How to Make OS/2 and Windows 95 Coexist

There are many options available for installing Warp and Windows 95 on the same computer. This month we will look at some of them.

The transition to a system with Warp and Windows 95 has been greatly eased by IBM's Just Add OS/2 Warp utility (or try this link). This program has step by step instructions and useful tips for getting your system up and running.

There are a few general rules.

The first hinges on the copy of OS/2 you own (or plan to own). If you have Windows 95 only on a machine, and don't have a set of old Windows 3.x disks around, you will have to use the blue spine (Full-Pack) edition of Warp if you plan to run Windows 3.1 apps through OS/2 (Win-OS/2). This stems from the fact that Warp uses Windows code to handle win32s (up to version 1.15) applications. It can't currently handle Windows 95 (win32s v1.2+) programs. (Common errors from trying to run a Win95 application include: "Unexpected DOS Error: 23" and "You need a new version of Win-OS/2").

Another red flag this situation raises concerns your \WINDOWS directory. If you are currently running a Warp/Windows 3.x setup with red spine Warp, don't install Windows 95 into the \WINDOWS directory! If you do, you will have to re-install Windows 3.x (to another directory if you choose, leaving Win95 in the \WINDOWS directory) from disk and then use Selective Install to point Win-OS/2 to the new directory. A messy affair at best. Let it be noted that if you own red spine Warp you will have to have two Windows directories, one for 3.x and one for 95.

If you have a drive larger than 520 meg (cylinders greater than 1024) that your system BIOS doesn't support, and you are using some type of utility program to use all of your hard drive (such as On Track or EZ Drive) make sure the version you are using supports OS/2. To find out ask the HD manufacturer or go to their web page and see if they have a current version of the utility for your hard drive. Most makers have the utilities easily downloadable and most of the current versions support OS/2. Do this before the install; it will save you headaches.

Getting Down to It

Door #1. . .

There are two basic options for getting Warp and Win95 on the same machine. The first is a Dual Boot setup, which involves very little pain, but doesn't get you the best performance or features from Warp. Dual Boot is the default during installation, mostly because it is so simple. The only special considerations for switching back and forth between Warp and Win95 are that you have to shut Win95 down to Single Mode DOS to run the BOOT.COM program that swaps the two systems, and watching out for Win95's long filenames (there are utilities for both with Just Add OS/2 Warp). That's really all there is to it (be sure to note the above warning about your \WINDOWS directory if you are using Warp for Windows).

There are two major downfalls to installing OS/2 and Win95 this way. The first is the inherent weakness of the DOS FAT file system that Win95 still uses. On that new 1 gig+ drive each file takes up at least 16k or 16384 bytes even if the file itself is much smaller than that. This wasted space is commonly called "slack space", and you could lose up to 1/3 of your hard drives space because of it. On the other hand, OS/2's file system (HPFS) uses a set sector size of 512 bytes, regardless of the size of the hard drive. Add in the other benefits of HPFS such as built in caching, Hot Swap error correction, continuous storage of Extended Attributes, virus resistance, etc. and you begin to see why it makes such a difference. (For a detailed comparison see last month's column.)

The second downfall is that the two systems can more easily "step on each other's toes". To understand what I mean by this let's take a quick look at how Dual Boot works. In the most basic of terms, what it is doing is swapping the boot sectors between OS/2 specific start files and Win95 specific start files. Problems can occur when you last booted into OS/2 (leaving the CONFIG.SYS and other important files active), and you insert a DOS upgrade floppy disk or some other Windows specific upgrade that boots off a floppy. While not life threatening it can be a headache.

Door #2. . .

The other install option on a new machine involves playing with multiple partitions. The simplest Boot Manager install to handle both OS/2 and Windows 95 involves 3 partitions. One for Win95, one for OS/2 Warp, and a 1 meg Boot Manager Partition.

If your system is brand new, and you have all the programs included with the system on CD-ROM, the process can be fairly painless. Just choose the Custom Install selection from the Warp setup, partition your drive, and install everything (this process is very clearly explained in your OS/2 User's Guide). Let's look at it more closely on an example 1 gig HD.

If you have a way to back up the two OS/2 installation floppy disks (assuming you have the CD version), by all means do it! You never know when you are going to run into a snag with original distribution disks. It doesn't happen often but when it does it can be a major pain. Next, start the OS/2 install. When you get to the screen that asks what drive you want to install OS/2 on don't accept the C: drive; this will invoke OS/2's version of FDISK. General guidelines for a 1 gig disk are:

1. OS/2 needs at least a 100 meg partition, Windows 95 about the same. Boot Manager is always 1 meg.
2. If both systems need to get to certain data, plan ahead and make the FAT (Windows) partition a little bigger or create an extra data partition (be sure to format it FAT!!).
3. Windows 95 must be on the C: drive (first primary partition), Warp can be on any type.
4. The easiest way to split a 1 gig disk is (in the order you should create them): 500 meg Primary for Windows, 1 meg for Boot Manager, remainder for OS/2. Just remember, the OS/2 drive will not be able to be accessed from Windows (unless you use one of a few utilities floating around the net).

If you already have data on your system, the process gets a little trickier. If you have a tape drive, backing up the data first can be pretty easy. If you don't, you may want to look at one. You can get the tape drives themselves pretty cheap (about $200) and the software is easily ordered from places such as IBM Direct or Indelible Blue. Or, you may want to look at Partition Magic. It allows you to resize partitions without destroying the data already on the drive (plus it lets you convert FAT drives to HPFS without losing data).

After installing OS/2 you can now install Windows 95. You will get a few error messages when the Windows 95 install starts; don't worry, just click OK and continue. Windows 95 will disable your Boot Manager Partition (so it can run through the install correctly). To reactivate it when finished just go into FDISK from a DOS prompt under Windows 95 and set the Boot Manager partition to ACTIVE. You will now see the Boot Manager menu the next time you reboot.

Well, that's all there is to making Windows 95 and OS/2 coexist! OK, maybe that's not all there is, but with the above information you should be able to run both OS's without any problem. Of course, Windows 95 isn't smart enough to see both partitions, but OS/2 is. And when you fall in love with OS/2 you can always delete Windows 95 and get back all that wasted space.

See you next time.

note to all readers: Next month we are planning to start a readers tips section. E-mail me any tips and tell me if you want me to credit you and publish your names. You can e-mail me directly or contact the editor.

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