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Dual-Boot Windows 7 and MS-DOS 6.22
#2 by clean installing Windows 7

Last reviewed: Feb 2012

October 2013: This is the new location for this page on this site. Please update your link or bookmark.


This guide shows how to create a natural dual-boot of any version of Windows 7 (NTFS) and MS-DOS 6.22 (FAT) provided you start fresh and install Windows 7. You then run either OS by selecting one from a Windows 7 menu during bootup.
If you prefer not to clean install Windows 7 with loss of all data except your backup, then go to this page first.

In all methods MS-DOS 6.22 must be installed on the start of the first primary partition of the first hard disk

A full Windows 7 installation DVD is essential because you will execute a clean installation of Windows 7 on the 2nd/3rd partition of the first hard disk (the 1st partition is for MS-DOS 622). A Repair or Recovery disk will not work.

All versions of Windows 7 were used in testing. The computers used were:
(1) 64-bit Dell Studio XPS 8100 (2.93 GHz), Core i7, 8 GB RAM DDR3, NVIDIA GeForce GTX 460, 2x1 TB SATA hard disks
  (the two hard disks, configured as RAID 0, were replaced with a SATA 1 TB disk and then RAID Mode was changed to ATA in the BIOS).
(2) 64-bit AMD Athlon (2.4GHz), 2.0 GB RAM, 1 TB SATA hard disk (no BIOS change required).
(3) 32-bit Dell Optiplex with Pentium 4 (2.26GHz), 2.0 GB RAM, 160 GB ATA hard disk

MS-DOS internal and external commands work correctly on both 64-bit and 32-bit computers. The USB keyboard and USB laser mouse do run from MS-DOS 6.22 on a 64-bit computer. However, MS-DOS 6.22 will not run from RAID configurations. Also, MS-DOS 6.22 device drivers are not available for 64-bit hardware devices so expect those devices not to work on 64-bit computers when DOS 6.22 is running.

When testing with 600+ MB of free Conventional memory, Space Quest 3 (1993), SQ4, SQ5 and X-Com2 were installed in DOS 6.22. All ran well on both 64-bit and 32-bit computers - exactly as would be expected for 1993/5 software.

The procedure is suitable for experienced computer users.

EasyBCD version 2.0.2:
EasyBCD is a highly-acclaimed free utility that allows any user to easily enter a new OS option in the Windows 7 boot menu. The earlier 2.0 version of EasyBCD must be used as newer versions did not work in this specific situation.

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How to create a Windows 7 and MS-DOS 6.22 Dual-Boot

Installing other operating systems on your Windows 7 computer may invalidate your warrantee.
It's important to follow the instructions exactly as stated.

MS-DOS 6.22 must be installed on the first (Primary) partition of the first hard disk. It will NOT be Active!
- it's boot sector will be saved by EasyBCD in a file on the Active partition
Windows 7 must be on another Primary partition on the first hard disk. It WILL be the Active partition.

Make your preparations

  1. Locate your Windows 7 full installation DVD.
  2. Backup all important data before partitioning the hard disk. You can burn files to a CD, clone an image of your hard disk, copy files to a USB flash/pen/thumb drive, or use an USB external drive (a good choice). A poorer choice is to shrink the Win7 partition and create a Logical partition (for backup) at the end of the disk.
  3. Download a free MS-DOS 6.22 that creates a MS-DOS 6.22 bootable CD (if you don't have a floppy drive). Try AllBootDisks or or other sites. Create a bootable CD/DVD from the downloaded .ISO or .IMG file
    - in Windows 7, double-click the file, enable the Verify disk ... box, insert the CD or DVD, and click Burn.
  4. Download Neosmart's free EasyBCD 2.0.2 1343 KB to your backup location (do not use a later version).
  5. Disconnect all unnecessary external devices before you start.

Install Windows 7 and MS-DOS 6.22

During a custom Win7 installation, a first partition, not greater than 2GB, is created and then Win7 is installed on the remaining Unallocated disk space. The first partition is now formatted with FAT. The computer is booted from the DOS CD and the SYS command creates a basic MS-DOS 6.22 system on the FAT partition. A reboot still runs Win7. Finally the Active marker is switched to the FAT partition and then EasyBCD adds DOS to the Win7 boot menu. The Active marker is now switched back to the original partition. Other MS-DOS files are now added and configured as required.


  1. First remove and create partitions, and clean install Windows 7
  2. Bootup from your Windows installation 7 DVD (any version of Win7).
    Select Install Now.
    Select Custom (advanced).
    Select Drive options (advanced).
    • Highlight each existing Primary partition in turn and Delete all of them (did you backup fully?).
    • Click New and create a 1999 MB partition - no need to Format it.
    • Highlight the remaining Unallocated space and click Next (to install Win7 there).
    Reboot to Win7 when installation is complete.
  3. In Windows Explorer, right-click and Format the 1999 MB partition with FAT and label it DOOS.
    Now install a basic MS-DOS 6.22
  4. Bootup from your MS-DOS 6.22 bootable CD or floppy disk.
    • Type in and then press Enter
      SYS C:
      - you'll see a "System transferred" message on screen.
      - just in case - read below!
    • Reboot. Windows 7 will still boot normally
      - MS-DOS 6.22 is not bootable (yet) because its partition has not been made Active.

    Next copy the MS-DOS 6.22 boot sector and use it with EasyBCD
  5. Open Disk Management (right-click Computer, select Manage, click Disk Management).
    • Note which partition is now marked as Active (probably System Reserved).
      Right-click the DOOS partition and select Mark Partition as Active (click Yes for the caution).
      Minimize Disk Man. Note: You must rectify this change immediately after using EasyBCD.
    • Install and run EasyBCD 2.0.2 now.
      • Select Add New Entry in the left pane.
      • Select the Windows tab in the upper right pane.
        • In Type drop-down, select MS-DOS 6.x.
        • In Name, rename to "Microsoft MS-DOS 6.22"
        • In Drive, you'll see it is "Automatically configured". That's correct.
        • Click the Add Entry button in the same pane (click No for no Documentation).
      • Optionally, you can now modify the timeout of the boot loader menu - click the Edit Boot Menu (left pane) and set the Boot default OS after to 7 seconds and click Save Settings.
      • Exit EasyBCD.
        - EasyBCD has copied the DOS boot sector to a file on the Active drive and added DOS to Win7's boot menu.
    • In Disk Man, make Active the partition that was originally marked as Active (click Yes for the caution).
      Exit Disk Man. Reboot and select which OS to boot from the boot menu within 7 seconds
      - if you forgot to re-active the original partition, then use DOS's Fdisk (Option 2) to mark it as Active.
Finished! The rest of the MS-DOS 6.22 files must now be added to DOOS: and configured as required by each user.

Congratulations! You have created a natural dual-boot of Windows 7 and MS-DOS 6.22.
If you want to very easily add Windows 3.11 go to this page

Footnote: EasyBCD 2.0 creates an NST folder on the Windows 7 partition when it adds an operating system to the Windows 7 boot loader menu. This NST folder contains file(s) vital to booting an added OS. It must not be deleted.

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Please remember that you alone are responsible for the consequences of any changes you make to your computer hardware or software.

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