1. Copyright © 2002 Heathkit Company, Inc. All rights reserved. Unit 7 Floppy Drive Systems

2. 2 The Old Technologies Punch Cards Punched Tape Magnetic Tape

3. Start with a non-magnetic platter. Floppy Disk - Mylar Hard Disk - Metal, Ceramic, or Glass

4. 4 Coat with a thin layer of magnetic material. 4

5. 5 Two important characteristics of the magnetic surface: Coercivity Retentivity

6. 6 Coercivity How strongly the material resists changing its magnetic field. Must be high enough to resist changes by unintentional means. Must be low enough so that excess write current is not required. Generally, larger drive capacities require higher coercivity.

7. 7 Retentivity How well the magnetic material retains its magnetic field. Relates to how long a magnetic material can retain data without degradation.

8. 8 Magnetic domains randomly arranged (blank media)

9. 9 Pick-up device-Read/Write Head

10. 10 Magnetic domains orderly arranged (Recorded Media)

11. 11 Reading Data from the Disk

12. 12 Writing Data on a Blank Disk

13. 13

14. 14 The floppy disk surface is divided into tracks.

15. 15 Track 0 Track 1 Track 79

16. 16 Side 1, Track 0 Side 2, Track 0

17. 17 Read\Write Head Read\Write Head Disk Read/Write Head Read/Write Head

18. 18 One Sector = 512 Bytes

19. 19 Sector The smallest unit of storage on a disk. 512 bytes or 0.5k bytes Grouped into clusters

20. 20 Double-sided, double-density (DSDD) 5¼” Floppy Disk 40 tracks per side 9 sectors per track 360 sectors per side 2 sides 720 sectors total 360 KB total capacity

21. 21 Double-sided, high-density (DSHD) 5¼” Floppy Disk 80 tracks per side 15 sectors per track 1,200 sectors per side 2 sides 2,400 sectors total 1,200 KB total capacity

22. 22 Double-sided, double-density (DSDD) 3½” Floppy Disk 80 tracks per side 9 sectors per track 720 sectors per side 2 sides 1,440 sectors total 720 KB total capacity

23. 23 Double-sided, high-density (DSHD) 3½” Floppy Disk 80 tracks per side 18 sectors per track 1440 sectors per side 2 sides 2880 sectors total 1.44 MB total capacity

24. 24 High-density, 36-sectors (HD-36) 3½” Floppy Disk 80 tracks per side 36 sectors per track 2880 sectors per side 2 sides 5,760 sectors total 2.88 MB total capacity

25. 25 Floppy Drive Subsystem Components Drives Cables Controllers

26. 26

27. 27 Mother- board Mother- board

28. 28 5¼” Drive 5¼” Drive 5¼” Drive 5¼” Drive

29. 29 3½” Drive 3½” Drive 3½” Drive 3½” Drive

30. 30 Drive A “After twist” Drive A “After twist” Drive B “Before Twist” Drive B “Before Twist”