Troubleshooting DMF Floppy Disks

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This article was previously published under Q118580

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SYMPTOMS

Typing the MS-DOS directory command (DIR) on a standard floppy disk or a DMF floppy disk results in garbage characters or unsuccessful reads.
Switching floppy disks that are the same density but are formatted differently (for example, a 1.44-MB high-density disk is exchanged for a 1.68-MB high-density disk) results in garbage characters or unsuccessful reads.

For example, after Setup is finished with Disk 1 (1.44-MB), it asks for Disk 2 (1.68-MB or DMF). Even though Disk 2 is in the floppy drive, Setup continues to ask for it because it cannot distinguish between the disks.

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If change-line support is not working properly, accessing a distribution media format (DMF) floppy disk fails.

Change-line support informs MS-DOS when a disk and/or the format of a disk has changed. If MS-DOS determines the format of the first disk but does not realize that the formatting of the second disk is different, the second disk cannot be read.

It is also possible that a virus can cause this problem.

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RESOLUTION

Before beginning the following steps, consult with your computer manufacturer to ensure that your CMOS settings are correct.

The following steps help you determine whether change-line support is the cause of your problem:

Start your computer with a clean boot. For more information about clean booting, please query on the following words in the Microsoft Knowledge Base:
clean and boot and windows
NOTE: On a Windows 95-based machine, return to the earlier version of MS-DOS by pressing the F4 key when you see the message "Starting Windows."
Insert a non-DMF disk in drive A or drive B and then type the following commands at the MS-DOS prompt:
a: (or b:)
dir
If the above commands work successfully, insert a DMF disk and type the following command:
dir
If the second DIR command fails, garbage characters appear on the screen, or subsequent reads of the floppy disk fail (during Setup or otherwise), insert the following statement at the end of the Config.sys file and reboot your computer:
```
For a 1.44-MB A: drive     For a 1.44-MB B: drive
-------------------------------------------------
DRIVPARM=/d:0 /f:7         DRIVPARM=/d:1 /f:7
```
NOTE: Since the /c switch is not included, MS-DOS is instructed to not depend on change-line support. If your CONFIG.SYS file contains a DRIVER.SYS line, disable it by placing the REM command immediately preceding the line.
Repeat steps 2 and 3.
- If the above steps work successfully, change-line support is not functioning properly--leave the DRIVPARM statement in your Config.sys file.
- If the above steps fail, remove the DRIVPARM statement from your Config.sys file and consult with your computer manufacturer to ensure that your CMOS settings are correct.

You should also run a virus detection utility to determine if your computer is infected with a virus.

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