A+ Guide to Managing and Maintaining Your PC Fifth Edition Chapter 7 Floppy Drives

2 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Floppy Drives 3.5 inch 1.44 Mbytes Usages  Data transfer  Small file backup  Software distribution, e.g., device drivers

3 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Floppy Drive Subsystem

4 A+ Guide to Managing and Maintaining Your PC, Fifth Edition How Data Is Physically Stored on a Floppy Disk In concentric circles (tracks or cylinders)  Each track is divided into sectors  Each sector holds 512 bytes of data

5 A+ Guide to Managing and Maintaining Your PC, Fifth Edition How Data Is Physically Stored on a Floppy Disk

6 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Floppy Disk Each bit is a magnetized, rectangular spot Two read/write heads Head actuator: physically positions the read/write heads over the correct track Spindle motor: spins the floppy disk Tunnel-erase heads: erase any stray magnetic information recorded outside the defined track it is writing

7 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Inside a Floppy Disk Drive

8 A+ Guide to Managing and Maintaining Your PC, Fifth Edition How Data Is Physically Stored on a Floppy Disk

9 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Formatting a Floppy Disk Low-level formatting: recording the tracks and marking the start of each sector on each track High-level formatting: creating the disk's logical structures such as the file allocation table and root directory

10 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Ways to Format a Floppy Disk Format command from a command prompt Windows Explorer, right-click the 3½ Floppy (A:) icon and select Format on shortcut menu

11 A+ Guide to Managing and Maintaining Your PC, Fifth Edition 3.5 inch Floppy Disk Geometry 2 sides 80 tracks/side 18 sectors/track 512 bytes/sector Storage capacity =

12 A+ Guide to Managing and Maintaining Your PC, Fifth Edition How Data Is Logically Stored on a Floppy Disk Cluster  Smallest logical unit of space allocated and accessed by the operating system  On a 3½-inch high-density floppy disk, one cluster = one sector (512 bytes)

13 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Project 1: Data are Allocated in Clusters? Insert a floppy disk, check its space usage Create a file with only one letter and save it to the floppy disk Check the space usage again

14 A+ Guide to Managing and Maintaining Your PC, Fifth Edition High-level Formatting of a Floppy Creates boot record Creates two copies of file allocation table (FAT) Creates root directory

15 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Boot Record First sector of the disk (track 0, sector 1 (bottom of the disk, outermost track)) Stores basic information about how the disk is organized Has a bootstrap loader that can be used to boot from the disk

16 A+ Guide to Managing and Maintaining Your PC, Fifth Edition File Allocation Table (FAT 12) One-column table  Width of each entry in the column is 12 bits Records  Location of the next file cluster  Unused/Bad status

17 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Root Directory Table A table with a fixed number of entries, each for a file or a subdirectory under the root directory Each entry  File name and extension  Time and date of last update  File size  File attributes  Starting cluster

18 A+ Guide to Managing and Maintaining Your PC, Fifth Edition How the OS Uses the FAT and Directory Table

19 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Common Error Messages Non-system disk or disk error. Replace and strike any key when ready. No operating system found. Bad or missing COMMAND.COM Error in Config.sys line xx Himem.sys not loaded Missing or corrupt Himem.sys

20 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Common Error Messages Invalid Drive Specification Not ready reading drive A:, Abort, Retry, Fail? General failure reading drive A:, Abort, Retry, Fail? Track 0 bad, disk not usable Write-protect error writing drive A:

21 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Project 2: Replacing a Floppy Drive 1.Check that computer and other peripherals are working 2.Turn off computer and remove cover 3.Unplug data cable and power cable from old drive; unscrew and dismount the drive 4.Slide new drive into the bay; reconnect data cable and power cable 5.Turn on computer; check setup; test the drive; turn off computer and replace the cover