Hello.

Regardless of which DDO you will be trying, MS-DOS 6.22 can't see more than 8 GB per HDD and it is limited to 2 GB per FAT16 partition.

I think the same.

While it's technically possible to patch MS-DOS 5 and 6 to break the 2GB barrier per partition, it's barely useful in practice.
It will cause trouble with various DOS utilities, too.

Really, MS-DOS 7.1 is a better solution here.
It not only is LBA aware, but can handle a few hundred GBs via FAT32.

The plain Windows 3.1x works fine with MS-DOS 7, also, as long as it uses a temporary swap file for virtual memory.
Then, it will use DOS to access that file. No manipulation on file system basis is done by Windows then. DOS is doing everything.

It's merely Windows for Workgroups who's having big trouble with MS-DOS 7, I think.
Because it uses VFAT and has virtual FAT helper driver that gets confused.
Here, a patch is needed to make it work with MS-DOS 7.1.

Also worth a trying out is IBM DOS, by the way.
IBM DOS 7 or IBM DOS 2000.
The latest version supported FAT32, even.
IBM DOS is very compatible to MS-DOS and Windows 3.x, in general.

Jo22 wrote on 2024-06-18, 20:46:

I think the same.

While it's technically possible to patch MS-DOS 5 and 6 to break the 2GB barrier per partition, it's barely useful in practice.
It will cause trouble with various DOS utilities, too.

You simply have to create a 4GB partition using a proper tool and format it fat16 using said tool. Ranish can do that.
And it's what I did for my games partitions. But yeah, other than the games partition I think it's not useful (clusters are kinda big).

No need to patch msdos.

Thus, msdos 7 with fat32 might be a better option.

Rav wrote on 2024-06-19, 04:26:

No need to patch msdos.

Hi, I didn't mean FAT16B limits. Windows NT3/NT4 can handle this, too.

What I was referring to was this:
Re: Browsing a harddisk under DOS without using BIOS routines (INT13H)

MS-DOS 5 and up do almost support larger HDDs, if it wasn't for that infamous 1024 cylinder limit and the limits of the int13h BIOS interface.

The normal one, not the extended ("INT13h Extensions"). Most modern BIOSes do limit the values for sake of compatibility.

Virtual PC 2004/2007 is an positive exception, though. It works like an early 90s BIOS here and allows this hackery.

After applying the patch, MS-DOS can format almost 4 GB.
Picture: Re: Intel VS440FX refuses to boot DOS 6.22 from detected SSD

Anyway, the practical use is limited. Without adapting the default cluster size, there's little to gain with FAT16B past 2GB.

Except if a few, large files are being stored, I suppose.
Or if a drive compression like SmartDrive was being used (=one big, fixed file). Or a swap file.

Edit: The limits of BIOS and normal int13h are being described here:
https://www.win.tue.nl/~aeb/linux/Large-Disk-4.html

That being said, I suppose your method involves increasing the amounts of heads without touching the 1024 cylinder limit?
If so, that's also a way. I just wonder if a patched MS-DOS 5 or 6 could overcome the ~8.5 GB limit. If it handles >1024 cyl, 256 heads, 63 sec I mean.

Edit: Never mind. I made a mistake here. We're already at 2GB here. I forgot about 504 MB limit.

Edit: Btw, there's a trick to use old disk utilities such as Defrag or PC-Tools' Compress on MS-DOS 7.
The command is "LOCK" and not well documented. Old utilities should be used on a FAT12/16 partition only, though.

Rav wrote on 2024-06-19, 04:26:

You simply have to create a 4GB partition using a proper tool and format it fat16 using said tool. Ranish can do that.

That requires using 128 sectors per cluster (64KB clusters) which is non-standard, 64 sectors per cluster (32KB) is the proper limit due to some tools treating the value as a signed byte instead of unsigned, or expecting the size of a cluster to fit in a 16-bit integer (usually manifested by calculating the free space as 0 bytes).

There are ways around the partition limit, for example using MSDOS redirector functionality (same as how MSCDEX or mounting network volumes works) can technically let you mount a filesystem of any type using a TSR.

jmarsh wrote on 2024-06-19, 05:23:

Rav wrote on 2024-06-19, 04:26:

You simply have to create a 4GB partition using a proper tool and format it fat16 using said tool. Ranish can do that.

That requires using 128 sectors per cluster (64KB clusters) which is non-standard, 64 sectors per cluster (32KB) is the proper limit due to some tools treating the value as a signed byte instead of unsigned, or expecting the size of a cluster to fit in a 16-bit integer (usually manifested by calculating the free space as 0 bytes).

There are ways around the partition limit, for example using MSDOS redirector functionality (same as how MSCDEX or mounting network volumes works) can technically let you mount a filesystem of any type using a TSR.

Yeah, I did encounter the issue about tools that treat the value as a signed number, I get a lot of issue with games installer that don't install because I have "negative amount" of MB available on the partition. When that append, I install somewhere and move the installation to the big partition. Lot of games have bigger files than average, it's why I consider that the only use-case. The games themself don't have issue, so far.

jmarsh wrote on 2024-06-19, 05:23:

There are ways around the partition limit, for example using MSDOS redirector functionality (same as how MSCDEX or mounting network volumes works) can technically let you mount a filesystem of any type using a TSR.

Yes, I think I've seen a few TSRs for HPFS/NTFS..

DOS 4 had a real IFS for a short moment, before it had been removed.
The normal DOS 4, I mean. Not multi-tasking DOS from mid-80s.

douglasfir wrote on 2024-06-18, 18:50:

[...] All of the overlays i'm finding seem to be geared towards a specific brand of drive.

Can anyone please help me? thanks!

EZ-Drive 9.09W and Ontrack Disk Manager 9.57 located on vogonsdrivers can be used with all drives/cf/whatever: http://vogonsdrivers.com/index.php?catid=19&menustate=68,66
give EZ-Drive a go and if that fails try ontrack

ezdrive 9.06 works fine

I have two 128GB hdd on a 486 without issues, dos 7.1, windows 3.1