Magnetism data addressing

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nanotechnology, magnetism, data addressing

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Magnetism data addressing

  1. 1. MAGNETIC DATA STORAGE AND RECORDING DATA ADDRESSING BY, A. POOJA SHUKLA M.Tech (NANO) Ist Yr 1821310006 SRM UNIVERSITY
  2. 2. DATA ADDRESSING  A data or information found in a particular address  A data can be randomly selected or easy to find in the given array with the help of the given address  Types of data addressing,  CHS  ECHS  LBA
  3. 3. ADVANTAGES  Write Protection  Erasing  Security  Removable media  Removable device  Managing
  4. 4. BIOS
  5. 5. • Basic Input Output System. • Is a set of initial code to run your PC. • Intel have designed their CPUs always to begin execution of code at address FFFF0. • The first instruction is a jump instruction to the main part of BIOS code which could be "anywhere" else • As well as testing and initializing the hardware in the Power On Self Test (POST)
  6. 6. For the purpose of booting up the computer, the BIOS is used for three main functions: – Providing a set of assembler subroutines that can be called by the operating system and whose function is to access the hardware components of the computer such as hard disk. – Initiates Power On Self Test (POST). – Allowing changes to the low level setup options. – Initiating the boot sequence after a hardware Reset.
  7. 7. ATA
  8. 8. A set of standards called the ATA (AT-Attachment) came into being in 1989 that effectively put a boundary on what was possible in terms of cylinder, head and sector numbers.
  9. 9. • ATA-5 says (amongst other things) that: – The cylinder number must be represented by 16 binary digits. – The head number must be represented by 4 binary digits. – The sector number must be represented by 8 binary digits. • A total of 28 bits.
  10. 10. CYLINDER – HEAD – SECTOR (CHS)
  11. 11. • CHS, Method for giving addresses to each physical block of data on a hard disk drive • It can be low level formatted to different capacities
  12. 12. • Identifying individual sectors on a disk by their position in a track • The track is determined by the head and cylinder number • For addressing the sector in smallest unit
  13. 13. Hard Disk Geometry Description Terminology Heads on a Platter Head A stack of Rings or "Tracks" Cylinder Segment Sector
  14. 14. Where the data is physically on the disk? • “disk controller” allows us to specify only the Cylinder, Head and Sector that we want to access • The disk controller calculates where the data is physically on the disk and hands the data back to us • More accurately CHS is a pointer in memory to the data.
  15. 15. How the physical disk is accessed If we wanted to access one particular sector, we could reference it by specifying –C which head it was on, –H which cylinder it was on and finally –S which sector it was on. That would then uniquely identify the sector that we wanted to access.
  16. 16. CHS Values • 16-bit Cylinder value (C) • 4-bit Head Value (H) • 8-bit Sector Value (S) • Old BIOS: – 10-bit C – 8-bit H – 6-bit S – Limited to 528MB disk
  17. 17. LOGICAL BLOCK ADDRESSING (LBA)
  18. 18.  Used for specifying the location of blocks of data stored  Generally in secondary storage system eg, hard disks  It is an simple linear addressing scheme  Blocks are arranged by an integer index example : LBA 0, LBA 1
  19. 19. The five most important things to note about LBA are: • LBA is a translation method based on the CHS addressing scheme • LBA was not (as many web sites claim) invented to overcome any disk size limits • It is simply a different way of accessing the hard disk • LBA does not require the BIOS to know anything about the disk geometry to access the disk • LBA is used to address data
  20. 20. EXTENDED CHS (ECHS)
  21. 21. • It is also called as large mode CHS • It uses BIOS translation method • It is inherited by CHS mode to be in given size barrier (504 MB)
  22. 22. • The BIOS coders agreed on a way round the 504 MB limitation. They came up with a system called “Enhanced CHS”, or ”ECHS”. • ECHS is a simple translation method written on the end of the interrupt INT13h. In summary, this is what happens: O/S --> INT13h --> ECHS Translation --> CHS call --> Disk Controller
  23. 23. • Consequently, the requirements for this type of disk access are as follows: An operating system that can make INT13h calls. A BIOS that understands INT13h calls. A BIOS that can perform the ECHS translations. A BIOS that can make CHS calls. A disk controller that understands the (translated) CHS values referenced.
  24. 24. Storage Characteristics • Volatility – Non-Volatile – Volatile • Mutability – Read/Write – Read Only – Slow Write, Fast Read Storage • Accessibility – Random Access – Sequential Access • Addressability – Location – File – Content
  25. 25. THANK YOU……!!

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