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6.17 Can I use both DOS and NEXTSTEP/Intel partitions on the same hard disk?

Yes. NEXTSTEP/Intel will support multiple operating systems on the same local hard disk. When the system boots, the user can chose to boot another operating system (such as DOS) or NEXTSTEP. If the local partition contains DOS, NEXTSTEP/Intel will be able to access the local DOS partition and read/write files to it, with the restriction on primary partitions only.

Executive Summary: It is possible to install DOS, Windows NT with NTFS, and NEXTSTEP/Intel on the same disk, and select which partition is booted at boot time.

I spent some time experimenting with a 200MB SCSI disk. I wanted to see if the following configuration would be possible:

Since Windows NT requires at least 70MB for installation, and NS/Intel requires at least 120MB, there wasn't much room for DOS! Ultimately, I only tested a three partition system (DOS, NTFS, NS/Intel), but I have no reason to believe that the extended DOS wouldn't also work.

The recipe is as follows:

• Preparation. You need a bootable DOS floppy that has FORMAT.COM on it. You need another (blank) floppy for installing NT.

• Start with the NS/Intel installation. When it asks you how you want to configure your disk, it gives you three choices, which are basically
  1. erase the whole disk and use it all for NS/Intel,
  2. save some room for DOS,
  3. advanced. Choose the advanced option, which places you in NS/Intel fdisk (not to be confused with DOS FDISK.EXE).
• Create three partitions in this order:
  1. Primary DOS (if more than 32MB desired, use the "large" FAT option)
  2. HPFS (this is a placeholder for NT, and can be any non-DOS format)
  3. NEXTSTEP
• Proceed with the rest of the NEXTSTEP installation.

• When NEXTSTEP is safely installed and tested out, boot DOS from your bootable DOS floppy.

• FORMAT the DOS partition (which should be Drive C if you made it the first partition). You want to FORMAT C:/S, to install the boot code to make the DOS partition bootable.

• Once DOS is safely formatted and tested out, insert the NT installation floppy and reboot.
• Proceed with the NT installation. Tell Setup to install NT in the second partition (which shows up as "Unformatted"). You can select NTFS for FAT format.

• Insert the blank floppy when asked. Don't bother to format it, NT unconditionally formats it.

• If you select NTFS, there is a scary part of the installation that makes it seem like NT can't reboot. In fact, it is converting the installed files from FAT to NTFS in place. Just let it keep rebooting until it finishes, don't interrupt it like I did.

• Finish setting up NT and test it out. It should be able to see the DOS partition in FileManager.

• Likewise, there should be a DOS filesystem in / on NS/Intel. If you configured NT for FAT instead of NTFS, there should be two DOS filesystems in /.

That's it. When you boot, you see the familiar NS/Intel boot manager. If you select DOS, it boots NT, which in turn offers you a chance to boot DOS or NT (not NS/Intel, of course). Kind of weird that you have this two tiered boot, but it's probably because the bootsector has been modified by NT. I haven't tried setting the active partition to DOS -- that might avoid the two tiers.

• (continue with 6.18 Can NEXTSTEP/Intel read, write, and format DOS and Mac floppies?)