Logical Approach to Disks and OS

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