China DOS Union

I recently connected a second hard disk to my machine for some testing, and after booting into DOS the system does not assign drive letters to the logical partitions on the second hard disk.
Both of my hard disks use very standard partition layouts (each has one primary partition, plus one extended partition containing several logical partitions).
After booting into DOS, the drive letters assigned by the system are like this:
First hard disk primary partition (FAT32) is C：
Second hard disk primary partition (FAT32) is D：
Under the first hard disk’s extended partition there are two FAT32 logical partitions, E： F：
There is nothing wrong with any of that, but under the second hard disk’s extended partition there are also three FAT32 logical partitions, and the system simply does not assign them any drive letters at all. After that it goes on to assign G： to the CD-ROM. Why is this?

I tested booting into DOS in these three ways:
Win 98 startup floppy,
unmodified Wengier, 2004-2-14 Super MS-DOS 7.10 Boot Disk
when booting WIN98, press F8 and choose item 5 “Command prompt only”
In all three cases, the situation is the same.

But when I boot into Windows 98, 98 normally assigns G： H： I： to the logical partitions on the second hard disk, and only then assigns J： to the CD-ROM.

I have tested connecting the second hard disk as slave on IDE1, and as master or slave on IDE2, and the result is the same.
I also replaced the second hard disk with another drive of a different model, and the result is still the same.

Could the experts please advise what possible causes might produce this phenomenon?

Bump...

I still haven’t found an answer to my question.
Hoping an expert can point me in the right direction

Your situation is very strange, I’ve never run into it before.
In DOS, enter FDISK and choose option 5 to check how the drive letters are assigned for the partitions on the two hard disks.

Many thanks for your attention!
I also think this phenomenon is quite strange.

In both FDISK and PQMAGIC, the drive letters that should be assigned are displayed correctly.
But after DOS boots, they just do not get assigned, while everything is normal after booting into Windows.

I used Ghost partition copy to copy the first partition of the first hard disk to the first partition of the second hard disk (with Win 98 installed on it).
Then I entered BIOS settings and changed the first boot device from HDD 0 to HDD 1 (that is, set it to boot from the second hard disk). At that point, if I press F8 during startup and enter command-line mode, I find that the system can assign drive letters correctly.

My preliminary suspicion is that the partition structure on my first hard disk has some bizarre fault...
Still messing around with it

Because I hadn’t made any progress for a long time, I had originally already given up on this question. Today, an accidental discovery turned things around, so I’m coming back to this thread to report to all the friends who were concerned about this issue:

The two hard disks connected on my machine are: main hard disk ST380021A (Seagate 80G), secondary hard disk: Quantum 4G

Main hard disk: primary partition 5G, all remaining space made into an extended partition (containing several logical partitions, of which 2 are FAT32)
Secondary hard disk: primary partition 1G, all remaining space made into an extended partition (containing two logical partitions, both FAT32)

FDISK cannot correctly recognize the capacity of the ST380021A. I tested partitioning with GDISK and SPFDISK respectively. After partitioning the main hard disk, the system ID of the extended partition was automatically set to 0F.
But whether I used FDISK, GDISK, or SPFDISK, the system ID of the extended partition on the secondary hard disk (the Quantum 4G one) was always automatically set to 05.

And that is where the problem came from. Testing gave the following results:

The default state is: the main hard disk’s (Seagate 80G) extended partition system ID is 0F, and the secondary hard disk’s (Quantum 4G) extended partition system ID is 05. In this case, the DOS system does not assign drive letters to the logical partitions under the secondary hard disk’s extended partition (which is exactly why I started this thread).

If I manually change the main hard disk’s (Seagate 80G) extended partition system ID to 05, then after reboot the DOS system no longer assigns drive letters to the FAT32 logical partitions inside the main hard disk’s (Seagate 80G) extended partition, but it does assign drive letters to the logical partitions on the secondary hard disk (Quantum 4G).

If the main hard disk’s (Seagate 80G) extended partition system ID is kept at the default 0F, while I manually change the secondary hard disk’s (Quantum 4G) extended partition system ID to 0F, then after reboot the DOS system correctly assigns all drive letters.

At this point the problem is solved!



Additional note: from the explanation of system IDs in SPFDISK, I saw that 05 means “extended partition” while 0F means “large extended partition”.
Because my DOS knowledge is limited, I do not know from what capacity onward it counts as a “large extended partition”, and because of limited time and conditions I have not done further testing for the moment.
If there is only one hard disk (for example, when I tested either one of the two hard disks by itself), then with the several partitioning tools I used, the default system ID settings do not produce this no-drive-letter phenomenon. For example, if the Quantum 4G is connected by itself, it is perfectly normal for its extended partition to remain at the default 05. But when it is used as the slave drive, and the preceding master drive’s extended partition system ID is 0F, then no drive letters get assigned.

This phenomenon does not occur after booting into Windows. In other words, even if no drive letters are assigned under DOS, after booting into Windows 98/2000/XP all the drive letters that should be assigned are handled completely correctly.

Both SPFDISK and DISKMAN provide the function of manually modifying partition system IDs, but unfortunately neither of these two tools can manually modify the system ID of an extended partition (or perhaps I didn’t find the method?). I had no choice but to use DISKEDIT to manually modify the relevant data in the MBR to achieve the result...

Thanks to all the friends who paid attention to this issue!

The maximum size supported by FAT32 for a single partition is 32GB. Disk 1: 32x2+5=69<80
So DOS can’t recognize the logical drives on disk 1.
It should be that the logical drive letters on disk 1 were not assigned.