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Install Dual-Boot of MS-DOS 7.10 (FAT32) on Windows 7 computer (Win7 installed first)

Last reviewed: June 2013

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


This guide shows how to correctly and safely create a natural dual-boot of Windows 7 and MS-DOS 7.10 on a computer with Windows 7 already installed. You can then run either of those OSs by selecting one from a menu during bootup. No data loss will occur and a third-party boot utility is not used.

You need to shrink the Windows drive to make room for MS-DOS. While DOS 6.22 needs to be on the first physical partition of the first disk, DOS 7.10 can be on the first FAT32 Primary partition whcih can be located anywhere on the disk; non-FAT/32 partitions are ignored by DOS 7.10. Using a second disk for MS-DOS is not an option.

32 and 64-bit versions of Windows 7 Home Basic, Enterprise and Ultimate were used in testing so this will also work with Windows 7 Premium and Professional. The computers used were:
(1) 64-bit Dell Studio XPS 8100 (2.93 GHz), Core i7, 8 GB RAM DDR3, 2x1 TB SATA hard disks in RAID 0 as 1.6 TB & 60 GB
(2) 64-bit AMD Athlon (2.4GHz), 2.0 GB RAM, 1 TB SATA hard disk.
(3) 32-bit Dell Optiplex with Pentium 4 (2.26GHz), 2.0 GB RAM, 160 GB ATA hard disk

Following these instructions correctly should always succeed. However, any change to your computer should not even be considered unless you have a rescue plan. This guide also contains that rescue plan - just in case!

This procedure is suitable for experienced computer users.

Important Installation Notes

Hidden Active Partition. Many Windows 7 users will have at least one small Primary disk partition(s) that's hidden (but is visible under Disk Management in Windows 7). This must be counted if you want to create a new Primary.

ATA Mode. Many users will have a SATA hard disk and that's not a problem in itself. However these users may need to set the BIOS to ATA mode (vs AHCI) for DOS usage. This possible problem was not encountered during tests with SATA.

EasyBCD. The highly-acclaimed EasyBCD is a free editing utility that allows any user to easily edit the Windows 8/7/Vista boot menu (the BCD or Boot Configuration Data). EasyBCD runs in Windows 8, 7 and Vista, but also in Windows XP if you first install Microsoft's free .NET 2.0 Framework.

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Details: Install MS-DOS 7.10 when Windows 7 is installed first

Installing other operating systems on your Windows 7 computer may invalidate your warrantee.
It's important to follow the instructions exactly as stated and you should have a properly working Windows.

Make your preparations

  1. Backup important data before making any changes to a partition. 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)
  2. Plan your new partitions carefully before you start.
  3. Download Neosmart's EasyBCD (free - it edits Win7/Vista boot menu).
    Optional: Download NeoSmart's free Windows 7 System Recovery Disk if your Win7 DVD is missing!
  4. Disconnect all unnecessary external devices before you start.

Make free space and create new partitions

MS-DOS 7.10 must be installed on a Primary partition on the first hard disk or first RAID 0 disk.

The Windows 7 drive is shrunk leaving some Unallocated space at the end of the first hard disk (to the right). A new Primary partition is then created in Unallocated and Formatted with FAT32. If you need a fourth Primary partition, read Create a Fourth Primary partition - but remember, having four Primaries means you cannot have any further partitions on that hard disk!

The 127 GB hard disk limitation that afflicts Win98/Me/2K is not a problem with MS-DOS 7.10. Also, the Active marker is unaffected by installing MS-DOS 7.10 so Windows 7 will still continue to boot normally.

  1. Restart computer correctly (close all programs before you Restart computer).
  2. Open Disk Management in Windows 7 (right-click Computer, select Manage, click Disk Management).
    • Right-click the Win7 volume, and click Shrink Volume.
      • In Enter the amount of space to shrink in MB:, enter enough for MS-DOS.
      • Click the Shrink button (it may take some time!).
      If Shrink does not give you sufficient Unallocated space, read how to Shrink the Windows 8, 7 or Windows Vista Partition for instructions or use the free GParted Live CD. Then return here.
    • Right-click the Unallocated space and select New Simple Volume.... Click Next.
      • In Simple volume size in MB:, use all available space for MS-DOS. Click Next.
      • In File system, select FAT32 in the drop-down.
      • In Volume label, enter doos (or similar).
      • Tick to enable the Perform a quick format check box, and click Next.
      • Click Finish button.
    • Still in Disk Management, check that the change made is correct. Unfortunately Disk Management will only create Logical partitions if three Primaries already exist. If a new Primary partition has not been created, you will have to delete the Logical just created and use Win7's Diskpart command utility to Create a Fourth Primary partition in the Unallocated (RAW) space.
  3. Restart to Windows 7.

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Next Install MS-DOS 7.10 in this Windows 7 Dual-Boot

The link below shows how to install MS-DOS 710 in this dual-boot and how to use EasyBCD with it.

The Windows 7 boot menu will then boot MS-DOS 7.10 or Windows 7 when selected.

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Related Reading

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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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