Floppy Disk Drive Problems in 386 Enhanced Mode

Last reviewed: July 26, 1995
Article ID: Q75488
The information in this article applies to:
  • Microsoft Windows operating system versions 3.0, 3.0a, 3.1, 3.11

SYMPTOMS

If you are experiencing errors reading, writing, or formatting floppy disk drives while running Windows in 386 enhanced mode, follow the steps listed below to troubleshoot and resolve the problem.

WORKAROUND

  1. Exit Windows.

  2. To determine whether your system is reading the floppy disk directory, insert a disk in drive A, and type the following at the MS-DOS command prompt:

    dir a:

    NOTE: If you remove the disk from drive A and type "dir a:" (without the quotation marks) and the directory lists again, it is an indication of an improper CMOS version or incorrect hardware setup (for example, a 3.5-inch drive on a jumper for an XT computer).

  3. To determine whether your system writes to the floppy disk drive, type the following at the MS-DOS command prompt

    copy <filename> a:

    where <filename> is any valid file on your hard disk.

    If the commands in steps 2 and 3 do not work, the problem is at the MS-DOS level.

  4. Restart your computer using the minimum information in your AUTOEXEC.BAT file and CONFIG.SYS file that your computer needs to start up. For more information about how to do this, query on the following words in the Microsoft Knowledge Base:

    troubleshooting and autoexec.bat and config.sys and files

    NOTE: Anti-Virus software commonly causes this problem.

  5. Does the floppy disk drive read problem go away when you run Windows in standard mode or real mode? To test this, start Windows by typing the following at the MS-DOS command prompt:

    win /s

    If everything works correctly in Windows, you know that the problem is related only to running Windows in 386 enhanced mode.

    If the problem is specifically related to 386 enhanced mode, you may be loading SYMEVNT.386 from Norton Utilities 8.0. For more information about SYMEVNT.386, query in the Microsoft Knowledge Base on the following words:

    symevnt.386 and norton

    If the problem is specifically related to 386 enhanced mode but you are not loading SYMEVNT.386, using the switches below may lessen the problem. Add these switches to the SYSTEM.INI file in the [386Enh] section in the order shown. If you find one of the switches works, you can try removing previous switches that had no effect. Note that the switches listed in item (b) should be added or removed as a pair. (See the MORE INFORMATION section of this article for an explanation of these switches.)

    a. IRQ9GLOBAL=YES

    b. HIGHFLOPPYREADS=NO EMMEXCLUDE=E000-EFFF

    c. VirtualHDIrq=OFF

  6. Insert a semicolon (;) before the Load= and Run= lines in the WIN.INI file to ensure that nothing else is being loaded that could cause a problem.

  7. Check to see if you can successfully issue commands in Windows at the MS-DOS command prompt. If commands work at the MS-DOS level, it indicates a BIOS or hard disk drive/floppy controller BIOS problem.

  8. Is the floppy disk drive icon displayed in File Manager? If not, check your BIOS version and contact your hardware manufacturer for an update.

  9. Disable any BIOS and video shadowing. Each computer may have a different way of disabling its shadowing. You will need to check your system documentation and follow the instructions provided there to perform this task.

  10. Check for third-party or external floppy disk drivers.

  11. Check the type and version of MS-DOS. MS-DOS versions earlier than 3.3 do not support 1.44-MB drives.

  12. Check for hardware devices that may be using the same IRQ as the floppy disk drive controller. (By default, the floppy disk drive controller uses IRQ 6.)

  13. Check to see if an IDE ATIO card is in use. This is an integrated card that contains a game port, serial port, parallel port, IDE, and floppy disk drive controller. Remove this card and insert a card that has only the IDE floppy disk drive controller on it.

MORE INFORMATION

The following paragraphs explain the switches used in step 5 above.

IRQ9Global=<boolean>

Default: No Purpose: If enabled, this switch converts IRQ9 masks to global. Enable

          this setting if your system stops responding (hangs) when
          accessing a floppy disk drive, or make sure your system accesses
          the floppy disk drive before you start Windows.

HighFloppyReads=<boolean>

Default: Yes Purpose: Normally, Windows turns a DMA verify to the area E000:0000-

         EFFF:FFFF into a read. In rare cases, this might cause the system
         to fail because some software might, as a result, write over the
         system's shadow RAM if you have it in this area. If this happens,
         disable this setting and set EMMExclude to E000-EFFF.

EMMExclude=<paragraph-range>

Default: None Purpose: Specifies a range of memory that Windows will not scan to find

          unused address space. This has the side effect of turning off the
          RAM and ROM search code for the range. The range (two paragraph
          values separated by a hyphen) must be between A000 and EFFF. This
          scanning can interfere with some adapters that use the same
          memory area. The starting value is rounded down and the ending
          value is rounded up to a multiple of 16K. For example, you could
          set EMMExclude=C800-CFFF to prevent Windows from scanning the
          addresses C800:0000 through CFFF:000F. You can specify more than
          one range by including more than one EMMExclude line.

VirtualHDIrq=<boolean>

Default: On

Purpose: If enabled, Windows in 386 enhanced mode can terminate interrupts

         from the hard disk controller, bypassing the ROM routine that
         handles these interrupts. Some hard disk drives may require this
         setting to be disabled for interrupts to be processed correctly.
         If this setting is disabled, the ROM routine handles the
         interrupts, which slows down system performance.


KBCategory: kbtshoot kbhw kbdisplay
KBSubcategory: win30 win31
Additional reference words: tshoot 3.00 3.00a 3.10 3.11 central point
norton format


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Last reviewed: July 26, 1995
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