Sample Chapters from book DATA RECOVERY WITH AND WITHOUT PROGRAMMING by Author Tarun Tyagi

Table of Contents

PREFACE

Chapter-1 An Overview of Data Recovery

• Introduction to Data Recovery
• Understanding Data loss
  • System Crash
    • Human Error
    • Software Corruption
    • Software Malfunction
    • Hardware Error
    • Virus Crash
    • Sabotage
    • Natural Disaster
  • Other types of data loss
    • Loss of one or more partitions
    • Floppy Read Error
    • Deletion of important data
    • Password loss
• Types and areas of Data Recovery
  • Analyzing a computer before Data Recovery
  • Acceptable recovery period
  • Understanding various costs
    • Downtime Costs
    • Data Recovery Costs
  • User description
  • Defining the requirements
  • Making objectives
• Some Advices before beginning the Disk troubleshooting or Data Recovery procedure
  • Some tips to Protect your Data
  • Make the Backups
    • Perform surface scanning monthly
    • De-fragment of data weekly
    • Use good antivirus program
    • Get into the habit of keeping your floppy write-protected
    • Do not use pirated games and software

Chapter-2 Introduction of Hard Disks

• Introduction
• Components of hard disk
  • Disk Platters and Media
    • Read/Write Heads
      • Head Crash
      • Head Parking
    • Head Sliders, Arms and Actuator
      • Head Sliders
      • Head Arms
      • Head Actuator
    • Spindle Motor
    • Connectors and Jumpers
    • Logic Board
    • Cache and Cache Circuitry
• Low-level hard disk geometry
• Formatting
  • Low-Level Formatting
    • Partitioning
    • High-Level Formatting
• Formatted and Unformatted Storage Capacity

Chapter-3 Logical Approach to Disks and OS

• BIOS
  • The INT 13H Interface and INT 13H Extensions
    • Int13H Extensions
    • The 2.1 GB limit
    • The 33.8 GB limit
    • ATA Specification for IDE Disks - The 137 GB limit
  • Two and Four Disk BIOS IDE Support
• Limitations in File Systems
  • FAT12
  • FAT16
  • FAT32
  • NTFS
• Cluster
• Cluster Size
• Logical Structure of a Hard Disk
• Master Boot Record (MBR) or Master Partition Table (MPT)
• Master Boot Record Format
  • Partition Table Entry Format
    • Boot Type Indicator Byte
    • Starting Cylinder-Head-Sector Number of the Partition
    • File System Indicator Byte
    • Ending Cylinder-Head-Sector Number of the Partition
    • Relative Sector number of Beginning of the Partition
    • Number of Sectors of the Partition
  • DOS Boot Record (DBR) / DOS Boot Sector
    • Number of Root Directories
    • Total number of Sectors
    • Media Descriptor
    • Number of Sectors of FAT
    • Sectors Per Track (or Sectors Per Head)
    • Hidden Sectors
  • File Allocation Table (FAT)
    • How Windows detects the Improper - Shutdown
  • Root Directory
  • Long File Name (LFN)
  • Data Area (or Files Area)
  • Fragmented and Defragmented Data
  • Identifying the cause of data corruption
    • Boot the system with bootable floppy
      • Verify the MBR Information
      • If MBR is okay, Verify DBR

Chapter-4 Number Systems

• Introduction
• Decimal Number System
• Binary Number System
  • Binary to Decimal number Conversion
  • Decimal to Binary number Conversion
  • Binary Number Formats
    • The Bit
    • The Nibble
    • The Byte
    • The Word
    • The Double Word
• Octal Number System
  • Binary to Octal Conversion
  • Octal to Binary Conversion
  • Octal to Decimal Conversion
  • Decimal to Octal Conversion
• Hexadecimal Number System
  • Binary to Hexadecimal Conversion
  • Hexadecimal to Binary Conversion
  • Hexadecimal to Decimal Conversion
  • Decimal to Hexadecimal Conversion
• ASCII Code
• Some important number system terms, often used for Data and Data Storage representation
  • Byte
  • Kilobyte
  • Megabyte
  • Gigabyte
  • Terabyte
  • Petabyte
  • Exabyte
  • Zettabyte
  • Yottabyte
• Common Data Storage Terms

Chapter-5 Introduction of C Programming

• Introduction
• Why use C in Data Recovery Programming
• Let me assume that you know nothing in C
• Let us start
• Keywords
• Compiling the program
• Printing Numbers
• Using Variables
• Numeric Variable Types
  • Initializing Numeric Variables
• Operators
  • Assignment Operator
  • Mathematical Operators
  • Relational Operators
  • Logical Operators
  • The Comma Operator
• Something more about printf() and Scanf()
• Control Statements
  • The if else Statement
  • The switch Statement
  • The break Statement
  • The continue Statement
• Loops
  • The while Loop
  • The do while Loop
  • The for Loop
  • The goto Statement
• Pointers
• Array
  • Character Arrays
  • Accessing the Elements
  • Initializing Array Elements
  • Looping through an Array
  • Multidimensional Arrays
• Strings
  • Some Common String Functions
  • The strlen Function
  • The strcpy Function
  • The strcmp Function
  • The strcat Function
  • The strtok Function
• Functions
  • Pass By Value Functions
  • Call-by-reference
  • Dereferencing
• Memory Allocation in C
  • Reallocating Memory
  • Releasing Memory
• Structures
  • Structures with Pointer Members in C
  • Structure Initialisers in C
  • Passing Structures to Functions in C
• Union
  • The union Keyword
  • A practical use of a union in data recovery
• File Handling in C
  • The File Modes of fopen Function
  • Closing Files
  • Reading Files
  • Writing to Files
• Command Line Arguments with C
• Bitwise Manipulators
  • Bitwise AND
  • Bitwise OR
  • Bitwise Exclusive OR
  • Bitwise Compliment
  • Bitwise Shift Left
  • Bitwise Shift Right
• Functions to Binary–Decimal and Conversions
• Function for Decimal to Binary conversion
• Function for Binary to Decimal conversion
• Debugging and Testing
  • Syntax Errors
  • Logic Errors
• Testing
  • Some testing principles
  • White Box Testing
  • Black Box Testing
  • Equivalence Classes
  • Boundary Value Analysis
  • Devising a Test Plan

Chapter-6 Introduction to Computer Basics

• Introduction
• Basic concepts
  • Central Processor
    • Central Memory
    • CPU Registers
    • Assembler structure
    • Advantages of the Assembler
    • Let me keep my promise
    • Storing and loading the programs
    • Segments
    • Data movement
  • Interruptions
    • Internal Hardware Interruptions
    • External Hardware Interruptions
    • Software Interruptions
• Int 20H, Terminate process
• Int 21H, MS-DOS System functions

Chapter-7 Necessary DOS Commands

• Introduction
• Brief History
  • Microsoft Disk Operating System
  • (MS-DOS) Version 1.0
  • MS-DOS Version 2.0
  • MS-DOS Version 3.0 to 5.0
  • MS-DOS Version 6.0
  • MS-DOS Version 7.0 (Windows 95)
• Necessary commands
  • ATTRIB
  • CD (or CHDIR)
  • CHKDSK
  • CLS
  • COMMAND
  • COPY
  • DEBUG
  • COM Extension
  • EXE Extension
  • DEL (or ERASE)
  • DELTREE
  • DOSKEY
  • DIR
  • DISKCOPY
  • EDIT
  • EXIT
  • FC
  • FDISK
  • FIND
  • FORMAT
  • LABEL
  • MD (or MKDIR)
  • MORE
  • MOVE
  • RD (or RMDIR)
  • SCANDISK
  • TYPE
  • XCOPY
• Specification shortcuts, Wildcards and Redirection
  • Shortcuts
  • Wildcards
  • Redirection
    • >
    • >>
    • <
    • |

Chapter-8 Disk-BIOS Functions and Interrupts Handling With C

• Introduction
• biosdisk and _bios_disk Functions
• diskinfo_t Structure
• absread and abswrite Functions
• Interrupt Handling with C
  • SREGS Structure
    • REGS Union
    • BYTEREGS and WORDREGS Structures
    • int86 and int86x Functions
    • segread Function
    • intdos and intdosx Functions
• How to know the Physical Hard Drive Number
• Interrupt 13H (INT 13H), ROM BIOS Disk Driver Functions

Chapter-9 Handling Large Hard Disks

• First of all, let me tell you a Story
• INT 13H Extensions
• How to use INT 13H Extensions in C Programming
  • Comments on Coding of the program

Chapter-10 Data Recovery From Corrupted Floppy

• Why the floppy is not readable
  • How to recover
  • Method – 1
  • Store the boot image of any fresh floppy
    • Making the image of DOS Boot Record of a good floppy
      • Comments on Program coding
    • Pasting the boot image to the first sector of Unreadable floppy
      • Comments on Program coding
    • Let us do it with single program
  • Comments on Program coding
  • Storing the boot Image in HEXADECIMAL Characters to use in our previous Program
  • Comments on coding of the program
  • Method – 2
    • What to do if Method-1 doesn't work
    • Copy all the data of media surface to a single file
      • Comments on Program coding
    • Thinking for the solution of sector(s) reading error
      • Comments on Program coding
    • Paste the Data from the file to the physical surface of fresh floppy
      • Comments on Program coding
    • Thinking for Logical Recovery for Deleted or lost Data
      • Comments on coding
      • Comments on coding
      • Comments on coding

Chapter-11 Making Backups

• Why Backups
• When and what to Back up
• Backup of MBR (Master Boot Record) and its use
  • Why Backup MBR
  • What Can Be Recovered with the Backup of MBR
  • Writing the Program to make Backup of MBR
    • Comments on Program coding
  • Program to Restore the MBR from Backup
    • Comments on Program coding
• Backup of DBR (DOS Boot Record) and its use
  • Why Backup DBR
  • What can be recovered with the Backup of DBR?
  • Programs for Making and Restoring Backups of DBR
• Complete Disk Imaging
  • Writing the program for complete disk imaging
    • Comments on Coding
    • Comments on Coding

Chapter-12 Reading and Modifying MBR with Programming

• Master Boot Record (MBR) or Master Partition Table (MPT)
• Master boot record format
• Partition Table Entry Format
• Writing program to read the partition table of MBR
  • Comments on coding
• Program to find all logical partitions and their information
  • Comments on coding
  • Comments on coding
• Modify MBR by Programming
  • Comments on coding

Chapter-13 Reading and Modifying DBR with Programming

• DOS Boot Record (DBR) / DOS Boot Sector
• Reading DBR of Floppy and Small Volumes
• Reading the DBR of Large Volumes
• How to Recover DBR with Programming
  • Comments on coding

Chapter-14 Programming for "Raw File" Recovery

• Raw File Recovery
• Headers and footers of some important file types
• Writing a program for Raw File Recovery
  • Comments on coding
• INT 10H, function 01H - Set Cursor Type

Chapter-15 Programming for Data Wipers

• Introduction
• When the data becomes completely unrecoverable
• Why data wiping is so important
• Writing program for Non - Destructive data wiper
  • Comments on logic and the coding of the program
• Writing program for Destructive Data Wiper
  • Comments on coding
• Wiping Data Area of specific file
  • Comments on logic and coding of program

Chapter-16 Developing more Utilities for Disks

• Introduction
• Hiding Partitions
• How the partition becomes hidden
  • Writing program to hide partition
  • Comments on coding
  • Writing program to Unhide the Partition
  • Comments on Program
  • Writing program to delete Partition
  • Comments on program
• Formatting "Track 0 Bad" floppy
  • Writing the Disk Editing Tool

APPENDIX