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Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
Storage devices
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Storage devices

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  • 1. Lecture # 511/21/2012 Designed by Prof. Anosha Khan 1
  • 2.  Storage devices hold data, even when the computer is turned off.  The physical material that actually holds data is called a storage medium. The surface of a floppy disk is a storage medium.  The hardware that writes data to or reads data from a storage medium is called a storage device. A floppy disk drive is a storage device.  The two primary storage technologies are magnetic and optical.11/21/2012 Designed by Prof. Anosha Khan 2
  • 3. 11/21/2012 Designed by Prof. Anosha Khan 3
  • 4.  Surface of magnetic Disks and tapes are coated with millions of tiny iron particles so that data can be stored on them Read/Write heads of a magnetic disk or tape drive contains electromagnets that generate magnetic fields in the iron on the storage medium as the head passes over the disk11/21/2012 Designed by Prof. Anosha Khan 4
  • 5.  A storage device is the computer hardware that records and/or retrieves items to and from storage media Reading is the process of transferring items from a storage medium into memory Writing is the process of transferring items from memory to a storage medium11/21/2012 Designed by Prof. Anosha Khan 5
  • 6.  Access time measures:  The amount of time it takes a storage device to locate an item on a storage medium  The time required to deliver an item from memory to the processor 11/21/2012 Designed by Prof. Anosha Khan 6
  • 7.  Formatting is the process of dividing the disk into tracks and sectors so that the operating system can store and locate data and information on the disk Before a magnetic disk can be used, it must be formatted— a process that maps the disks surface and determines how data will be stored. During formatting, the drive creates circular tracks around the disks surface, then divides each track into sectors. The OS organizes sectors into groups, called clusters, then tracks each files location according to the clusters it occupies. 11/21/2012 Designed by Prof. Anosha Khan 7
  • 8.  Boot sector File allocation Table (FAT) Root folder Data Area11/21/2012 Designed by Prof. Anosha Khan 8
  • 9.  Tracks-  circular areas of the disk  Length of a track one circumference of disk  Over 1000 on a hard disk  Data first written to outer most track Sectors-  Divides tracks sections  On a floppy 9 sectors exits11/21/2012 Designed by Prof. Anosha Khan 9
  • 10.  Cylinders-  Logical groupings of the the same track on each disk surface in a disk unit Clusters-  Groups of sectors used by operating system  64 sectors in one cluster Partitioning: divide hard disk into separate areas called partitions; each partition functions as if it were a separate hard disk drive.11/21/2012 Designed by Prof. Anosha Khan 10
  • 11.  File Allocation Table(FAT) FAT32 New Technology file system (NTFS) NTFS 5 High performance File System (HPFS)11/21/2012 Designed by Prof. Anosha Khan 11
  • 12.  Uses magnetic storage technology Has read / write heads Includes a motor that rotates the disk on a spindle and read/ write head that can move to any spot on the disk’s surface as the disk spins Disk Density- the amount of data that a disk can hold To determine disk density multiply its total number of sectors by the number of bytes each sector can hold11/21/2012 Designed by Prof. Anosha Khan 12
  • 13.  Hard disks can store data using longitudinal recording or perpendicular recording Includes one or more platters mounted on a central spindle Each platter is covered with a magnetic coating It includes motor to spin platters and read/write heads11/21/2012 Designed by Prof. Anosha Khan 13
  • 14. 11/21/2012 Designed by Prof. Anosha Khan 14
  • 15.  An external hard disk is a separate free- standing hard disk that connects to your computer with a cable or wirelessly A removable hard disk is a hard disk that you insert and remove from a drive11/21/2012 Designed by Prof. Anosha Khan 15
  • 16.  Tape is a magnetically coated ribbon of plastic capable of storing large amounts of data and information A tape drive reads and writes data and information on a tape11/21/2012 Designed by Prof. Anosha Khan 16
  • 17.  An optical disc consists of a flat, round, portable disc made of metal, plastic, and lacquer that is written and read by a laser An optical disk is a high-capacity storage medium. An optical drive uses reflected light to read data. To store data, the disks metal surface is covered with tiny dents (pits) and flat spots (lands), which cause light to be reflected differently. When an optical drive shines light into a pit, the light cannot be reflected back. This represents a bit value of 0 (off). A land reflects light back to its source, representing a bit value of 1 (on).11/21/2012 Designed by Prof. Anosha Khan 17
  • 18.  A magnetic stripe card contains a magnetic stripe that stores information A smart card stores data on a thin microprocessor embedded in the card11/21/2012 Designed by Prof. Anosha Khan 18
  • 19.  A CD-Recordable (CD-R) drive lets you record your own CDs, but data cannot be overwritten once it is recorded to the disk. A CD-Rewritable (CD-RW) drive lets you record a CD, then write new data over the already recorded data. PhotoCD technology is used to store digital photographs. DVD recordable11/21/2012 Designed by Prof. Anosha Khan 19
  • 20.  Flash memory Smart Cards11/21/2012 Designed by Prof. Anosha Khan 20
  • 21. 11/21/2012 Designed by Prof. Anosha Khan 21

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