Coexistence of DOS, Windows NT, and OS/2 2.0 On Hard Disk Drive

It has been heard to this author that many on this BBS have not been able to load DOS, Windows NT, and OS/2 2.0 on the same computer. Contrary to this, I have successfully loaded these on a 486DX33 and 386SX25 with no glitches. The trick to loading all three is to have DOS loaded first on Drive (Active Partition) C: on a sufficiently large drive to hold all the software you desire. In my case, I have been using 500+ MB Conner and 500+ Fujitsu IDE drives. 500 MB is a little large, but considering all the software one uses, at the minimum you could get by with is 200 MB but then you wouldn't have much room to do anything after DOS, Windows 3.0, Windows NT, the Win32 SDK, and OS/2 2.0 eat up all your disk space.

Nevertheless, to start with, if your system has never seen OS/2 (or its Boot manager) or Windows NT things are a lot simpler. All you have to do is clear at least 70 MB in your C: partition, use the OS/2 installation (FDISK) or DOS 5.0 Fdisk to make at least a 35 MB logical partition somewhere on your drive, and a "1 MB" "unnamed" partition the VERY END of your drive.

Next, you have to load Windows NT and Win32 SDK on the C partition and be assured that DOS and Windows NT are functional. Then all you have to do is load OS/2's Boot Manager in that "Last free 1 MB partition" on your drive and put OS/2 in the 35 MB logical partition you created earlier. What you should see is first a choice between DOS and OS/2 and then a choice between DOS and Windows NT.

If your system has seen anything but DOS you have a bit more work to do. First, back up your C: partition and any other partitions you may fear to lose (My 500 MB drives had C: to G: partitions to start). I already had a 100+MB C: partition and moved everything elsewhere except the root directory, the DOS directory, and the Windows 3.1 basic working system. Next, I booted the system with a DOS 5.0 Floppy having "Format", "Sys", and "Fdisk" at least; and then proceeded to destroy the C: partition and recreate it with Fdisk (I already had it at 100 MB so I didn't have to reconstruct the whole drive although maybe that would be the best plan). Then I also created a 1 MB non-DOS partition at the "very end" of the 100 MB G: existed and created a logical drive of 34 MB at the G: or H: position (H: would be better because when you restore the now 65 MB G: logical partition contents your paths won't get screwed up) and finally the other 65 MB logical partition with the rest. The next step was to format the G: & H: drives (the 34 MB partition formatting could wait because the OS/2 installation will take care of that but it goes fast and is probably cleaner). Now you have a "clean" area ready for installation of all three operating systems. First, you must put DOS (at a minimum) back on the C: drive and anything else you like just so you have at least 70 MB free for Windows NT and the Win32 SDK. Next step; install Windows NT + Win32 SDK and be sure they work. After this I edited the "boot.ini" to make DOS the default - it's your choice depending on where you want to end up. Then all you have to do is install OS/2 2.0 per instructions using that 1 MB free non-DOS partition for Boot Manager and put OS/2 2.0 in the 34 MB partition you created. AND wonder of wonders everything seems to hold together (at least with IDE drives - I don't know about SCSI drives).

The trick to the loading is to have a system free of all the weird things the NT loader and OS/2 Boot Manager do to things you cannot see. Once I messed up Windows NT and had to go through the whole procedure over - agony of agonies! Good Luck!