FAT16 partitions are not visible from DOS

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FAT16 partitions are not visible from DOS

Postby Gahhhrrrlic » 2018-4-15 @ 05:37

It was my understanding that in a DOS environment, only FAT16 volumes would be readily accessible with FAT32 being readable under certain circumstances and NTFS being completely unreadable.

From my windows environment, via disk management, I created a small FAT16 partition of 100 MB. I then used a genuine DOS 6.22 boot floppy to boot the computer into DOS. However I was unable to see the partition I made, as it had no drive letter that I could find. I went through the whole alphabet and didn't find it. DISKPART hints at being able to see the volume but I can't access it from the command prompt. Is there something I'm missing? Thanks.
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Re: FAT16 partitions are not visible from DOS

Postby TOBOR » 2018-4-15 @ 06:11

nevermind
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Re: FAT16 partitions are not visible from DOS

Postby Gahhhrrrlic » 2018-4-15 @ 06:41

?

I guess I missed the punchline.
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Re: FAT16 partitions are not visible from DOS

Postby derSammler » 2018-4-15 @ 08:01

Lots of questions: why did you use Windows to create the partition in the first place? What is the hard disk's size? Are there other partitions on that drive already? Did you try cleaning the drive completely and re-init it with MBR?
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Re: FAT16 partitions are not visible from DOS

Postby Jo22 » 2018-4-15 @ 11:54

I second that. Also "NTFS being completely unreadable" is not quite right.
There are several third party drivers that allow for this. One of them supports r/w, even.
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Re: FAT16 partitions are not visible from DOS

Postby Gahhhrrrlic » 2018-4-15 @ 15:48

derSammler wrote:Lots of questions: why did you use Windows to create the partition in the first place? What is the hard disk's size? Are there other partitions on that drive already? Did you try cleaning the drive completely and re-init it with MBR?


Sorry let me tend to some of that:

I may not have known the reason precisely but I wanted all my drive letters nice and neat in each OS, and I thought that if I made the volume from dos, it would get all messed up when I went back into windows to see it. I figured disk manager was the only way to set everything up nice and neat. Also, since DOS can only 'see' so much of the hard drive,I was also worried it may put the partition in some stupid location on the platter or in such a way as to split up the rest of my partitions badly.

Disk 0 = 250 GB SATA @ 7200
Disk 1 = 600 GB SATA @ 10k

Disk 0 has XP + 3 more partitions (D,E,F) including the FAT16 at the end
Disk 1 has Win7 + 5 more partitions (D, E, F, G, H) including the FAT16 at the end (it has its own FAT16)

Don't understand the last question. Both drives were brand spanking new and factory formatted when I first used them. I started with only a C drive on each just to get the OS's running and later after both were good I added everything else.
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Re: FAT16 partitions are not visible from DOS

Postby Gahhhrrrlic » 2018-4-15 @ 15:50

Jo22 wrote:I second that. Also "NTFS being completely unreadable" is not quite right.
There are several third party drivers that allow for this. One of them supports r/w, even.


I think I know what you're talking about, as I have the demo boot disk for it. Something called NTFSread maybe? I can't remember. I just remember that it worked once and then I could never get it to boot up properly without an error. It seemed flaky. If you know of a util that works though, I'd love to know about it. I'll try to dig up the one I was thinking of.
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Re: FAT16 partitions are not visible from DOS

Postby dr_st » 2018-4-15 @ 17:42

DOS 6.22 will not see any extended partitions with a total size over ~5.8GB, as far as I know. Extended partition = everything that's not the primary partition (including all the logical volumes). So it's clear why it won't see any of the volumes you created.

I don't know what will happen if you create a separate extended partition and within it a separate logical FAT16 volume. Neither can I recommend a partitioning utility that can do this for you, but it may be possible.
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Re: FAT16 partitions are not visible from DOS

Postby Gahhhrrrlic » 2018-4-16 @ 05:11

dr_st wrote:DOS 6.22 will not see any extended partitions with a total size over ~5.8GB, as far as I know. Extended partition = everything that's not the primary partition (including all the logical volumes). So it's clear why it won't see any of the volumes you created.

I don't know what will happen if you create a separate extended partition and within it a separate logical FAT16 volume. Neither can I recommend a partitioning utility that can do this for you, but it may be possible.



I just checked. Since I created 2 FAT16 partitions, one for each OS, 1 of them just happens to be primary while the other is merely a logical drive on an extended partition. So should I not be able to at least see the 1 primary? The primary FAT16 is on DISK1 not DISK0 so could it be that the second hard drive isn't being polled or that the size of the drive is preventing that portion that holds the FAT16 partition from being seen?
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Re: FAT16 partitions are not visible from DOS

Postby dr_st » 2018-4-16 @ 07:02

DOS may additionally require that the primary partition is at the start of the drive. I seem to remember something along these lines, but have no conclusive evidence. Back when I used DOS 6.22 I never had a drive larger than 8GB and always put the primary partition first (using DOS's FDISK).
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Re: FAT16 partitions are not visible from DOS

Postby konc » 2018-4-16 @ 08:28

Are you sure that you cannot see the partition? Could it be that it doesn't have a drive letter assigned since it was created from windows, but is visible if you run fdisk?
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Re: FAT16 partitions are not visible from DOS

Postby Gahhhrrrlic » 2018-4-17 @ 03:46

Well I could be doing it wrong I suppose but I couldn't see it.

I went to bootdisk.com and got the 6.22 boot floppy, put it in my machine, got the C prompt and tried every letter to no avail. Fdisk shows nonsense that I can't make heads or tails of but nothing that looks like 2 110 MB partitions. I did make them in windows from the manager and 1 of them was primary with a letter so... I'm at a loss. Maybe I should just differ to what the correct procedure ought to be and try that?
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Re: FAT16 partitions are not visible from DOS

Postby Dhigan » 2018-6-12 @ 19:49

If you try this link https://www.computerhope.com/sfdisk4.htm you have a detailed step by step procedure.
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Re: FAT16 partitions are not visible from DOS

Postby yawetaG » 2018-6-13 @ 06:36

Dhigan wrote:If you try this link https://www.computerhope.com/sfdisk4.htm you have a detailed step by step procedure.


That is just the usual set of instructions. It's quite possible that DOS 6.22 Fdisk has a maximum hard disk size limit that is lower than the (for that time) impossibly large hard disks that the OP used. If Fdisk can't make sense of the drive parameters provided by the BIOS, then none of the information it presents will be correct.

Also, second that the FAT16 partitions should be at the start of the drive (and no larger than 2 GB/partition).
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Re: FAT16 partitions are not visible from DOS

Postby tayyare » 2018-6-13 @ 07:50

yawetaG wrote:
Dhigan wrote:If you try this link https://www.computerhope.com/sfdisk4.htm you have a detailed step by step procedure.


That is just the usual set of instructions. It's quite possible that DOS 6.22 Fdisk has a maximum hard disk size limit that is lower than the (for that time) impossibly large hard disks that the OP used. If Fdisk can't make sense of the drive parameters provided by the BIOS, then none of the information it presents will be correct.

Also, second that the FAT16 partitions should be at the start of the drive (and no larger than 2 GB/partition).


Exactly. All of the FAT16 partititons must be (AFAIK) in the first 8GB of the HDD and must have 2GB size maximum each.

MS-DOS 6.22 FDISK is flawed when it comes to large HDDs, and If I remember correctly, so are Windows 95 and Windows 98/SE FDISKs. Try to find and use a free third party utility, or patched FDISK. This page has fixed versions of FDISK and FORMAT utilities:

http://www.mdgx.com/upd98me.php I haven't tried them, so I'm not personally sure how accurately they work. If you are ok with primary partititons only (which I almost always do, up to four is allowed under normal conditions), You can use EFDISK from Masterbooter package (shareware but fully functional where it counts)
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