MS-DOS 7.1 will not detect FAT(16?)/FAT32 partitions

[Terrum]

I recently acquired a 6.4GB hard-drive which I installed Windows 98 onto (it partitioned 503mb of the space into a FAT partition). I decided to try dual-boot Windows 3.11 on it and so far I have gotten as far as using Win3xStart and it works pretty well, with the odd glitch here and there that I can put up with.

I took the hard-drive out and used a partitioner (MiniTool Partition Wizard Free, to be precise), to partition the rest of the drive into 4GB partitions (making it 503MB, 3.99GB and 1.73GB in total). At first I partitioned it to FAT(16?) to no avail and then tried FAT32 which was also to no avail. Notably, Windows 98 detects the partitions fine, but DOS nor Windows 3.11 will detect the partitions.

Any suggestions or help that could possibly get DOS to detect these partitions? Many thanks!

FYI: I'm not too sure if FAT is FAT16 or not, hence why I am using (16?). If someone could clarify that for me that would be great!

[Darkstar]

There are many possible problems that could be the reason for this. MS DOS is still a 16 bit operating system and thus has problems with partitions that lie beyond the 2GB limit. Also, it uses CHS geometry in the partition table instead of LBA, and as soon as you have over 64(?) heads and/or 1024(?) cylinders that information no longer fits into the c/h/s spaces of the partition table and is thus left blank. Even if it does use LBA adressing (I'm not sure there, I stopped using MS DOS at version 6.2), it still has to call the BIOS to read the blocks from the disk and that BIOS is definitely 16bit.

You probably need a small driver or tool that came (on a floppy) with most larger harddisks back in the day, which provides harddisk access via 32bit routines to MS DOS. I can't remember the names of these tools from the top of my head though...

[Goldfish64]

MS-DOS 6.22 detects up to 8 GB hard drives. I used to have a 4 GB (replaced by an 80 GB) HDD and fdisk could see the whole drive but you can only create a partition up to 2 GB and format with FAT16 only.

Another important factor is the age of the BIOS and the computer. How old is it? My system's (Award) BIOS is dated 1998 and can't recognize disks above 8 GB, thus requiring a drive overlay to be installed to support the 80 GB drive that hosts DOS 6.22/WFW 3.11, NT4, 98SE, and 2000.

[Terrum]

Thanks a lot for both of your responses!

It's a Compaq Prolinea 575E (1996 I think?)

I don't believe I would require a DDO as the drive is only 6.4GB. Would repartitioning the partitions to 2GB each solve this then perhaps?

If you do end up remembering the name of it, Darkstar, that would be great!

Many thanks!

[Goldfish64]

Repartitioning to 2 GB partitions should work. DDO, EZ-BIOS, and other tools is what I think Darkstar is talking about. Every HDD manufacturer has a name for it: Maxtor's is MaxBlast, Seagate's is DiscWizard, etc. If you run fdisk from MS-DOS, does it show the size of the drive correctly? I imagine it would, since you said Windows 98 works fine and sees all the partitions.

[Battler]

There are many possible problems that could be the reason for this. MS DOS is still a 16 bit operating system and thus has problems with partitions that lie beyond the 2GB limit. Also, it uses CHS geometry in the partition table instead of LBA, and as soon as you have over 64(?) heads and/or 1024(?) cylinders that information no longer fits into the c/h/s spaces of the partition table and is thus left blank. Even if it does use LBA adressing (I'm not sure there, I stopped using MS DOS at version 6.2), it still has to call the BIOS to read the blocks from the disk and that BIOS is definitely 16bit.

MS-DOS supports whatever the BIOS supports. I have used Windows 98 SE's DOS successfully with my 60 GB hard disk some 10 years ago. It saw all partitions fine.

I think the poster first did wrong by attempting to format a 4 GB partition with FAT16 which is AFAIK not really support, the maximum limit being 2 GB. Maybe it *IS* possible if certain values are treated as unsigned but then behavior is going to be unpredictable, and even after converted, it might cause problems. I say delete that partition and this time create it from scratch as FAT32.

Edit: The BIOS might simply be too old. You say 503 MB was partitioned and the rest was empty. This means the BIOS only supports CHS which means only the first 504 MB will be seen, which explains why it was partitioned this way. This being the case then, there is no way to see those extra partitions on that machine.

[Terrum]

The hard-drive is indeed a Maxtor. Is MaxBlast something I can put onto a floppy or CD? I tried Googling it but I couldn't find any related downloads for it that would allow me to use on a floppy or CD.

However, fdisk does not detect the extra partitions. It doesn't detect any drives at all for that matter - it says 'error reading fixed disk' straight away when you type 'fdisk', so I have no way of even deleting the partition from the computer if I wanted to (unless I deleted the partitions it couldn't detect by taking the hard-drive out).

@Battler, doesn't really make sense to put the BIOS at fault if Windows 98 detects the partitions, but MS-DOS/Win3.11 cannot. Unless I am misunderstanding you for some reason. I will add however that trying to resize the main partition that DOS/Win98 made upon installation (the 503mb partition) will cause the computer to hang on boot, so it does sound like some sort of firmware or BIOS issue in regards to the -first- partition, but if Windows 98 can detect any further partitions, I don't see why MS-DOS/Win3.11 cannot.

I will try making 2GB partitions instead and update this thread accordingly however!

[Battler]

- Terrum: You said MS-DOS 7.1 can not detect the partitions. And that DOS is also used in Windows 98. Remember, that Windows 9x in 32-bit mode talks to the hard drive directly rather than through the BIOS, and therefore might see things the BIOS can't see. So it's entirely possible that Windows 98 in 32-bit mode sees all 6.4 GB of the drive because it talks to the drive directly, but any kind of DOS, even Windows 98's own 7.1, in real mode, only sees the first 504 MB because it talks to the drive through the BIOS.

[Goldfish64]

MaxBlast 4 can be found here. You will need a floppy disk. It also must be run from Windows 9x.

See this page for info on drive/BIOS limits. If your BIOS has a limitation, which it probably does, then a drive overlay is an option.

EDIT: Like Battler said, Windows NT, Windows 9x and newer use their own hard disk drivers to access the disk, not the BIOS. Even though my BIOS doesn't support drives over 8 GB, NT4, 98SE, and 2000 see the whole 80 GB just fine.

[Terrum]

Great, thanks a lot both! I will definitely look into trying MaxBlast and seeing if I can use a DDO - glad I'm not stuck in the mud at the very least. I'll update the thread tomorrow or ASAP with anything else I can. Many thanks once more!

[Terrum]

Just to add, does MaxBlast 4 give the ability to enable/create a DDO?

[Goldfish64]

Just to add, does MaxBlast 4 give the ability to enable/create a DDO?

When you prepare the disk and create partitions, MaxBlast will add DDO to the MBR if it detects it is needed.

[os2fan2]

If I recall correctly, MS-DOS 7,1 is quite capable of seeing a large partition, since it does not have to be in a special boot block. When Windows loads vfat etc, these take over the structures that DOS could already access. The main difference is that the INT 21 FN 73 LFN file name access lives in vfat32.386, which is not present when DOS boots by itself. But DOS 7.1+ understands fat32 without windows loaded.

OS/2 2.1+ and NT loads its own bios which got around the 504 M limit, but it needed to boot inside this limit. The difference is that the OS/2 install could be split over and under the 504 barrier (on two different drives), while NT had to be on one drive, and hence under the 504 limit.

[Darkstar]

If I recall correctly, MS-DOS 7,1 is quite capable of seeing a large partition, since it does not have to be in a special boot block. When Windows loads vfat etc, these take over the structures that DOS could already access. The main difference is that the INT 21 FN 73 LFN file name access lives in vfat32.386, which is not present when DOS boots by itself. But DOS 7.1+ understands fat32 without windows loaded.

OS/2 2.1+ and NT loads its own bios which got around the 504 M limit, but it needed to boot inside this limit. The difference is that the OS/2 install could be split over and under the 504 barrier (on two different drives), while NT had to be on one drive, and hence under the 504 limit.

Some corrections to your post as I think you meant the right thing, but what you wrote is wrong

DOS is never "in a (special) boot block". The boot sector is what loads DOS, but DOS resides in IO.SYS, MSDOS.SYS and COMMAND.COM, among other files, not the boot sector.

You're right in that Windows "takes over" some structures from DOS but LFN access (int 0x21, ah=0x73) does have nothing to do with LBA/CHS access, or access >2g. Windows 95 (and Windows 3.11 as well, when 32 bit disk access is enabled) loads its own 32bit drivers and completely bypasses DOS/BIOS, thus being able to access disks or partitions that pure MS DOS can't. That is, unless you load a "legacy" driver in your config.sys or autoexec.bat that keeps Windows from activating its 32bit disk access support, in which case you would have the same problems under Windows as well (i.e. you couldn't access anything beyond 504mb/2gb/8gb, depending on which of the multiple limits you're hitting)

Also, OS/2 and NT don't "load their own BIOS", they simply ignore it. They have 32bit drivers just like windows 3.11, the difference is that OS/2 or NT can't just fall back to 16bit (like Windows 3.1 and 9x can) so the problems the OP reported are usually not seen there...

[os2fan2]

I come from a time when computers did not have file systems, and output was to paper tape. It still colours my thinking.

When you boot a cdrom, or boot Novell Netware, DOS is in a separate partition, which might be discarded (as in netware). Netware has a very unix-like structure, where the /boot partition is a separate area containing DR-DOS. This is one of the reasons that Novell bought DR-DOS. The fact that DOS is not installed in a separate partition or block, means that DOS 7 understands fat32.

OS/2 has a whole mob of .bio files, largely to replace the system BIOS. Proggies still make bios calls, but this is answered by code that has displaced the system bios. This is why, for example, both OS/2 and NT can circumvent the 504 limit.

LFN has nothing to do with LBA access. DOS 7.1 knows about LBA but not LFN. There's some interesting comments in PC-DOS 7's noint25.com about disabling some INT calls to allow Windows 98's fdisk to run in place of IBM's fdisk32. There are features in DOS 7.1's command.com and xcopy which it is not clear whether these come from cruel coding on Microsoft's code, or are part of Windows that DOS accesses. I could test this in my Windows 3.1 box.

Windows and OS/2 don't "ignore" BIOS. They still load have to answer BIOS calls, so they load their own drivers for this. This could be a variety of drivers, like microsoft's HAL files, or the OS/2 .bio files that populate disk0.

[Terrum]

Just to add, does MaxBlast 4 give the ability to enable/create a DDO?

When you prepare the disk and create partitions, MaxBlast will add DDO to the MBR if it detects it is needed.

Thanks a lot for that Goldfish64. I gave it a try today and upon booting onto the diskette it said about it being recommended that I use the Windows version of MaxBlast instead of the bootable diskette version. Do you know where I can find this or if you can provide it? Many thanks!

[Goldfish64]

I gave it a try today and upon booting onto the diskette it said about it being recommended that I use the Windows version of MaxBlast instead of the bootable diskette version. Do you know where I can find this or if you can provide it? Many thanks!

MaxBlast for Windows can be found on the same site, but you should use the floppy version as the Windows version is only for upgrading to a bigger hard drive with an existing system, not setting up a new one. You will want to use the MaxBlast floppy and erase the disk. You can then set up partitions from within MaxBlast and install the OSes.

[Terrum]

I gave it a try today and upon booting onto the diskette it said about it being recommended that I use the Windows version of MaxBlast instead of the bootable diskette version. Do you know where I can find this or if you can provide it? Many thanks!

MaxBlast for Windows can be found on the same site, but you should use the floppy version as the Windows version is only for upgrading to a bigger hard drive with an existing system, not setting up a new one. You will want to use the MaxBlast floppy and erase the disk. You can then set up partitions from within MaxBlast and install the OSes.

Alright, so I'll stick with the diskette version.

So far I have tried the following:

- Tried booting into the diskette and it immediately says about setting up a hard-disk which was named 'BIOS disk 237MB', which I hit 'No' to (I presume this is the VDisk or something that shouldn't be setup by the MaxBlast software?). I hit 'Set Up Your Hard Disk' and selected the Maxtor hard-drive I have installed, selected the lowest OS it could provide (which was Windows 98SE, doesn't seem to have a DOS or Windows 3.11 selection) and it then formatted the drive in FAT 32, with a 4KB cluster size and 1 partition with all disk space. Problem now is I can't install DOS to run the Windows 98 setup as it requires me to format the drive through DOS (even though FDISK detects it

- Tried setting the jumpers to J46 and J50 as described here http://pbclub.pwcsite.com/PBInfo/PB%20I ... t4.asp.htm (which, as I can understand, sets it to master and 4092 cylinder limitation) then tried copying over my backup of the Windows 98 and Windows 3.11 setup I made before formatting, but then when booting it says 'Disk I/O Error - please boot onto a diskette'. (The jumpers were also set to this when attempting the previous procedure above)

It doesn't ask about installing a DDO or anything - I can install a DDO to a floppy, apparently, but this would not really suffice as far as I'm concerned. Overall the MaxBlast software only seems to offer FAT32 partitioning which makes it useless for DOS (as already explained, DOS will not install without having the drive properly formatted), therefore making me stuck.

Any further ideas or suggestions, or anything else that I need to possibly mention? Many thanks

[Goldfish64]

If you select Custom partitioning or something like that, you can set up multiple partitions and format as FAT16 if needed. Select Windows 98SE as an OS. When a DDO is installed, you will see the big blue banner when the system starts from the hard disk:


I would remove the jumper for the 4092 cylinder limitation and if it doesn't work, put it back. When you go to install an OS, make sure to boot from the media after the blue banner has appeared.

[Terrum]

If you select Custom partitioning or something like that, you can set up multiple partitions and format as FAT16 if needed. Select Windows 98SE as an OS. When a DDO is installed, you will see the big blue banner when the system starts from the hard disk:


I would remove the jumper for the 4092 cylinder limitation and if it doesn't work, put it back. When you go to install an OS, make sure to boot from the media after the blue banner has appeared.

Thanks for that.

What I have done now is taken out the jumper, and ran the MaxBlast diskette again and this time set custom partitions. I set 3 FAT16 partitions (1GB, 2x 2GB) for the meantime. DOS now says about it not finding valid partitions. However it can detect the first partition when using 'dir' on C: (or it at least shows that the disk has 1GB space on such drive with typing 'dir'), but fdisk says 'Error reading fixed disk' again.

I stuck the CD in for Windows 98 anyway and it now ScanDisk warns me about it not being able to read the last cluster of the drive, and that it may need to have LBA enabled. Any input on this and whether this should be done or not? And if so, how would I do it? The Compaq Computer Setup (BIOS) is really basic and doesn't have anything about LBA on it.

Any other advice including the information reported above would be greatly appreciated as always! Many thanks

Unfortunately I attempted to add screenshots with the Image Uploader but when copying the BBcode after uploading it says 'It was not possible to determine the dimensions of the image. Please verify that the URL you entered is correct.'

[Goldfish64]

First you need to check if your BIOS recognizes the full capacity of the disk. If there is a summary screen option, turn that on. As you can see in the first image below, my system can only recognize up to 8 GB HDDs, not 80 GB, thus requiring a DDO. If yours sees the whole 6000 or so MB, you don't need a DDO. Also check the BIOS for disk settings (third image). In my system it is under Standard CMOS Setup (second image).


Check the setting under something like "Mode" and tell me what it is. I am guessing that system doesn't support LBA, but if it does, that would be where it is. Also make sure the BIOS is up to date (I looked on the HP website and it looks like the newest version only adds Y2K support).

[Battler]

What I have done now is taken out the jumper, and ran the MaxBlast diskette again and this time set custom partitions. I set 3 FAT16 partitions (1GB, 2x 2GB) for the meantime. DOS now says about it not finding valid partitions. However it can detect the first partition when using 'dir' on C: (or it at least shows that the disk has 1GB space on such drive with typing 'dir'), but fdisk says 'Error reading fixed disk' again.

I stuck the CD in for Windows 98 anyway and it now ScanDisk warns me about it not being able to read the last cluster of the drive, and that it may need to have LBA enabled. Any input on this and whether this should be done or not? And if so, how would I do it? The Compaq Computer Setup (BIOS) is really basic and doesn't have anything about LBA on it.

Any other advice including the information reported above would be greatly appreciated as always! Many thanks

This unfortunately confirms your BIOS is limited to 504 MB drives because it only supports CHS.

[Terrum]

What I have done now is taken out the jumper, and ran the MaxBlast diskette again and this time set custom partitions. I set 3 FAT16 partitions (1GB, 2x 2GB) for the meantime. DOS now says about it not finding valid partitions. However it can detect the first partition when using 'dir' on C: (or it at least shows that the disk has 1GB space on such drive with typing 'dir'), but fdisk says 'Error reading fixed disk' again.

I stuck the CD in for Windows 98 anyway and it now ScanDisk warns me about it not being able to read the last cluster of the drive, and that it may need to have LBA enabled. Any input on this and whether this should be done or not? And if so, how would I do it? The Compaq Computer Setup (BIOS) is really basic and doesn't have anything about LBA on it.

Any other advice including the information reported above would be greatly appreciated as always! Many thanks

This unfortunately confirms your BIOS is limited to 504 MB drives because it only supports CHS.

Apologies for the delay in response lately as I've been pretty busy.

In response to the quote above and Godlfish64's post, I can't find any extra settings or 'summary' in the BIOS. The Compaq's BIOS is unfortunately incredibly basic. If it only supports CHS, will it not support a DDO?

[mallard]

In response to the quote above and Godlfish64's post, I can't find any extra settings or 'summary' in the BIOS. The Compaq's BIOS is unfortunately incredibly basic. If it only supports CHS, will it not support a DDO?

The BIOS provides a device-independent API for accessing data stored on disks (the INT 13h interface), which is used by DOS, Windows < 3.11*, most bootloaders, etc. A DDO works by replacing the INT 13h handler with its own code, which replaces the BIOS functionality for hard drives (and usually just forwards calls for floppy drives to the original BIOS handler), so yes, it will work even if your BIOS only supports CHS, as long as the hardware is supported by the DDO (i.e. it's a standard IDE controller and, in the case of OEM provided DDO software, the drive vendor matches).

* Windows 3.11 introduced "32-bit disk access" which accesses the hardware directly, bypassing the BIOS, however, the IDE driver provided by Microsoft is very paranoid and refuses to work unless the BIOS and the hardware agree about the disk geometry, so a DDO (or a modified driver) will still be needed for large disks.

[Terrum]

In response to the quote above and Godlfish64's post, I can't find any extra settings or 'summary' in the BIOS. The Compaq's BIOS is unfortunately incredibly basic. If it only supports CHS, will it not support a DDO?

The BIOS provides a device-independent API for accessing data stored on disks (the INT 13h interface), which is used by DOS, Windows < 3.11*, most bootloaders, etc. A DDO works by replacing the INT 13h handler with its own code, which replaces the BIOS functionality for hard drives (and usually just forwards calls for floppy drives to the original BIOS handler), so yes, it will work even if your BIOS only supports CHS, as long as the hardware is supported by the DDO (i.e. it's a standard IDE controller and, in the case of OEM provided DDO software, the drive vendor matches).

* Windows 3.11 introduced "32-bit disk access" which accesses the hardware directly, bypassing the BIOS, however, the IDE driver provided by Microsoft is very paranoid and refuses to work unless the BIOS and the hardware agree about the disk geometry, so a DDO (or a modified driver) will still be needed for large disks.

Thanks for that. Only problem is I can't seem to get MaxBlast to setup, detect or even suggest a DDO - is there any way I can set one up manually?