32MB was the DOS 3.x maximum partition size. In DOS 3.3, just create multiple extended partitions. The software probably was just a partitioning tool, in case they didn't have FDISK with multiple partition support.

Something like Ontrack Dynamic Disk Overlay, maybe? (I'm not sure if DDO is 286-compatible)

I've heared about Compaq DOS 3.31 which should support partitions > 32 MB.

Disruptor wrote on 2022-10-18, 18:47:

I've heared about Compaq DOS 3.31 which should support partitions > 32 MB.

I heard that, too..

Another idea was to change the ubiquitous 512 Bytes/per sector size to something bigger.
Some OEM versions of MS-DOS did this, I vaguely remember.
That was in the DOS 2-3 era, definitely before 1990.
Maybe intended for pure DOS compatible PCs, rather than IBM PC/XT compatibles.

Other OSes, like PC-MOS/386 had their own proprietary filesystem that did overcome the 32 MB limit.
With PC-MOS/386 v5 it was being deprecated, though.

Edit: I might have been possible that this "free" software was really lifting the 32MB limit a bit.
There's a patch for MS-DOS 5, which allows ~3GB partitions, for example.

Unfortunately, we may never know.
I mean, so many stuff was homebrewed in those days..
Many PC users in the 1980s learned how to modify and hack things, because a suiting commercial software didn't exist. Or wasn't known.
My father, for example, wrote his own floppy controller BIOS for his CP/M machine.
Such things weren't unheard of. So a little local PC store in say, Haifa/Seattle/London/[enter city/town] surely wasn't unlikely to have the know how to patch DOS a bit.
Most of these dudes there had worked with the stuff at home, too.
Maybe even written the software for their own purpose, originally.

Azarien wrote on 2022-10-18, 18:42:

Something like Ontrack Dynamic Disk Overlay, maybe? (I'm not sure if DDO is 286-compatible)

Very likely.
SpeedStor was a popular utility allowing >32 MB partitions with DOS <=3.30.

Hi again!

I found out about an vintage utility called "Advanced Disk Managment".

It had, - among other things -, the ability to create paritions beyond 32MB.
Up to 512MB, if I'm not mistaken. Very interesting.

Maybe this was one of the tools that were used in the DOS 2/3 times ?

Jo22 wrote on 2023-02-07, 23:10:

Hi again! […]
Show full quote

Hi again!

I found out about an vintage utility called "Advanced Disk Managment".

It had, - among other things -, the ability to create paritions beyond 32MB.
Up to 512MB, if I'm not mistaken. Very interesting.

Maybe this was one of the tools that were used in the DOS 2/3 times ?

hi,

Is there a documentation about how it work ?

Because without modifying DOS, it is impossible...
I would like to learn more how we can interface to / hack the DOS disk functions for my PicoMEM Project.

PM sent.

FreddyV wrote on 2023-02-08, 08:43:

Because without modifying DOS, it is impossible...

It's perfectly possible for unmodified DOS 3.30 to use partitions larger than 32 MB, but not boot off them.
With SpeedStor, DOS is booted off a regular partition (<= 32 MB), and SSTOR.SYS is loaded to access special partitions that can be larger.

Grzyb wrote on 2023-02-08, 11:10:

FreddyV wrote on 2023-02-08, 08:43:

Because without modifying DOS, it is impossible...

It's perfectly possible for unmodified DOS 3.30 to use partitions larger than 32 MB, but not boot off them.
With SpeedStor, DOS is booted off a regular partition (<= 32 MB), and SSTOR.SYS is loaded to access special partitions that can be larger.

Load a .SYS means modify DOS for me

FreddyV wrote on 2023-02-08, 12:38:

Grzyb wrote on 2023-02-08, 11:10:

FreddyV wrote on 2023-02-08, 08:43:

Because without modifying DOS, it is impossible...

It's perfectly possible for unmodified DOS 3.30 to use partitions larger than 32 MB, but not boot off them.
With SpeedStor, DOS is booted off a regular partition (<= 32 MB), and SSTOR.SYS is loaded to access special partitions that can be larger.

Load a .SYS means modify DOS for me

Does loading a mouse driver or Emm386 also mean DOS is modified to you ?

Because .sys is a driver nothing more.

TrashPanda wrote on 2023-02-08, 15:32:

Does loading a mouse driver or Emm386 also mean DOS is modified to you ?

Because .sys is a driver nothing more.

A .SYS is first an executable, that can modify the DOS functions themselves.

i was first thinking it could extend the partition size.
If it is only allow to have more partition, then, it is simple, but not standard anyway.

Hm. There's also PC-MOS/386, still. Older versions, at least, ran on 8086.
And can execute DOS applications, of course.

https://www.youtube.com/watch?v=LtHNEUEF2Iw

https://www.youtube.com/watch?v=7YkAVojQbi4

MOS also supported a proprietary partition type which broke the 32MB barrier.
Partitions could be up to 512MB in size, I vaguely remember.

PC-MOS/386 v5.01, the open-source release, can still use existing MOS partitions, I believe.
Merely the option to create them was removed, due to the invention of FAT16B.

There's an old article/test about PC-MOS/386.
It's wonderfully pessimistic, also, quite fitting to our modern Zeitgeist. ;)