DOS utilities (MS-DOS, FreeDOS, etc.)

If you have a DOS utility such as a BIOS Flash utility or small DOS-based diagnostic .exe file, you can try using the E2B FreeDOS bootable image.
This image contains an NTFS driver and so can directly access files on a FAT32 or NTFS E2B drive.
Just make a new folder on your E2B USB drive (e.g. \MyDOS  - use a name of less than 9 characters) and copy your DOS files into it.
Then boot to E2B and go to the DOS menu and run 'FreeDOS (from a floppy image)'.
When it boots to FreeDOS, type:
cd \MyDOS  
to change to the directory and then type the name of your .exe or .com file to run it.
If your utility runs from a .bat batch file, you may need to edit it (or copy your files to the root of the E2B USB drive).
If your DOS utility reports that there is not enough memory available, you will need to create your own bootable .ima or .img floppy disk image which does not load the large NTFS driver.
You can use WinImage to add or delete files in the .img file.
See RMPrepUSB DOS tutorial here for more details and the RMPrepUSB WinImage tutorial here.
A FreeDOS v1.2 floppy disk image can be downloaded from here.

Floppy Disk Image Files

If you are provided with a bootable floppy disk image file, E2B can directly boot to it.
If you use the .IMA or .IMG file extension, the file will be loaded into memory and will boot as Drive A:
If you change any files on the A: ram-drive whilst booted to DOS, no changes will be saved.
If you want to be able to permanently change files in the image under DOS, use a .imarw file extension.
If you use a .imanousb file extension, the image will appear as A:, the USB drive as B: (and not as a hard disk).
Use .imafdhdd0 if you only want the internal hard disk as hd0 and the image file as fd0 (writable).
See the file extensions list for other possibilities.
See the RMPrepUSB tutorial for more options here.

DOS limitations

  • DOS 6 can only access <2GB partitions (FAT16).
  • DOS 7.1 or later is required to access FAT32 partitions.
  • DOS\FreeDOS cannot access NTFS partitions unless a special NTFS driver is added.
  • Files with long file names (longer than 8.3) may not be listed correctly unless you load a LFN driver. Use 8.3 conventional short filenames with no spaces.
See here for more info on limitations of versions of DOS.

Using a .imgPTN file

An easy way to make and modify your own DOS-bootable image is to create a FAT32 .imgPTN file.
This allows direct access to the DOS files without needing to make a .ima or .img file.
1. Find a suitable MS-DOS 7 or 8 or FreeDOS floppy disk image or zip file or set of DOS boot files.
2. Extract/copy the files to an empty new folder (e.g. .\MyDos) on your Windows Desktop.
3. Drag-and-drop the new folder (MyDos) onto the MPI_FAT32 Desktop shortcut (you must install the MPI Tool Kit first).
4. Copy the 38MB .imgPTN file that this makes to your E2B drives \_ISO\DOS folder.
5. Run \MAKE_THIS_DRIVE_CONTIGUOUS.cmd from the E2B drive.
6. Now either MBR-boot to E2B and select the new .imgPTN file or use \_ISO\SWITCH_E2B.exe to switch it in.
7. The E2B USB drive will now appear as a 38MB FAT32 volume. You can directly change the files on it or edit any of the files.
You can test it by using RMPrepUSB - F11 (QEMU) to boot to it (or use Virtual Box+VMUB).
To restore the E2B drive, run \e2b\SWITCH_E2B.exe - Restore E2B Partition(s), or MBR boot from the USB drive and select menu item 0.
Tip: name the file with a .imgPTNAUTO file extension to avoid the 'OK to switch' user prompt.