Multiple Systems Boot

                        Windows NT - OS/2 - DOS - Coherent

Several people have posted their methods for placing multiple operating systems 
on one machine. I have managed to put four operating systems on a single hard 
disk using four different file systems (FAT, HPFS, NTFS, AIX-2).

My method worked on two different machines with different controllers and IDE 
disks from different manufacturers. The versions of the software that I used 
were Windows NT March Beta, OS/2 2.1 March Beta, MS DOS 6.0 and Coherent 4.01.
I believe that the methods should work with other versions and other hardware 
but obviously repartitioning in non-standard ways is working without a net.

In order avoid a few traps it is important to note some differences in the four 
systems:

     DOS can only recognize two partitions, one primary and one extended
     and can only read partitions with the FAT file system but, if con-
     tiguous extended partitions are created by either OS/2 FDISK or
     Windows NT, it seems to group them together and recognize them as a
     single extended partition with multiple logical drives.

     DOS must be booted from the first partition of the first physical
     drive. Windows NT's install program requires the existence of this
     same partition with a file system that it can recognize (NTFS, HPFS,
     or FAT). DOS must be installed into this partition before installing
     Windows NT. Reformatting the C: drive or using the DOS SYS command
     after installing Windows NT will make it unable to boot Windows NT.

     Windows NT can not be booted just by making it's partition active
     unless it is installed in the C: Drive.

     Window's NT's FORMAT command can format a drive with any of three
     file systems using the /FS switch. The Windows NT setup program will
     make the C: drive active. You can use either the DOS or OS/2 FDISK
     to make another partition active. Only the Coherent FDISK will allow
     you to make no partition active (the best choice if you are using the 
     Coherent Master Boot).

     The OS/2 Master Boot uses it's own partition. Don't set any partition 
     bootable that you plan to modify later. If you do it will hopelessly
     mangle the Master Boot and you will have to reinstall it from the OS/2 
     setup.

     Coherent is limited to four partitions but will accept contiguous
     extended partitions made by other systems as being a single partition
     even if they have different file systems. Don't use Coherent's FDISK
     until all partitions for the other systems are created. It can create 
     partitions that are not completely compatible with the partitioning 
     software of the other systems.

     The Mark Williams Master Boot system that comes with Coherent writes
     to the master boot record of your hard disk. It seems pretty bug proof
     but if you want to get rid of it later, you can use DOS FDISK with the 
     undocumented switch "/MBR". This will restore your boot sector.

     Placing the FAT drives ahead of the HPFS drives and the NTFS drives
     next will keep the drive letters consistent between systems. DOS will
     see the FAT drives, OS/2 will see FAT and HPFS and Windows NT will
     see all three. Of course it would be greatly simplified if all part-
     itions were formatted FAT but that would take some of the challenge
     out of it.

     Coherent doesn't assign drive letters. It can mount drives with AIX-2
     and FAT file systems but can't share partitions with the other systems.

                                ****************

What succeeded for me was the following:

1. Partition the entire disk using OS/2's FDISK. Install the OS/2 Boot manager 
at the end of the free space and allow enough space for a Coherent partition. 
Install OS/2 in the next to last of the partitions that you have created (not 
counting the Master Boot or the free space).

2. Format the First Partition with DOS.

3. Install Windows NT in the last remaining partition.

4. Install Coherent in the free space and install the Mark Williams Master Boot 
making no partition active. Note what numbers it assigns to the various part- 
itions. They not be in the order you expected.

On bootup you will get the Mark Williams Master Boot message asking which part-
ition to boot. Entering "0" will give you the Windows NT Flexboot with a choice 
between Windows NT and DOS. Entering the number of the Coherent partition will 
boot Coherent. OS/2 must be booted by entering the number of the OS/2 Boot 
Manager and not the number of the OS/2 partition itself.

Bill Carter
Compuserve 71521,336