Disruptor wrote on 2025-01-05, 09:32:

Don't create partitions for DOS usage using Windows Vista, 7, 8, 8.1, 10 or 11.
DOS needs classic CHS aligned partition scheme.
Above listed operating systems do not care about compatiblity with CHS.

The partitions were created using FreeDOS. I just copy data to those partitions in Windows 11.

zuldan wrote on 2025-01-05, 07:26:

FDISK on FreeDOS worked perfectly. I now have C: 2GB and D: 1.7GB primary partitions on DOS 6.22 AND Windows 11. Woohoo.

Now that's a surprise!
I always thought that MS-DOS doesn't support more than one primary partition per drive...
but it seems that it can't *CREATE* more than one primary - but if you create them with third-party software, MS-DOS can use them.

How did you format both partitions?
With FreeDOS, or MS-DOS ?

Can MS-DOS tools like CHKDSK or SCANDISK work on both primaries?

Grzyb wrote on 2025-01-05, 10:06:

Now that's a surprise! I always thought that MS-DOS doesn't support more than one primary partition per drive... but it seems th […]
Show full quote

zuldan wrote on 2025-01-05, 07:26:

FDISK on FreeDOS worked perfectly. I now have C: 2GB and D: 1.7GB primary partitions on DOS 6.22 AND Windows 11. Woohoo.

Now that's a surprise!
I always thought that MS-DOS doesn't support more than one primary partition per drive...
but it seems that it can't *CREATE* more than one primary - but if you create them with third-party software, MS-DOS can use them.

How did you format both partitions?
With FreeDOS, or MS-DOS ?

Can MS-DOS tools like CHKDSK or SCANDISK work on both primaries?

It appears it’s just a limitation of FDISK in DOS v6.22. I formatted the partitions in FreeDOS but I suspect formatting them in DOS v6.22 would work as well. I haven’t tried CHKDSK or SCANDISK yet.

My 4GB CF card setup is also 2GB+2GB done via DOS 6.22 FDisk with Primary+Extended/Logical. Win11 fully recognizes it and I can see both drives in file explorer. The only annoying thing is how Win11 places its trash "System Volume Information" on each drive as soon as I connect the CF card to the Windows machine. I typcially delete it on the DOS machine using Norton Commander.

wbahnassi wrote on 2025-01-05, 14:41:

My 4GB CF card setup is also 2GB+2GB done via DOS 6.22 FDisk with Primary+Extended/Logical.

Yes, that's the official DOS way.

Win11 fully recognizes it and I can see both drives in file explorer.

But that's confusing - looks like Windows 11 isn't consistent here.

The only annoying thing is how Win11 places its trash "System Volume Information" on each drive as soon as I connect the CF card to the Windows machine. I typcially delete it on the DOS machine using Norton Commander.

Yes, the neverending annoyance of Windows - 9x trashes the boot sector with "IHC", modern versions trash the root directory with "System Volume Information".
In both cases it's possible to disable that nasty behavior, but the best idea is to always write-protect any important media...

hi i need 2 primary dos partition for dual boot PC DOS 6.3 and OS/2 1.30
no extended and logical
os/2 insist to install on primary not logical
also pc dos insist to install on primary
also os/2 need seprated partition from dos
how can i make 2 primary dos partition on my hard drive ?
i can not use cd to boot. my computer have no ide port to install cdrom
also i can not connect my hard disk to other computer bacaus ist not ide or sata it has MSA Conector only.

iirc you can create up to 4 primary partitions

Correct. DOS Fdisk will not let you create more than one primary DOS partition, but you may have up to 4 per disk.

DOS fdisk will only let you have a single partition marked as active, even though it's on another drive. If it reads one active anywhere, it will balk setting it other than off. (Iirc)

DOS emumerates drives this way (IIRC, i'm getting old) on boot:

Boot HDD is enumerated first. (If partition 2 is set active, and is booted, and partition 1 is a primary dos partition, partition 2 will be C, partition 1 will be D)

if booted from floppy, the first dos partition on the first disk is enumerated first. (Iirc)

primary dos partitions on the first disk are enumerated next, in order, if present.

Logical drives on the first disk are then enumerated, in order.

If more than one extended dos partition exists, numeric order of the partitions determines the order that the groups of logical drives are enumerated.

This repeats for each additional disk, in order.

Grzyb wrote on 2025-01-05, 10:06:

Now that's a surprise! I always thought that MS-DOS doesn't support more than one primary partition per drive... but it seems th […]
Show full quote

Now that's a surprise!
I always thought that MS-DOS doesn't support more than one primary partition per drive...
but it seems that it can't *CREATE* more than one primary - but if you create them with third-party software, MS-DOS can use them.

How did you format both partitions?
With FreeDOS, or MS-DOS ?

Sorry for the necro. But that's incorrect.
MS-DOS up to 6.22 only can mount one primary partition at a time.

The DOS of Windows 9x can mount two primary partitions, but they must be of different type. One LBA, one non-LBA.
I use that trick in multi configs, like Win9x + DOS + Win2000. 4th partition is an non-LBA extended with a 2 GB FAT16 partition for data exchange.
Active partition can be changed with FDISK but I prefer to integrate Win9x' and DOS' partition bootsector into Win2000 bootmanager having a boot menu then.
Of course, the OS/2 Warp bootmanager works fine too.

However, it's a bit tricky to create those partitions.
I trick they system by hiding partitions (changing partition type from 0x to 1x with a disk editor, like NU.EXE from The Norton Utilities 4.5, Advanced Edition).