives a maximum of 32 KiB cluster size, thereby fixing the "definitive" limit for the FAT16 partition size at 2 GiB for sector size 512.On magneto-optical media, which can have 1 or 2 KiB sectors instead of 0.5 KiB, this size limit is proportionally larger.