This document discusses disk operating systems and file systems. It defines a file as a named collection of related information stored on secondary storage. Files have attributes like name, size, type and location. The document describes file operations like creating, reading and deleting files. It explains different file types and structures. The document also discusses file allocation tables (FAT) which are used by operating systems to manage files and clusters on storage drives. It provides details on physical structures of floppy disks and hard disks, including system and data areas.

1. DISK OPERATING SYSTEM
Mrs Vimal Madhale Mhetri
Lecturer MSN

3. File
Directories

4.  A file is a named collection of related information
that is recorded on secondary storage.
 The operating systems maps this logical storage
unit to the physical view of information storage.
 A file may have the following characteristics
 File Attributes
 File Operations
 File Types
 File Structures
 Internal Files
FILES

5. 1. File Name: The symbolic name is perhaps the only
human readable file attribute.
2. Identifier: A unique number assigned to each file for
identification purpose.
3. File Type: Some systems recognize various file
types Windows is a good example.
4. File Location: A pointer to a device to find a file.
5. File Size: The current size of a file, or the
maximum allowed size.
6. File Protection: This is for access-control.
7. File Date, Time, Owner, etc.
FILE ATTRIBUTES

6. 1. Creating a file
2. Writing a file
3. Reading a file
4. Repositioning within a file
5. Deleting a file
6. Other operations (e.g., appending a file, renaming a
file)
File Operations

7. 1. Primary Name
2. Extension Name
FILE TYPES

8. 1. An operating system becomes more complex
when more file types (i.e., file structures) are
supported.
2. In general, the number of supported file types is
kept to minimum.
File Structure

9. Access method: how a file be used.
There are three popular ones:
Sequential access method for sequential
files
Direct access method for direct files
Indexed access method for indexed files.
File Access Methods

10. 1. Primary file included with 1 to 8 letter.
2. There should not be space in-between the
file name.
3. Include the word from letter {AtoZ}, [0-9] , ~
! $ ^ & () – _ {} but not – [] / < > .
4. Primary Name and Extension Name should
be included . (DOT) in-between
5. There should not be space before and after .
DOT
RULES OF FILE NAMING IN DOS

11. What is FAT, Characteristic of
FAT

12.  A file allocation table (FAT) is a file system developed
for hard drives that originally used 12 or 16 bits for
each cluster entry into the file allocation table. It is
used by the operating system (OS) to manage files on
hard drives and other computer systems.
Definition file allocation table (FAT)

13.  First time it used in 1980 by Tim paterson in 86-Dos
for Eg: FAT12,FAT16, FAT32,etc
 To keep file properly in operating system FAT file
system Is used it Is named as cluster.
 There are different file system are available in market
like FAT, NTFS, DOS, FAT .
 FAT - File Allocation Table is used to keep file in Hard
Disk to store in that.
Characteristic of FAT

14.  FAT File divide the hard Disk termed as Cluster.
 Cluster is made up of 1 or more sectors.
 1 Cluster = 1 to 128 sectors
 Each Cluster saved with unique serial Number, which
will be recorded in file allocation Table.
 0 – Empty or free disk.
 Serial Number – Occupied Disk

18. DOS PROMPT AND DRIVE
NAME

20.  Soon after Start of computer DOS is RAM will
Start.
 And on computer Screen will be checked with
command
 A:/>
 C:/>
 If any we want to write it will Start after this
command only.

21.  If we are working on Floppy Disk than A:/>
 will be seen on Computer screen. Than we can
write any thing we want to write.
 If we are working on Hard Disk than C:/>
 Like this DOS prompt how it ready to work
and also gives information regarding Drive,
Directories.
 If hard disk Is having more than 2 partition
than drive name goes on like C, D, E etc

22. PHYSICAL STRUCTURE OF FLOPPY
DISK AND HARD DISK

24.  In Computer Hard Disk and Floppy Disk used as a
External Memory. which Is made up of Magnetic
Material and also it Is a Fixed Disk , in system.
 Floppy Disk, Is Portable Disk : which can be removed
and inserted in another computer.

25.  Floppy disk two types and shape
1. Mini Floppy
2. Micro Floppy

27.  To keep the data in arranged and safe DOS memory
Disk Is divided in to two types:
1. System Area
2. Data Area
Physical Structure of Disk

28.  This share too small portion of the Disk that Is only
2%. which Is responsible to save the soft copy of
principal file which will not be changed.
 System Area’s DOS Is divided in to 3 parts
 Boot Records
 FAT
 Root Directory
1. System Area

29.  It I also called a partition sector or Boot sector which
will be having capacity of 512 bite area, in first sector
Is Head sector and remaining all sector are used for
overall information.
 It Is used to keep Disk primary partition table.
 To keep the User I D and Pass word in safe.
 To recognise the Disk which Is made up of 32 bite.
 It Is used to keep memory space in record.|
A. Boot Records

30.  (File Allocation Table) FAT : It I very important
because it keep record regarding data area which file
has been kept in which area.

B. FAT

31.  It come under file system.
C. Root Directory
Root
Directory

32. It I about 98% of Disk space Is
occupied by this data area which I included with
small small cluster and cluster included with
different number and with different data in
that.
2. Data Area