


                               User's Manual
                         Device Driver for IDE-MO
                       ============================

          for MS-DOS 6 and Windows(R) 3.1, Windows for Workgroups 3.11
                      for IBM PC/AT and compatibles


                             FUJITSU LIMITED

                               October/1996






All Rights Reserved, COPYRIGHT (C) FUJITSU LIMITED 1995,1996





Contents of this document is subject to change without notice.
No part of this document may be reproduced in any form or by any means.

Windows, MS-DOS, and Windows NT are either registered trademark or trademark
of Microsoft Corporation.
IBM, PC, AT and OS/2 are either registered trademark or trademark of 
International Business Machines Corporation.
Other company names and product names are registered trademarks or trademarks
of their respective companies.





Table of Contents
=================
1. Preface
  1.1  Contents of the package

2. Notes and Restrictions
  2.1 NOTE
  2.2 RESTRICTIONS

3. Installation
  3.1  Installation program
  3.2  Manual installation

4. BIOS Registration

5. Outline of the Device Driver
  5.1  Functional overview
  5.2  Operating environment (hardware)
  5.3  Operating environment (software)
  5.4  Supported drive
  5.5  Supported physical formats of MO disks
  5.6  Supported logical formats of MO disks

6.  Details of Device Driver
  6.1  Syntax
  6.2  KILLDRV.EXE functions
  6.3  Loading driver in main memory
  6.4  Drive letter assignment
  6.5  Supported logical formats
  6.6  Compatibility with other systems
  6.7  Formatting utility FJFDISK
  6.8  Built-in Formatting function of DOS
  6.9  Software configuration

7. Writing to write-protected disks
  7.1  DOS 6
  7.2  Windows 3.1 or WFW3.11
  7.3  Smartdrv

8. Other considerations

9. Trouble-Shooting
  9.1 Hardware Trouble
  9.2 Software Trouble
  9.3 MO media trouble

APPENDICES
APPENDIX A: Why is the device driver necessary?

APPENDIX B: Why is KILLDRV necessary?
  B.1  Outline
  B.2  What if KILLDRV is neglected?





1. Preface
==========
Thank you for using Fujitsu's M2541B magneto-optical (MO) disk drive. 
The device driver, MODSIKP.SYS, in this package allows you to use M2541B 
in the DOS 6 and Windows 3.1/WFW3.11 environment.


1.1  Contents of the package
----------------------------
MODISKP.SYS     Device driver.
MODISKP.TXT     The guideline file you are reading now.
KILLDRV.EXE     Supplemental program that disables the drive letter assigned 
                by DOS internal disk driver.
FJFDISK.EXE     Formatter.
FJFDISK.TXT     Instructions for the formatter.
NSR.TXT         Explanation of the NSR format.
INSTALL.EXE     Installer.
INSTALL.MSG     This file is used by the installer (do not modify this file).
INSTALL.GID     Quick reference shown by the installer.
CHKLIST.TXT     Check list for troubleshooting.

*) The program contents is subject to change without notice.





2. Notes and Restrictions
==========================
2.1 NOTE
--------
(1) Use M2541B without registration to BIOS as much as possible.

   In the case you use it with BIOS registration, do not forget to run KILLDRV
   in your AUTOEXEC.BAT.
   Installer will automatically modify your AUTOEXEC.BAT to run KILLDRV.EXE.

(2) In order to format MO media, use FJFDISK.EXE as much as possible.

   Although FDISK and FORMAT command which is included in DOS can format MO 
   media, use FJFDISK.


2.2 RESTRICTIONS
----------------
(1) "Copy Disk" or "Format Disk" of DISK menu in file manager of Windows 3.1 
    or WFW 3.11 cannot be used for MO disk.

(2) FORMAT command cannot be performed in DOS prompt in Windows3.1 or 
    in WFW3.11.





3.  Installation
================
3.1  Installation program
-------------------------
The source of installation need not be a floppy disk.
For example, you can make a sub-directory on your hard disk, and copy all the 
necessary files to that sub-directory before installation.
The following description assumes that the installer is in floppy
disk drive A:.

(1) Set A:\ as the current drive.

(2) Type the following at the DOS prompt:
>INSTALL [Enter]

[Enter] means to press the [Enter] key.

(3) Follow the on-screen instructions.

(4) When the installation is complete, re-start your computer.


The installer automatically performs the following:

(1) Creates the \FJMO directory on drive C:.

(2) Copies the following files to the C:\FJMO directory:
MODISKP.SYS
MODISKP.TXT
KILLDRV.EXE
FJFDISK.EXE
FJFDISK.TXT
NSR.TXT
INSTALL.EXE
INSTALL.MSG
INSTALL.GID
CHKLIST.TXT

(3) Adds the following line to the last line of C:\CONFIG.SYS.
DEVICE=C:\FJMO\MODISKP.SYS

(4) Adds the following line to C:\AUTOEXEC.BAT.
C:\FJMO\KILLDRV


3.2  Manual installation
------------------------
To install the device driver manually, perform steps (1) to (4) above 
by yourself. 
Then, re-start your computer.

Make sure that step (4) is implemented.





4. BIOS Registration
====================
Do not register the M2541B MO drive to BIOS whenever possible. 
This device driver accesses the MO drive without using the BIOS functions.
So this driver works well with or without BIOS registration.

  The method of BIOS setting differs slightly for each PC. 
  Use the BIOS Setup program, and set "NONE" or "DISABLE" for the IDE port 
  connected to the M2541B.

With some BIOSes, the computer may not start up if the IDE port is not 
registered. In this case, register the IDE port in the BIOS, and be 
careful of the following:

(1) Different drive letters are assigned to the drive according to the media 
  inserted when the computer starts.
  When an AT hard disk format media is inserted, DOS internal disk driver
  (IO.SYS)  assigns drive letters to the MO drive.
  In other cases, DOS internal disk driver does not assign drive letters 
  to the MO drive.

(2) Use of OS/2 Boot Manager may result in unexpected problems.
  For example, confusion occurs when the BIOS on the SCSI board is enabled 
  and a SCSI hard disk is registered in Boot Manager. 
  This is because the disk number assigned to the SCSI hard disk differs 
  depending on whether a disk is inserted in the M2541B.

(3) When using the System Commander boot utility, do not start the computer 
  with the MO media inserted in M2541B. 
  Otherwise, the MO disk may be destroyed.
  (The first sector of the media may be modified.)




5. Outline of the Device Driver
===============================
MODISKP.SYS

5.1  Functional overview
------------------------
The device driver supports Read/Write and disk change of the IDE-MO drive in 
the DOS environment. 
Since the device driver accesses the hardware directly, Read/Write can be 
performed without support by the ROM BIOS.


5.2  Operating environment (hardware)
-------------------------------------
The following hardware is necessary for the operation of this device driver:
1) IBM PC/AT or compatible
2) Fujitsu MO drive (IDE MO drive)


5.3  Operating environment (software)
-------------------------------------
1) DOS version 5 or later


5.4  Supported drive
--------------------
(1) Removable disk drive with IDE interface
    Especially, FUJITSU's "M2541B" is supported.

(2) Boot drive(DOS starts up from which) is NOT mounted.

(3) IDE-MO drive connected to PC with PCMCIA card is NOT mounted.


5.5  Supported physical formats of MO disks
-------------------------------------------
3.5-inch MO disks
1) 128 Mbytes total capacity, 512 bytes per sector
2) 230 Mbytes total capacity, 512 bytes per sector


5.6  Supported logical formats of MO disks
------------------------------------------
(1) Volume format (partitioning method)
- Super floppy format
- AT hard disk format
- NSR format

* For details of each format, see Section 6.7.

(2) File format in each partition (file system)
- FAT (file allocation table)

  The FAT file system is used by DOS, and is supported by Windows 95, 
  Windows NT, and OS/2.





6.  Details of Device Driver
============================
6.1  Syntax
------------
Register the device driver in the CONFIG.SYS file as described below. 
The description is not case-sensitive.

DEVICE=(path)\MODISKP.SYS [/P][/Ii][/Rr]
or
DEVICEHIGH=(path)\MODISKP.SYS [/P][/Ii][/Rr]

    /P    Pause option
    Pauses screen messages after the device driver is initialized during the 
    computer starting process.
    Pressing any key continues the operation.
    Specify this option in order to check the message displayed by the 
    device driver.

    /Ii    Device number option
    Only the device connected to port i is mounted.
    Where i is defined as:
      1=Primary Master
      2=Primary Slave
      3=Secondary Master
      4=Secondary Slave
    If this option is not specified, all ports are scanned. 
    Therefore, this option need not be specified usually.

    /Rr    Reserved drive option
    Specify the number of reserved logical drive letters (r).
    If this option is not specified, one drive letter is reserved.
    The number of logical drive letters assigned will be the larger of 
    the number of partitions on the disk inserted at starting and r.


6.2  KILLDRV.EXE functions
--------------------------
When the M2541B is supported by ROM BIOS, KILLDRV disables the drive letter 
assigned by DOS internal disk driver(IO.SYS).
The MO drive cannot be accessed by the drive letter assigned by IO.SYS.

    If accessed, message of "Invalid drive specification" will be displayed 
    and access denied.

The MO drive can be accessed only by the drive letter assigned by this device 
driver.

In the following cases, the DOS internal disk driver does not assign a 
drive letter to the M2541B:
 
    1) The M2541B is not registered to BIOS.
    2) The M2541B is registered to BIOS, but no disk is inserted upon 
       starting up the computer.
    3) The M2541B is registered to BIOS, but the disk inserted upon 
       starting the computer is not an AT-HDD type formatted.

In the above three cases, KILLDRV performs nothing.

For more information, see the APPENDIX.


6.3 Loading driver in main memory
---------------------------------
This device driver will not be loaded in main memory in the following cases:
In the case, driver is not loaded, the message "Driver not loaded." will be 
displayed.

(1) In the case, the drive cannot find the MO disk drive to be mounted.

(2) In the case, the driver is doubly registered in CONFIG.SYS, the second 
    driver will not be loaded.

Note1) In order to check the driver is loaded or not, run C:\FJMO\CHKDD.COM.
       It will show the drive-letter corresponding to MODISKP.SYS.

This MO disk device driver stays resident with about 10 kByte in memory.
The more number of reserved drive letters, the larger in memory size.


6.4  Drive letter assignment
----------------------------
(1) If the disk inserted upon starting the computer has more partitions than 
  the number specified with the /R option, as many drive letters as the number 
  of partitions are assigned to the MO drive.

  For example, if the /R2 option is specified in CONFIG.SYS and the computer 
  is started with a three-partition disk, three drive letters are assigned 
  to the MO drive.

(2) If a disk inserted in the MO drive has more partitions than the number of 
  drive letters assigned to the MO drive, the driver can access only as 
  many partitions as the number of drive letters assigned to the MO drive.

  For example, assume that two drive letters are assigned to the MO drive.
  If the MO disk with three-partitions is inserted, the driver cannot access 
  the third partition.

(3) If a disk inserted in the MO drive has fewer partitions than the number 
  of drive letters assigned to that drive, an error occurs when the driver
  attempts to access the excess drive letter.

  For example, if two drive letters (D: and E:) are assigned to the MO drive.
  Then a single-partition disk is inserted, the driver can access that disk 
  using drive letter D:. However, if an attempt is made to access the disk 
  using drive letter E:, an error occurs and the "Invalid media type" 
  message is displayed.


6.5  Supported logical formats
------------------------------
The device driver automatically detects the following three types of format 
and assigns logical drive letters (such as D: or E:).

- Super floppy format
  A de-facto standard MO format. 
  The entire disk is handled as one logical drive. 
  This format is generally called the IBM format.
  Use the attached FJFDISK program to make this format.

- AT hard disk format
  A format with partitions, used with hard disks for PC/AT compatibles. 
  One MO disk can be divided into multiple partitions. 
  Use the attached FJFDISK program or the FDISK command of DOS to make this 
  format.

- NSR format (NSR volume format)
  An international standard (ISO13346) that divides an optical disk into 
  multiple partitions. 
  One MO disk can be divided into multiple partitions (logical drives).
  NSR is an acronym for ISO13346 and stands for Non-Sequential Recording.
  Use the attached FJFDISK program to make this format.

* The driver assumes an unformatted MO disk if the MO disk is in any other 
format or has no valid partition.


6.6  Compatibility with other systems
-------------------------------------
The driver can read data from and write data to an MO disk formatted by the 
following operating systems:

* Compatibility table (Read/write of MO disks formatted by other systems)

     -------------------------------------------------------------------------
     OS          Formatter                  Disk format
     -------------------------------------------------------------------------
     DOS 5, 6   OS utility(FDISK(*1)+FORMAT) AT hard disk format
                Fujitsu (FJFDISK)            Super floppy format
                                             AT hard disk format 
                                             NSR format

     Windows 95  OS utility                  Super floppy format
        (FDISK(*2)+FORMAT in DOS prmpt Mode) AT hard disk format

     Windows NT  OS utility(SCSI-MO)         AT hard disk format(FAT files only)
                 Fujitsu formatter(SCSI-MO)  Super floppy format
                                             AT hard disk format
                                             NSR format

     OS/2        OS utility(SCSI-MO)         Super floppy format
                 Fujitsu formatter(SCSI-MO)  Super floppy format
                                             AT hard disk format
                                             NSR format
     -------------------------------------------------------------------------
Notes:
*1 Need to set up the BIOS of your computer, refer to the manual 
   of your computer.
*2 Need to check the [Int13 unit]check box in the device manager.


6.7  Formatting utility FJFDISK
--------------------------------
(1) This package includes a formatting utility, FJFDISK.EXE. 
    This utility performs physical and logical formatting of MO disks. 
    The following formats can be generated:

      1) Super floppy format
      2) NSR format
      3) Hard disk format

    For more information, read FJFDISK.TXT.

(2) If a logically unformatted disk is accessed in DOS, the error message
    "Invalid media type" 
    is displayed.

    If a logically unformatted disk is accessed in Windows 3.1 or WFW3.11, 
    the error message
    "Drive * does not exist"
    is displayed.

    In these cases, use FJFDISK to format the disk.

(3) If a physically unformatted disk is accessed in DOS, the error message
    "Not ready reading..."
    is displayed.

    If a physically unformatted disk is accessed in Windows 3.1 or WFW3.11, 
    the error message
    "Not ready"
    is displayed.

    In these cases, use FJFDISK to format the disk physically.


6.8  Built-in Formatting function of DOS
----------------------------------------
MO disks can be formatted by the built-in formatting command of 
DOS (FDISK and FORMAT). 
The function of these commands are similar to FJFDISK, so use FJFDISK 
whenever possible.

The outline of the FDISK and FORMAT commands are described below. 
For more information, refer to the user's manual of DOS.

(1) FDISK
    Generates partitions on a disk.
    FDISK does not format each partition.
    To format each partition, re-start the computer and use the FORMAT command.

    To execute FDISK on M2541B, it is necessary to register the M2541B drive 
    to BIOS.

(2) FORMAT
    FORMAT command have the following functions:
    - Formats each partition if a disk is divided into partitions
    - Formats the un-formatted disk into the super floppy format


    [Note 1]
    Two different type disks cannot be formatted successively.
    In order to format two or more disks using FORMAT, terminate FORMAT 
    command each time and re-start FORMAT command with the next disk inserted.

    Two or more un-formatted media with the same capacity are successively 
    formatted.

    [Note 2]
    If you stopped formatting with "Ctrl + C", MIRROR.FIL file remains 
    on the disk.
    This file is data for UNFORMAT command. You can delete it.

    [Note 3]
    "Format Disk..." menu item of Windows 3.1 or WFW3.11 File Manager 
    does not work with MO drive. 
    Also "Copy Disk..." menu item of Windows 3.1 or WFW3.11 File Manager 
    does not work with MO drive. 

    [Note 4]
    Format command does not work in DOS prompt of Windows 3.1 or WFW3.11.


6.9  Software configuration
---------------------------
This device driver accesses the I/O port directly to control the MO drive.

The figure below shows the software configuration of the device driver.

                   +--------------------------+
                   | DOS (Version 5 or later) |
                   +--------------------------+
                               |
                   +--------------------------+
                   |     MODISKP.SYS          |
                   +--------------------------+
                               |
                         (ATA command)
                               |
                   +--------------------------+
                   |        I/O port          | (Primary or secondary)
                   +--------------------------+
                               |
                   +--------------------------+
                   |     IDE MO drive         |
                   +--------------------------+





7. Writing to write-protected disks
===================================
7.1  DOS 6
----------
    When an attempt is made to write data to a write-protected disk, the 
    following error message is displayed and the processing is paused:

    Write protect error writing drive *
    Abort, Retry, Fail?

    Remove the disk, release the write protect, re-insert the disk, and then 
    select "Retry" or simply select "Abort".

7.2  Windows 3.1 or WFW3.11
---------------------------
(1) When an attempt is made to write data to a write-protected disk, 
    the following error message is displayed and the processing is paused:

    "Write protect error"

    Click on [OK], remove the disk, release the write protect, re-insert 
    the disk, and resume the operation.

(2) The error message is not displayed when an attempt is made to write 
    a file with a size of less than 512 bytes to a write-protected disk. 
    Of course, no operation is performed on the disk.

(3) The error message 
    "The specified directory already exist" 
    will be displayed when an attempt is made to create a directory on 
    a write-protected disk.
    No new directory is made and no such directory exist.


7.3  Smartdrv
--------------
By default, the Smartdrv write cache is OFF for MO drives.
It can be set to ON.

When the Smartdrv write cache is ON for MO drives, NEVER attempt to write
data to a write-protected disk.

The followings are what happens when writing to write-protected disk:

(1) DOS environment
  If you attempt to write data to a write-protected disk while the Smartdrv
  write cache is ON, the following error message is displayed;

A serious disk error ha occurred while writing to drive *
Retry (r) ?

  Then remove the disk, release the write protect, re-insert the disk, 
  and press "r" key. You have no choice.

(2) Windows environment
  If you attempt to write data to a write-protected disk while the Smartdrv
  write cache is ON, blue display appears with error message:

"A serious disk error has occurred while writing to drive *."

  Then remove the disk, release the write protect, re-insert the disk,
  and press any key. And continue your work.





8. Other considerations
=======================
(1) Do not use this device driver with other device drivers 
    which controls M2541B.

(2) Maximum number of drive letters
    This device driver assigns drive letters up to Y:. 
    If the number of drive letters specified with the /R option exceeds Y:, 
    the driver assigns drive letters up to Y:. 
    Similarly, if a disk with more partitions than Y: is inserted when 
    the computer is started, the driver assigns drive letters up to Y: 
    and ignores the rest of the partitions.

(3) Lastdrive specification
    The Lastdrive specification (LASTDRIVE=*) in CONFIG.SYS does not affect 
    the drive letter assignment of the MO drive.
    For example, if LASTDRIVE=H: is specified, drive letters I: and later 
    can be assigned by specifying a large value for the /R option.

(4) Drive letters for CD-ROM drives
    If this driver assigns a later drive letter than the drive letter 
    specified by LASTDRIVE=* (default is E:) in CONFIG.SYS, no drive 
    letter can be assigned to a CD-ROM drive. 
    In such a case, the CD-ROM drive cannot be accessed. 
    To solve this problem, increase the value specified for LASTDRIVE=.

(5) The "Copy Disk..." and "Format Disk..." menu items of Windows 3.1 
    or WFW3.11 File Manager do not work on MO drives. 

    FORMAT command cannot be used in DOS prompt in Windows3.1 or WFW3.11.

(6) In DOS window in Windows3.1 or WFW3.11, accessing the MO drive without 
    media or drive with unformatted media results in displaying error 
    message in full-screen DOS.

    Follow the instruction and then press "Alt + Enter" to return to DOS 
    window.

(7) When ejecting a disk or inserting a disk to M2541B, Pressing 
    "Ctrl + Alt + Delete" key is ignored. Retry after busy lamp is go out.

(8) Do not disconnect the power supply or signal line of the M2541B 
    when the computer is running.
    (Usually, the power supply and signal line are built in and cannot be 
    disconnected.)

    The device driver cannot handle disconnection of the power supply or 
    signal line. 
    Disconnecting the power supply or signal line may result in unexpected 
    errors.

(9) Note the following when using System Commander:
    Do not register the M2541B in BIOS. 
    Use the BIOS Setup program to set "DISABLE" or "NONE". 
    If the M2541B is registered in the BIOS, use of System Commander may 
    destroy the disk. (The first sector of the disk may be edited.)





9. Trouble-Shooting
===================
This section helps you if you encounter problems when using IDE-MO drive.
There are following three troubles which causes problem:

  - Hardware trouble
  - Software troubles
  - MO media troubles

Check list, CHKLIST.TXT, is attached. When you have problem, print out 
CHKLIST.TXT and check each items on the list.
The followings are the same list as CHKLIST.TXT.

9.1 Hardware Trouble
--------------------
(1) Is power supply cable firmly connected ?

(2) Is signal cable firmly connected ?

(3) Is Master/Slave setting correct ?

9.2 Software Trouble
-------------------
(1) Is this device driver registered in CONFIG.SYS ?

(2) If you specify /I option, specified port address is correct ? 
    Is it Coincide with port address which M2541B is connected ?

(3) Is DOS booted from M2541B ?
    This device driver does not read/write the boot drive.

In order to know whether device driver is loaded, run CHKDD.COM in C:\FJMO.
If MODISKP is loaded, the drive-letter assigned by MODISKP will be shown 
as follows:

>Installed Block Device Driver Checker (CHKDD)   Version 1.07
>ALL RIGHTS RESERVED, COPYRIGHT (C) FUJITSU LIMITED 1993-1996
>
>        Device Driver Installation Status
>        Drive     SCSI ID    DeviceDriver Name
>------------------------------------------------
>  (01)  A to B     -          IO.SYS      
>  (02)  C          -          IO.SYS      
>  (03)  D          -          MODISKP.SYS 
>------------------------------------------------
>For more information, type 'chkdd /d' in the directory containing chkdd.com.


9.3 MO media trouble
-------------------
(1) Is the media physically formatted ?

    In order to know whether the media is physically formatted, run FJFDISKJ.
    If the media is not physically formatted, FJFDISKJ displays message,
    "Low-level format is needed".
    Then continue to execute low-level format.

(2) Is the media logically formatted ?

    In order to know whether the media is logically formatted, run FJFDISKJ.
    FJFDISKJ shows the mark "*" in front of the format type in which the 
    media is formatted now.
    If the media is not logically formatted, no "*" will appear.
    Then continue to execute logical format.





APPENDICES
===========

APPENDIX A: Why is the device driver necessary?
===============================================
If the port connected to M2541B is supported by BIOS, the DOS internal 
disk driver (IO.SYS) assigns a logical drive letter (drive D:, for example) 
to M2541B. 
Data can be written to and read from the MO disk through drive letter D:.

If, however, the MO disk is ejected and another MO disk is inserted, 
the system cannot logically access the new disk. 
This is because DOS internal disk driver does not support the change of 
the disks. 
Sometimes it may seem that accessing is successful, but the directory 
tree known to DOS as internal data conflicts with the actual directory 
tree on the disk. 
Therefore, the files may be destroyed if the disk is used for a 
continued period. 
When using M2541B by the drive letter assigned by the DOS internal disk 
driver, NEVER change the disks.

The device driver is necessary for using M2541B as a removable disk drive.
When the drive is accessed via the device driver, the device driver 
notifies to DOS of the disk change. 
This ensures that the internal data of the OS matches the directory tree 
on the disk.


APPENDIX B: Why is KILLDRV necessary?
=====================================
B.1  Outline
------------
If the port connected to M2541B is supported by BIOS and an AT-HDD format 
disk is inserted upon starting the computer, DOS internal disk driver(IO.SYS) 
assigns a logical drive letter (drive D:, for example) to M2541B. 
The device driver, on the other hand, assigns a different logical drive 
letter (drive E:, for example) to M2541B.

In such a case, M2541B can be accessed both by drive letters D: and by E:. 
This may result in destruction of files. (DOS assumes that D: and E: are 
physically different drives.) 
To solve this problem, KILLDRV disables the drive letter assigned by 
the system. 
In the above case, drive D: cannot be accessed when KILLDRV is performed. 
Once KILLDRV is executed during the boot process of the computer, 
it is effective until the computer is turned off.

For example, DIR D: results in the following message:

>Invalid drive specification

[Figure]
           +----------------------+
           |   File System        |
           +----------------------+
               |              |
           +--------+     +--------+
           | IO.SYS |     |Device  |
           |        |     | Driver |
           +--------+     +--------+
            D: |              | E:
               +-----+    +---+
                     |    |
                  +----------+
                  |  M2541B  |
                  +----------+
 
                        |
                        | KILLDRV
                        V

           +----------------------+
           |   File System        |
           +----------------------+
               |              |
           +--------+     +--------+
           | IO.SYS |     |Device  |
           |        |     | Driver |
           +--------+     +--------+
            D:(invalid)       | E:
                              | 
                         +----------+
                         |  M2541B  |
                         +----------+


B.2  What if KILLDRV is neglected?
----------------------------------
The device driver itself disables the drive letter assigned by DOS 
internal disk driver. 
Even if KILLDRV is not executed, the drive letter assigned by DOS 
internal disk driver cannot be accessed. 

For example, DIR D: results in the following message:
(In the case KILLDRV in not performed.)

>Invalid media type reading drive D
>Abort, Retry, Fail? 

The control by the device driver, however, is insufficient. 
The device driver allows the following commands to be executed:
- FORMAT command of DOS
- DEFRAG command of DOS
After either command is executed, drive D: can be accessed. 
KILLDRV is used to prevent this.

  -------------------------------------------------------------------
                 KILLDRV executed              KILLDRV not executed
  -------------------------------------------------------------------
  DEFRAG D:      Not executed                  Executed
  FORMAT D:      Not executed                  Executed
  FDISK          Executed                      Executed
  -------------------------------------------------------------------
Be particularly careful of the use of the FORMAT command, 
as it erases all data on the disk.

