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Dual boot XP / MS-DOS install, partition size, FAT vs NTFS

by katie alice / February 24, 2007 3:10 PM PST

I'm wiping my laptop HD and starting fresh. I want to install DOS and XP, and I've gotten a lot of tips through searching old posts, but I still have a few questions. There wasn't much out there for this particular combination.

First, equipment. I've got a Toshiba Satellite M55 with a 75 GB HD. I'm installing HP Home. I have no floppy drive. I'm also using a 250 GB USB external hard drive for backups and such.

Partitions: What size for each? I was thinking I'd have one for DOS, one for XP and applications, and one for data, although I'm planning to store most of my non-essential data on the external. Is it beneficial to also have a separate partition for the swap file? I read a recommendation in another thread for a 30 GB volume for XP/apps and a 2 GB volume for the swap file with the rest allocated for data, but I didn't find any recommendations for MS-DOS volume size.

FAT / NTFS: I know that I'll need the DOS volume to be FAT and that I'll need to install DOS first. Will the other volumes need to be FAT too, in order for anything there to be accessed by DOS? I think I'm gonna need to save video files >4GB, so that wouldn't work too well. Unless I could have a small partition formatted NTFS just for video files? Once downloaded, most of the files would probably be transferred to the external, but they'll need a temporary home on the internal. Also, it would be ok to format the internal FAT and keep the external NTFS, right? They can work together?

I don't really plan to use DOS much, mostly for emergencies. For instance [back story], next time Windows crashes and will only boot so far as the splash screen before giving me the BSOD, I'd like to have a way to operate this beast. I'd also like to be able to run programs in DOS without Windows unnecessarily hogging all the resources. I miss the option of starting in MS-DOS mode; this would all be unnecessary. I repaired the install to get myself back to partial functionality - just barely enough to copy my files - which in itself was a mess. I'm no longer able to COPY or PASTE or drag-and-drop, so I had to go into the MS-DOS prompt and XCOPY everything. From this point forward, obsessive backups.

Also, I'd like to point out that I'm the worst kind of computer user: the kind that always thinks they know what they're doing, and thus tends to screw things up much more than other people. I've done tech support; I know and hate people like me. For that, I apologize, and also if this is too long and over-explained.

So, how shall I proceed?

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by jackson dougless / February 24, 2007 10:00 PM PST

Let's start from the beginning.

1: Is there any benefit to having a dedicated swap partition?
A: No.

2: What size partitions should I use?
A: Whatever you need for the programs you want to install, and probably a little extra. How much extra depends on how much you think you'll need. Personally, I'd allot more space to XP than DOS, since DOS programs were generally very small, whereas Windows programs are ballooning in size every day.

3: Do all partitions need to be FAT?
A: No. In fact, DOS can only handle FAT12 and FAT16, and since FAT16 has a size limit of around 2GB, it won't be very useful. XP should be NTFS, and you may have to partition your external drive, creating a special 2GB FAT16 partition just for DOS.

As a bit of an aside, I don't think installing DOS is going to be such a good idea. Like I said, it can only read FAT12 (primarily used for floppies) and FAT16. This would mean you wouldn't be able to read anything from the XP partitions, unless you made a large number of 2GB FAT16 partitions.

You would probably be better off getting a Knoppix Linux CD, or some other bootable CD Linux distribution. These can be great help in dealing with a damaged operating system. The entire thing runs from the CD-ROM, something your system is all but guaranteed to be able to do. I had a 486 that could boot from the CD-ROM drive, just like every other system I've owned/built, so yours should be able to as well. At the very least, a bootable Linux CD should get you read access to your NTFS partitions, and then let you copy the files to your external, provided it's formatted as FAT32. I'm not sure on the status of NTFS write support in Linux, and more specifically, the latest Knoppix version, so it's probably best not to count on it.

Knoppix CD images are a free download from their website, and I think they sell commercially pressed discs that will last quite a bit longer than a burned CD. You could just be sure to keep this disc in a safe place until such time that it's needed.

Alternately, if you insist on going the dual boot route, you could replace DOS with Linux in your plan. You could do a minimal install, so it doesn't need a lot of disk space, and have it ever at the ready to copy files off of your Windows partition to your external. The major benefit to this method over a bootable CD, is that if your system has a CD/DVD burner, you could use that as another method of backing up files.

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by katie alice / March 2, 2007 6:54 AM PST
In reply to: Well

OK. I'm getting the idea that this was pretty much a bad idea from the beginning.

The "why" of all this to begin with is that I do not trust Windows. It's unreliable, what with the freezing and BSODs and crashing and such. [Not that that is an original observation.] This incident was the final straw. I take very good care of my laptop. I diligently keep her secure and clean, junk-free, defragged, etc. I obsessively keep my baby safe from malware. No one else touches her. When the BSOD on boot happened and wouldn't stop, I had been having zero problems and I hadn't recently screwed with anything. Recovery has barely brought her back to functionality, giving me no option but to start fresh. And I have no idea what caused the crash which makes me absolutely furious and further heightens my distrust of [and malice towards] Windows.

I desired to use DOS because it's the only other OS that I am comfortable with. I've long suspected that the time would come for me to learn Linux, and I suppose that it finally has.

I'll put my research efforts towards that endeavor and scratch the DOS plan. Thanks a ton for your help. It's saved me a lot of wasted effort.

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Re: MS-DOS & XP dual boot
by Kees Bakker / February 24, 2007 10:24 PM PST

What version of MS-DOS would you want to install? And what dual boot manager?
And the WHY would be very interesting to learn about, apart from your rather vague description. What's wrong with using the recovery console in case of emergencies like the one in your post? And what possibly good would it be to have MS-DOS then, if it doesn't even support long filenames on a FAT-32 XP partition?


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Bad idea. More...
by R. Proffitt Forum moderator / February 24, 2007 10:33 PM PST

"The use of Win95/Win98 FDISK in a mixed system is dangerous. It will delete a non-FAT logical partition when you had actually told it to delete a FAT partition somewhere farther down the chain of logical partitions. See Cannot View NTFS Logical Drive After Using FDISK."

And you want to use DOS from before that version. More reading at

By wanting to boot DOS you learn about limitations and pitfalls.

If you insist, install the OS from oldest to newest and along the way you'll get a boot menu.


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Start with an unpartitioneed and unformatted drive...
by Edward ODaniel / February 25, 2007 4:34 AM PST

now install DOS (create a less than 2 GB partition and leave the rest of the disk unallocated).

After DOS is installed install Win XP (boot and install from the CD) and install it to the unallocated portion. Size any partitions as desired, but because the boot partition tends to get heavy with patches and service packs I suggest a relatively large partition for XP. Format it as NTFS.

After installing XP you can use Disk Management to create any other partitions you may choose to have. I would format them as NTFS also.

Now, DOS will be unable to "see" anything on the NTFS volumes so you will want to locate NTFS4DOS which allows your to "see" an NTFS volume from DOS. There are several utilities available, some of which allow read only access and others that allow write access too. Here are a few to consider:

Arguably, the simplest is NtfsDOS which is explained and available here (and the readme file in the zip download explains exactly how to make use of it):

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