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First post, by lowlytech

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I have an IBM pentium machine (believe its a pc340) and I am having an issue with FDISK with dos 6.22. I have a quantum 8.4 IDE drive installed and the BIOS shows it correctly, but when I go to FDISK the drive it only shows 16MB total space. Thinking I could try the FDISK from WIN95A and keep FAT16 I fired up the system with a bootdisk and indeed WIN95 FDISK can see all the space and subsequently create a 2.1GB partition and extended for the remaining space, however when I go boot back to DOS 6.22 I get Non-DOS partitions for my FAT16 partitions. This same 16MB phenomenon happens with the WIN95 FDISK if I issue the /X switch so it's something with LBA? Not really sure if there is a fix for this issue as I really wanted to use DOS 6.22 instead of 7.x. Anyone have any experience with this? I have checked and did flash the BIOS to the newest version that I could find that is dated 1999.

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Reply 3 of 15, by lowlytech

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The geometry is my main issue with this BIOS as there is no raw values to modify, it is just hard set to auto detect. It doesn't even show the values in the BIOS, only the size. I will see if there is some utility that can verify the CHS for me. Speaking of this subject can MHDD or something similar change the values the drive reports?

I just tried the DOS 6.22 FDISK /MBR and rebooted. Still shows as Non-DOS partitions so it didn't have any effect.

Reply 4 of 15, by Jo22

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DOS 7.x is already LBA-aware, perhaps that's why it's working there (ie. it doesn't rely on original in13h).
https://en.wikipedia.org/wiki/DOS_7

I would try to use another computer for formatting/partitioning.
If you're lucky, then this computer will autodetect that drive geometry.

Btw, there's an interesting article about that DOS command. 😀
http://thestarman.pcministry.com/asm/mbr/FDISK.htm#MBR

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Reply 5 of 15, by Deksor

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I've got that computer and I never experienced that (there is only windows 95 on it though and my hdd is 1,2 GB)

However I remember a HDD that I couldn't reformat properly with FDISK (it told me that there was partitions in the expanded one but when I looked inside, there was none so I was stuck) and so I had to take a Gparted live cd to wipe everything and then properly make new partitions. What I mean is that there might be some leftovers from previous installations that weren't deleted

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Reply 6 of 15, by Jo22

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GParted is good, but the newer versions do have limited FAT support.
https://forums.opensuse.org/showthread.php/46 … FAT16-and-FAt32!

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 7 of 15, by tayyare

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I will suggest you make the partitions and format them (with /S option for the boot drive) using a W98 or W95 boot floppy. Then try and see if it boots correctly from your boot partition (formatted with system transfer option so having w9x system files). If there are no problems at that point (i.e. successful boot), delete the system files from your boot partition, boot from your 6.22 install floppy, and try to install MS-DOS.

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Reply 8 of 15, by Deksor

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Jo22 wrote:

GParted is good, but the newer versions do have limited FAT support.
https://forums.opensuse.org/showthread.php/46 … FAT16-and-FAt32!

Well my CD was burned like 10 years ago, so I don't think I'll have any problems with FAT. Plus, I just delete everything that was left on that hdd I didn't create partitions with gparted

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Reply 10 of 15, by lowlytech

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Windows 95A formats the partitions correctly and will boot, but the minute I boot 6.22 those FAT16 partitions show up as Non-DOS. However Jo22's recommended action seems to be working. I took the 8.4 drive and hooked it up to a 2005 ish dell optiplex, booted the 6.22 disk and it showed the total space correctly. It allowed me to partition the drive with 4 letters and seems to work when I hook it back to the IBM. I did have a 9.1GB drive as well that did the same 16MB issue, so it isn't the drive specifically, it is like an issue with the bios or ide controller not reporting something right. I also had a 6.4GB drive that behaved totally as expected with the DOS 6.22 fdisk/format, so it is something about maxing out the capacity that this machine gets glitchy with. So pending any corruption issues I think I am good. I am going to go ahead and write a bunch of files to the drive and see if anything strange happens. Thanks again for all your recommendations and help. It feels good when you can cross off things on your todo list.

Reply 11 of 15, by FFXIhealer

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Anecdote doesn't help you, but when I went to install Windows 95 onto a 20.4GB hard drive on an old Pentium machine, I had similar troubles getting the formatting and partition correct. I ended up using a MaxBlast Maxtor drive overlay software (because the HDD is a Maxtor drive) that - once installed - worked properly. My BIOS has an 8GB drive size limit, but I'm successfully using a 20.4GB drive in Windows and it can see all of it, so meh. Does anyone know if drive overlay software works with MSDOS 6.22?

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Reply 12 of 15, by Deksor

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@FFXIhealer : yes, I remeber using this kind of thing on my HP vectra 486 which has a limit of 504MB successfully with MS-DOS 6.22 with a 10GB HDD and also a 800MB HDD

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Reply 13 of 15, by moonlight

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I had exactly the same issue. I have a computer with a Micronics M55Hi-Plus Rev B motherboard (430HX chipset with Phoenix BIOS). The original BIOS version 4.05.10b can only recognize 4 GB HDDs. I updated the BIOS version to 4.06.13 and now it can recognize 8 GB HDDs. ( I used a 120 GB HDD but the BIOS could only recognize 8 GB) The BIOS auto-detected the HDD as 8455 MB with C=16383, H=16, S=63. LBA is enabled to support HDD size > 528 MB. This works OK with Win 9x FDISK but the FDISK in DOS 6.22 thinks it is just 16 MB. This makes it virtually useless. However I found that if I manually set the HDD parameters in BIOS with C < 16383, then FDISK in DOS 6.22 could recognize it! I started from C=8191 and gradually increased the number by adding 2^(13-n). That is, C_0=8191, C_n=C_(n-1)+2^(13-n) for the nth time. Thus the number is approaching 16383 (or 2^14-1) each time I change the BIOS setting. By experimenting with this number, I found that the maximum working number is 16351, which is only slightly smaller than the maximum number recognized by BIOS. The next number 16367 didn't work and FDISK in DOS 6.22 thought it was just 8 MB!

The root of the problem might be that the way BIOS maps the LBA to CHS is problematic when it approaches the limit. Win 9x and DOS 7 know LBA and can deal with it but DOS 6.22 only knows CHS and must rely on BIOS mapping. Anyway, this method worked for me almost perfectly. If you can manually set the HDD parameters in BIOS, you could probably try it and see if you can get a bigger usable hard drive!

Reply 14 of 15, by zyga64

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I have 4.3 GB disk in my 486 Intel Classic Ninja based PC. To use it correctly with this motherboard I had to:
- delete all partitions from it, using newer computer (clear partition table),
- on a destination 486 computer - set disk mode as Extended-CHS (LBA and CHS doesn't work here)
- create partitions using DOS 6.22 fdisk (I created two 2GB partitions because this is maximum size for FAT16)
If I created partitions using newer computer, and installed DOS on it - it can't boot on this 486.

Old Compaq computers (up to Pentium 3) used to have Bit-Shift mode as default. If you connect its disk to another PC - it cannot be booted.

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5) i865G /E5800 /2GB /Ti4200 /YMF724

Reply 15 of 15, by Cobra42898

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fdisk is known to have issues displaying free space incorrectly.

have you tried deleting the partitions, and used "25%" (or 24 if it comes out above the fat16 limit) ?

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