1 Floppy Drive Formatting ©Richard Goldman February, 2001

2 The First Step Low Level Format (LLF) Tracks are placed on the disk. Tracks are divided into sectors.

3 The First Step Low Level Format (LLF) Prefixes are added to each sector – Including: Sector I.D. Cylinder Number Head Number Sector Number Sector ID CRC (Cyclic Redundancy Checking ) Gaps

4 The First Step Low Level Format (LLF) Suffixes are added to each sector – Including: Buffer area and Gaps Data CRC The data areas are filled with F6h (  )

5 Low Level Format Tracks are placed on the disk Track

6 Low Level Format Tracks are divided into sectors Sectors

7 Low Level Format Prefixes are added to each sector Prefix - Including: Sector I.D. Cylinder Number Head Number Sector Number Sector ID CRC Gaps

8 Low Level Format Suffixes are added to each sector Suffix – Including: Buffer area Data CRC Gaps

9 Low Level Format The data areas are filled with  ’s Data Area Note: ASCII Character -  Binary – Hexadecimal – F6h Decimal – 264

10 The Second Step Master Boot Record (MBR) The first sector of the disk is used to store the MBR. Cylinder 0 Head 0 Sector 1

11 Master Boot Record MBR

MB Floppy Master Boot Record Information Bytes per Sector Sectors per Cluster Number of FAT’s Size of the Root Directory Number of Sectors Medium Descriptor byte Size of FAT Sectors per Track Number of Heads Number of Hidden Sectors Program to Load OS

13 Bytes per Sector 512 bytes

14 Sectors per Cluster 1 Sector

15 Number of FAT’s 2 FAT’s

16 Size of the Root Directory 7808 Bytes (224 Records X 32 Bytes/Record)

17 Number of Sectors 2880 Sectors (18 Sectors X 80 Tracks X 2 Heads)

18 Medium Descriptor byte Type of material used to make disk.

19 Size of FAT Uses FAT12 Uses 12 Binary digit number to identify each cluster. Example: = first cluster

20 Sectors per Track 18 Sectors

21 Number of Heads 2 Heads

22 Number of Hidden Sectors Includes the number of sectors used by the MBR, Root Directory, and the two FATs.

23 Program to Load OS A program that attempts to load the operating system. If IO.SYS in not found on the disk a “ Non-system disk error ” is given.

24 The Third Step File Allocation Table (FAT) Two FATs are created in the space immediately following the MBR.

25 File Allocation Tables MBR FAT 1 FAT 2

26 File Allocation Table The FAT is a table of all the sectors available for use on the disk. The FAT has one column of information: A sequential list of all the data clusters on the disk. (The sectors used for the MBR, FATs, and Root directory are not included.) FAT 12 is used on floppy disks. This means each cluster is identified with a 12 bit binary number in the FAT.

FFF FFF FF7 008FF A FFF 00BA2E Cluster Number FAT Information Continues Each entry points to the next cluster in chain of clusters that make up a file. The last cluster in the chain is marked with FFFh ( ) Known bad clusters are marked with FF7h ( )

28 The Fourth Step Root Directory The Root Directory is created in the space immediately following the second FAT.

29 Root Directory MBR FAT 1 Root Directory FAT 2

30 Root Directory The Root Directory is a table that contains a list of all files and subdirectories in the “Root” or first directory on the disk. A 3 ½ inch High Density (HD) floppy disk can hold a maximum of 224 entries.

31 Contents Root Directory File Name File Extension Attribute – R, A, S, H, File/Subdirectory, Volume Label Time – Created/Updated Date – Created/Updated Starting Cluster File Size

32 Maximum Number of Root Directory Entries DriveFile SystemMax Entries 3.5” Floppy - HDFAT12224 Hard DriveFAT16512 Hard DriveFAT32Unlimited Hard DriveNTFSUnlimited The use of LFNs can reduce the number of entries.

33 Deleting a File The first letter of the file name is replaced with the lower case Greek letter sigma (  ) in the Directory. The FAT entry is replaces with 000. The data on the disk is NOT deleted. The data will remain on the disk until it is overwritten by another write process. It may be possible recover “Deleted” data with undelete utilities.