Floppy Drives

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Chapter 5

• Floppy Drives

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You Will Learn

• How data is stored on floppy disks
• How to use DOS and Windows commands to manage
  disks
• How to replace or install a disk drive

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Floppy Disk Drive and Connections
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Introduction to How Data Is Physically Stored on
a Disk
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How Data Is Physically Stored on a Disk

• Tracks
• Concentric circles of a disks surface
• Sector
• One pie-shaped segment of a track
• Almost always contains 512 bytes of data
• Formatting
• Process of preparing a new floppy disk for use by
  placing tracks on its surface to store information

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Tracks and Sectors
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How Data Is Physically Stored on a Disk
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Read/Write Head

• A sealed, magnetic coil device that moves across
  the surface of a disk to read/write data to the
  disk

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Read/Write Head
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How Data Is Logically Stored on a Disk

• Cluster
• Smallest unit of data that can be read from or
  written to a disk at one time
• Also called file allocation unit

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How Data Is Logically Stored on a Disk
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The Formatting Process

• Windows 9x or DOS FORMAT command
• Creates the tracks and sectors by writing tracks
  as a series of F6s in hex and, as necessary,
  writing the sector address mark to identify the
  beginning sector on a track
• Creates the master boot record
• Creates two copies of the file allocation table
  (FAT)
• Creates the root directory

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Creating the Tracks and Sectors

• The FORMAT command is a DOS and Windows 9x
  command that prepares a disk for use
• First step erases any data on the disk

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The Master Boot Record (MBR)

• The record written near the beginning of a floppy
  disk
• Contains information about the disk as well as
  the startup operating system programs

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The File Allocation Table

• A table on the disk that tracks the clusters used
  to contain a file

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The Root Directory

• The main directory on a disk (often represented
  as C\ on a hard drive)
• Typically contains other directories, such as
  Windows and MSOffice

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Using DOS to Manage a Floppy Disk

• Internal DOS commands
• DOS commands whose coding is contained within
  COMMAND.COM program and are therefore
  automatically loaded into memory when COMMAND.COM
  is loaded
• External DOS commands
• Stored as separate program files in DOS directory

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Using Windows 9x to Manage a Floppy Drive

• Format a disk and make a system disk using
  Windows 9x
• Copy Disk command using Windows 9x
• Emergency Startup disks

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Formatting a Disk Using Windows 9x
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Formatting a Disk Using Windows 9x
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Copy Disk Command Using Windows 9x
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Emergency Startup Disks (ESD)

• Serves Windows 9x as a rescue disk (floppy disk
  that can be used to start up computer when hard
  drive fails to boot)
• Also contains some Windows 9x diagnostic and
  utility files

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Exchanging and Supporting Floppy Drives

• Problems that can occur with a floppy drive and
  its support system
• How to replace the drive and controller card
• How to add an additional floppy drive to a
  computer system
• Why a floppy drive may not be able to read a disk

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When a Floppy Disk Drive Doesnt Work

• Check simple things first
• Make sure cables are connected
• Try a different disk (the floppy disk may have
  been damaged)
• If possible, try another drive
• If the 2nd drive works, the 1st drive is bad

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Common Error Messages

• Non-system disk or disk error
• Invalid or missing COMMAND.COM
• Incorrect DOS version
• Invalid drive specification
• Not ready reading drive A
• General failure reading drive A
• Track 0 bad, disk not usable
• Write-protect error writing drive A

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Replacing a Floppy Drive

• Check that computer and peripherals are working
• Turn off computer and remove cover (Figure 5-12)
• Unplug data cable and power cable from old drive
  and unscrew and dismount drive (Figure 5-13)
• Slide new drive into the bay reconnect data
  cable and power cable (Figure 5-14)
• Turn computer on check setup test the drive

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Check That Computer and Peripherals Are Working

• Turn on computer and verify that it boots to the
  OS with no errors
• Open a program and perform a task from the
  program
• Get a directory listing of files on a floppy disk
  and a CD-ROM
• Do a ScanDisk

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Turn off Computer and Remove Cover
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Unplug Data and Power Cables Unscrew and
Dismount Drive
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Slide New Drive Into Bay Reconnect Cables
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Turn Computer On Check Setup Test the Drive

• If all is well, replace the cover

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Adding a New Drive

• Requirements
• An empty bay
• An extra power cable
• An extra connection on the floppy drive
  controller card
• Slide drive into the bay, screw it down, connect
  the cable and power cable, and change setup

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Removable Drives

• Advantages
• Increase overall storage capacity of a system
• Make it easy to move large files from one
  computer to another
• Serve as a convenient medium for making backups
  of hard drive data
• Make it easy to secure important files
• Can be either external or internal (latter should
  be Plug and Play compliant)
• Consider drop height and half-life

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High-Capacity Disk Drives

• 3 ½-inch Zip drive (Iomega)
• SuperDisk LS-120 drive (Imation)

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Zip Drive

• Stores 100 MB or 250 MB of data
• Has a drop height of 8 feet
• Internal
• Costs less than 100
• Uses an IDE interface
• External
• Plugs into a parallel port, a USB port, or a SCSI
  port
• Consider it an add-on, not a replacement for
  standard 3 ½-inch disk drive

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Zip Drive
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Hard Disk Removable Drives

• E.g., Jaz drives (Iomega)
• Stores 1 GB or 2 GB or data
• Both internal and external models use a SCSI
  connection
• Has a drop height of 3 feet

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SuperDisk

• Holds 120 MB of data
• Is backward compatible with double-density (720K)
  and high-density (1.44 MB) floppy disks
  (advantage over Zip drive)
• Up to 27 times faster than regular floppy drives
• Can be purchased as external (parallel port and
  USB) or internal drives for about 75

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Chapter Summary

• Data storage on a floppy disk
• Management of data stored on a floppy disk
• Installing a floppy disk drive on a PC
• Prevalence and popularity of floppy drives
• Easy convenience and ready availability
• Low cost of disks
• Proven usefulness and dependability
• How the OS logically views the data stored on a
  floppy disk
• Removable drives