IBM PC DOS 7.1

Taken from https://forums.virtualbox.org/viewtopic.php?f=4&t=80531

Get a PC-DOS 2000 boot floppy and leave just the following files:

ATTRIB.EXE
COMMAND.COM
IBMBIO.COM 
IBMDOS.COM 
FDISK.COM 
FORMAT.COM

Boot from the PC-DOS 2000 floppy and partition your drive as needed.

Make sure you 'sys' the drive using format /s

Warning: I found that formatting a FAT32 partition was not supported and had to do that on another system, though the formatted partition did actually show up fine after being created on another system.

Get a copy of the newer PC-DOS 7.1 files (they are under 1MB in total) and copy them to a floppy disk under a PCDOS71 folder.

Delete the 7.0/2000 system files (IBMBIO.COM, IBMDOS.COM, COMMAND.COM) from the formatted hard drive:

A:\>ATTRIB -S -H -R C:

A:\>DEL C:\*.*

Copy the 7.1 system files to the C: drive. //Make sure you do it in this order!//

A:\>CD PCDOS71

A:\PCDOS71>COPY IBMBIO.COM C:
        1 file(s) copied

A:\PCDOS71>COPY IBMDOS.COM C:
        1 file(s) copied

A:\PCDOS71>COPY COMMAND.COM C:
        1 file(s) copied

Create a DOS directory on C: and copy the 7.1 files into it:

A:\PCDOS71>MKDIR C:\DOS
A:\PCDOS71>COPY *.* C:\DOS
   ...
XCOPY.EXE
       43 file(s) copied

You should now have a formatted PC-DOS 7.1 partition with just the new PC-DOS 7.1 system files in C:\DOS.