1. Storage and Multimedia

2. Storage Devices
Used to store data and programs permanently on storage media
Computer hardware component that writes and reads data to and from storage media
Writing data means recording data from memory to a storage medium
Reading or retrieving data means transferring data from storage medium into the computer memory for use by the operating system or application program

3. Storage Devices
Speed of the storage device and memory is defined by access time
Access time of storage device is measured as the amount of time that the storage device takes to locate and retrieve a specific data on the storage medium
Access time of storage device is slower than the access time of memory

4. Storage Devices Floppy Disk Zip Disk Hard Disk Magnetic Tape
CDs and DVDs

5. Types of Storage Devices
Magnetic Storage Devices
Optical Storage Devices
Mobile Storage Devices

6. Magnetic Storage Devices
Diskette drives, tape drives and hard disk drives are examples of magnetic storage devices
Used to write and read data to and from the storage devices
The surface of the diskettes, tapes and hard disks are coated with magnetic material such as iron oxide or ferrous oxide, which can be magnetized

7. Magnetic Storage Devices
The surfaces of disks and magnetic tapes are coated with million of tiny iron particles so that data can be stored on them
Each of these particles can act as magnet
The write/read heads of disk drives or tape drives contain electromagnets that generate magnetic fields in the iron on the storage medium as the head passes over the disk or tape

8. Magnetic Storage Devices
In reading process, no current is flowing through the electromagnetic and read/write heads have no magnetic field
Because the storage medium has a magnetic field but the head does not
The disk or tape drive senses the direction of the flow as the disk or tape passes by the head
Data is sent from the read/write head into memory in the form of electric pulses

9. Magnetic Disk Commonly used in computers as secondary storage
A magnetic disk is a circular metal or plastic disk coated on both sides with magnetic recording material
Data on magnetic disk is recorded as magnetic field
Data is stored on both sides of the disk, and each side has its own read/write head

10. Types of Magnetic Disk Floppy Disk or Interchangeable Disk
Hard Disk or Fixed Disk

11. Organizing Data on Magnetic Disk
Before to store the data on the magnetic disk, it is prepare through operating system
The disk surface is magnetically mapped
The process of mapping the surface of disk is called formatting or initializing

12. Disk Areas Windows operating system divides the disk into four areas:
Boot Master Record
File Allocation Table (FAT)
Root Folder
Data Area

13. Floppy Disk Magnetic storage media
Plastic disk coated on both side with magnetic recording material
Size of the disk refers to the diameter of disk and not refers to the storage capacity
High density disks are smaller in size but larger in storage capacity

14. Floppy Disk

15. Floppy Disk Drive
Hardware component used to write and read data to and from the floppy disk
It includes a motor that rotates the disk on the spindle
It also contains write/read head that writes and reads the data to and from the disk when disk rotates
Floppy disk rotates 300 revolutions per minute

16. Zip Disk Portable magnetic media
Storage capacity is about from 100MB to 800MB
Storage capacity is 100 times greater than floppy disk
More reliable than floppy disk

17. Hard Disk
Most commonly used storage device in personal computer and laptop computer
Most application program and operating system require hard disk for installation and operation
Also referred to as fixed disk

18. Hard Disk

19. Magnetic Tape
Plastic ribbon with width 0.25 inch to 1 inch and one side coated with magnetic recording material which can be magnetized
Divided into vertical columns called frames and each frame is further divided into horizontal rows called tracks
Magnetic tape drive is a device that writes/reads data from a magnetic tape

20. References
Introduction to Information Technology by Riaz Shahid, CM Aslam and Safia Iftikhar
The Concepts of Information Technology by Imran Saeed, Ahsan Raza, Tariq Mehmood and Zafar Hussain