Dual Boot Win98SE/MS-DOS HD Limitations

[HenriK]

This query is probably for someone with a long memory or who has been around PCs for a long time. I am assembling a dual-boot (using PowerQuest's BootMagic) Win98SE/MS-DOS 6.22 system on an unused Dell Dimension 4500 platform I had to run some old software I have and want to use that doesn't run well on XP-Pro and later operating systems.

It seemed to me that to have some file access compatibility and versatility, I needed to format the system's HD as FAT 16 as MS-DOS will not access FAT 32 disk partitions. When I went to create an extended DOS partition to put the applications and files into, I found that MS-DOS appears to want to restrict me to a maximum HD size of about 8 gB even though I have a 30 gB HD on the machine.

Is it correct that a FAT 16 HD is limited to 8 gB? Did anybody ever come up with a way to exceed that size limit? If so, where might I obtain an application (presumably unapproved by Microsoft) that would let me do that?

Thanks, in advance, for any advice, guidance, or directions to a tutorial on the subject.

[dencorso]

Welcome to MSFN!

Is it correct that a FAT 16 HD is limited to 8 gB?

If you limit your options to the 4 possible primary partitions and FAT-16, then yes. If you use 1-3 primaries and one extended partition, then no, you can have 24 partitions (C:-Z:). Now, if all of them are FAT-16, your limit would be 48 GiB...

Wikipedia is your friend: FAT, MBR, EBR, VBR and Boot Sector.

[rloew]

This query is probably for someone with a long memory or who has been around PCs for a long time. I am assembling a dual-boot (using PowerQuest's BootMagic) Win98SE/MS-DOS 6.22 system on an unused Dell Dimension 4500 platform I had to run some old software I have and want to use that doesn't run well on XP-Pro and later operating systems.

It seemed to me that to have some file access compatibility and versatility, I needed to format the system's HD as FAT 16 as MS-DOS will not access FAT 32 disk partitions. When I went to create an extended DOS partition to put the applications and files into, I found that MS-DOS appears to want to restrict me to a maximum HD size of about 8 gB even though I have a 30 gB HD on the machine.

Is it correct that a FAT 16 HD is limited to 8 gB? Did anybody ever come up with a way to exceed that size limit? If so, where might I obtain an application (presumably unapproved by Microsoft) that would let me do that?

Thanks, in advance, for any advice, guidance, or directions to a tutorial on the subject.

The 8GiB Limitation is due to the lack of LBA Support, not the FAT16 Limitation.

I wrote a Patch and Drive Overlay that remaps a larger Hard Drive into 8GB Virtual Drives. Using a fairly complex Partitioning scheme I was able to support more than 8GiB in both DOS 6.2 and Windows 98.

[dencorso]

The 8GiB Limitation is due to the lack of LBA Support, not the FAT16 Limitation.

Yeah... well, lack of LBA support hadn't crossed my mind, although it should, since we were discussing a similar case quite recently. Of course you're right, RLoew!

So, Henrik, if you want more info on RLoew's products, visit this link.

And for info on the various hardware limits to HDDs, visit this link.

[jaclaz]

I am assembling a dual-boot (using PowerQuest's BootMagic) Win98SE/MS-DOS 6.22 system ....

.... format the system's HD as FAT 16 as MS-DOS will not access FAT 32 disk partitions. ....

Please note that MS-DOS 6.22 has a number of limitations that DOS 7.x (i.e. the DOS that comes with Win9x systems) has not.

If you use 7.x you can access natively FAT32 partitions, and have LBA available.

There are very few reasons to use 6.22 instead of 7.x, but they can be set in a dual boot environment allright, and even if you actually *need* 6.22 for a few programs , you can use the 7.x for all the rest and have separate partitions.

This query is probably for someone with a long memory or who has been around PCs for a long time.

You can write the word "OLD" allright, together with white hairs we also get some tolerance to it.

(but please DO NOT use the term "Vintage computing" )

I am unaware of any DOS 6.22 compatible ONLY program that will need such a big amount of space for data, remember the common size of hard disks in the last period of times when DOS 6.22/Win 3.1x were installed on PC's "in factory" (i.e. just before Windows 95) was 300Mb.

I remember buying as "very last" DOS machines a few Compaq's that were advertised as having a 300 Mb HD but actualy had a 500 Mb one.

A *very large* "consumer" hard disk at the time was the Quantum Fireball 1 GB.

On "high end" machines (running NT 3.51 and later 4.0) I remember having large storeage in th eform of a set of a RAID with 3 2.1 GB hard disks!

jaclaz

Edited July 3, 2010 by jaclaz

[rloew]

There are very few reasons to use 6.22 instead of 7.x, but they can be set in a dual boot environment allright, and even if you actually *need* 6.22 for a few programs , you can use the 7.x for all the rest and have separate partitions.

I have an Assembler that requires DOS 6.2 and quite a few Programs Compiled by it. A few of them also require DOS 6.2.

I saw no reason to limit myself to 8GiB of shared space, per Drive, when a simple Patch made it unnecessary. The Patch has been in my Development System since the beginning of the Millennium.

In addition to being able to create the necessary custom Partition configuration, my RFDISK Partitioning Tool has a DOS 6.2 Compatable Boot Function that allows Multi-Booting DOS 6.2 and DOS 7/Windows from the same Paritition sharing all resources.

[jaclaz]

I have an Assembler that requires DOS 6.2 and quite a few Programs Compiled by it. A few of them also require DOS 6.2.

Sure , I am NOT doubting in the least *your* need for 6.22 , I am doubting the actual *need* by HenriK of BOTH 6.22 AND a high amount of space .

Just for the record AFAIK there are several ways to double boot 6.22 and 7.x, most notably MS own use of the renaming of boot files:

http://www.mdgx.com/osr2.htm#2BOOT

jaclaz

[Multibooter]

Now, if all of them are FAT-16, your limit would be 48 GiB...

I am not sure, under DOS 6.22. It's a long time ago, but I vaguely remember having run into an approximate 8GB limit under DOS 6.22. The partition layout on my old Inspiron 7500 laptops is as follows:

C= Primary FAT16, 2045.0 MB

Plus an extended partition containing:

D= Logical FAT16, 243.6MB

E= Logical FAT16, 2037.6 MB

F= Logical FAT16, 2037.6 MB

G= Logical FAT16, 1166.5 MB

H= Logical FAT32, 29.110.4 MB

I= Logical FAT32, 26.799.2 MB

no drive letter under Win98= Logical NTFS, 35.201.2 MB

Unallocated 15.828.8MB

The FAT16 partitions C thru G are together 7.530.3 MB and are visible under DOS 6.22. Logical partition H and I are accessible under DOS 7, but not under DOS 6.22. I had kept partitions D and G <2GB because if I had increased them beyond their current level, DOS 6.22 would not have seen D-G in the extended partition anymore, if I remember right. This may have been related to a 1024 cylinder limit or to a 7.9GB BIOS limit, http://tldp.org/HOWTO/Large-Disk-HOWTO-4.html

In any case, the above partition layout has worked fine for me with DOS 6.22/DOS7/Win98SE/2k/XP on a 10-year-old Dell Inspiron 7500 with Phoenix Bios v4.0 Release 6.0.

@HenriK: I like PowerQuest PartitionMagic 8, but I don't use PowerQuest's BootMagic. I had tried it years ago, but decided to stay with System Commander.

Edited July 3, 2010 by Multibooter

[dencorso]

A *very large* "consumer" hard disk at the time was the Quantum Fireball 1 GB.

I have a working 1275 MB Seagate Medalist ST31277A (manufactured in 1997) stashed more for historical reasons than because of envisioning any use for it. Your comment prompted me to take it from the shelf and test it again, it's still working and pristine!

Of course, as with all ATA-3 and older HDDs, the common PATA/USB adapter does not recognize it, so that the only way to test it is to actually connect it to a motherboard PATA controller.

Seagate Medalist 1277 (ST31277A).pdf

[M()zart]

I have a working 1275 MB Seagate Medalist ST31277A (manufactured in 1997) stashed more for historical reasons than because of envisioning any use for it. Your comment prompted me to take it from the shelf and test it again, it's still working and pristine!

Well, I have working 1,7 GB (even not GiB) Fujitsu HDD, which is still in use as my main and only HDD in my Windows 98 PC. It still works perfectly despite of quite often Reset button using.