1. Computer Studies Today Chapter 18 1 »Two main types of secondary storage devices: –Magnetic storage devices –Optical storage devices

2. Computer Studies Today Chapter 18 2 Floppy Disks

3. Computer Studies Today Chapter 18 3 »Data are organised on a floppy disk in rings called tracks. »Each track is divided into sectors.

4. Computer Studies Today Chapter 18 4 »A floppy disk drive allows data to be read from or written to a floppy disk.

5. Computer Studies Today Chapter 18 5 Hard Disks A hard disk and a hard-disk drive A disk pack

6. Computer Studies Today Chapter 18 6 »The mechanism for reading or writing data on a hard disk is similar to that of a floppy disk. »The hard disk consists of several metallic platters and the drive has several access arms.

7. Computer Studies Today Chapter 18 7 »The access arms move several read-write heads in and out between the hard disks.

8. Computer Studies Today Chapter 18 8 »A way to organise data on a disk pack is the cylinder method.

9. Computer Studies Today Chapter 18 9 »Materials that can cause a head crash.

10. Computer Studies Today Chapter 18 10 »Hard disks have TWO advantages over floppy disks: –Hard disks provide larger capacities than floppy disks. –The access time for a hard disk is shorter.

11. Computer Studies Today Chapter 18 11 »The access mode of magnetic disks (floppy disks and hard disks) is direct access. »Data are recorded on or retrieved from the disks randomly.

12. Computer Studies Today Chapter 18 12 Magnetic Tape A cartridge tape and a cartridge tape unit

13. Computer Studies Today Chapter 18 13 »Magnetic tape is the cheapest secondary storage medium and is suitable for storing a large amount of data. »Data are recorded on or retrieved from the tapes sequentially.

14. Computer Studies Today Chapter 18 14 Optical Disks A CD-ROM driveOptical disks

15. Computer Studies Today Chapter 18 15 »The access mode of optical disks is direct access. »The storage capacity of optical disks is enormous and much larger than that of floppy disks.

16. Computer Studies Today Chapter 18 16 »Comparisons between floppy disks, hard disks, magnetic tapes and optical disks: