China DOS Union

Today, I carried out a formal test of the so-called hard disk "logical lock". The results are as follows:

The boot disks used in the test were:
MS-DOS 7.10 (Win98) boot floppy
MS-DOS 6.22 boot floppy
PC-DOS 7.10 boot floppy
ROM-DOS 7.10 boot floppy
Windows 2000 boot CD

As a result, the operating systems that could not boot were:

MS-DOS 7.10 (Win98) boot floppy
MS-DOS 6.22 boot floppy (hangs at "Starting MS-DOS"

The operating systems that could boot normally were:

PC-DOS 7.10 boot floppy (everything boots normally, but of course the hard disk cannot be recognized)
ROM-DOS 7.10 boot floppy (everything boots normally, but of course the hard disk cannot be recognized)
Windows 2000 boot CD

This shows that only Microsoft's MS-DOS 4.0-8.0 cannot boot.

Tomorrow I will continue testing more boot disks, such as FreeDOS, RxDOS boot disks, and so on.

Just now I also tested the boot disks of FreeDOS(beta8) and RxDOS(6.2) after the hard disk had been hit with the "logical lock". The results are as follows:

FreeDOS boot floppy: on startup it reports that the hard disk has an error, and it can boot completely normally.
RxDOS boot floppy: when starting up, the hard disk light keeps flashing, and like MS-DOS it falls into an infinite loop and cannot boot.

Therefore, among MS-DOS, PC-DOS, ROM-DOS, FreeDOS, and RxDOS, only MS-DOS and RxDOS will be locked by the "logical lock".

I actually forgot to test DR-DOS yesterday. Today I made a DR-DOS 7.03 boot floppy, and after locking the hard disk with the "logical lock", the result was that DR-DOS, like MS-DOS, also could not boot. With that, the result is very clear:

DOSes that will not be locked by the "logical lock":

PC-DOS
ROM-DOS
FreeDOS

DOSes that will be locked by the "logical lock":

MS-DOS 4.0-8.0
DR-DOS 7.03
RxDOS 6.2

Just now I also tested the PTS-DOS Pro 2000 boot disk, and as expected, it could boot completely normally.

After that I also tested DR-DOS 7.05, and found that the DR-DOS 7.05 boot disk booted completely normally with the hard disk locked, while DR-DOS 7.03 would not. It seems version 7.05 really is better than version 7.03.

With that, it has been confirmed that the following (higher-version) DOSes are not affected by the "logical lock":

PC-DOS 7.10
ROM-DOS 7.10
DR-DOS 7.05
FreeDOS beta8(7.10)
PTS-DOS Pro 2000(6.90)

With these test results, it'll be easy to handle now~~~ Thanks for the hard work, moderator~~

Someone mentioned a method of modifying MS-DOS's IO.SYS file. That is a very poor method. Not only is it troublesome, but whether the hard disk is good or not, the modified IO.SYS on the boot disk cannot recognize the hard disk. So this so-called modification simply makes IO.SYS completely fail to recognize the hard disk under any circumstances. But the boot disks of PC-DOS, DR-DOS, ROM-DOS, FreeDOS, and PTS-DOS Pro 2000 mentioned above can all boot completely normally even when the hard disk has been locked. Of course the hard disk cannot be recognized at that time, but if the hard disk is good, then naturally they can recognize and use the hard disk normally.

What is a logical lock?

Very good, the DOS forum needs exactly this kind of spirit of exploration!!!!

Classic nostalgia:

A "logical lock" is a tool bundled with software like KV300 that is used to lock MS-DOS.

Moderator: PC-DOS 7.10 boot floppy (everything boots normally, but of course the hard disk cannot be recognized)

In this situation, can DM recognize the hard disk and zero it out?

I found that the so-called universal-version DM nowadays is actually Seagate's DM! If I set a Quantum hard disk to NONE in COMS, then DM can't detect it; if it's a Seagate, this method works! (I've used this method to repair Seagate hard disks!)

Moderator: what method do you use to restore normal hard disk use without clearing the data on the hard disk?!

Please give me a few pointers! Thanks!

I just carried out some further tests on a hard disk that had been locked. After booting with a ROM-DOS 7.10 boot floppy while the hard disk was locked, I observed what happened after running FDISK (the one in MS-DOS 7.10), NDD 2002, and DiskEdit 2002. As a result, I found that under these circumstances all three of these programs could recognize the hard disk, let alone DM (xn168xue: when I said that after PC-DOS boots it cannot recognize a locked hard disk, I only meant that drive C is invalid, but disk tools can all recognize it). By contrast, after booting from a floppy by using the method of modifying MS-DOS's IO.SYS, none of these three programs can recognize the hard disk. It can be seen that the hard disk "logical lock" really has no effect at all on PC-DOS 7.10 and ROM-DOS 7.10 boot disks. Below are the specific results of my use of FDISK, NDD 2002, and DiskEdit 2002:

FDISK: Since the principle of the "logical lock" is a circular partition linked list, FDISK displays four completely identical partitions, of which the first is an extended partition and the other three are non-DOS partitions. It is also possible to perform operations such as deleting and creating these partitions.

DiskEdit 2002: Through the "physical disk" item, it can open the hard disk completely normally and perform operations such as modifying disk contents.

NDD 2002: It can recognize the hard disk, but it prompts, "The hard disk has errors. Repair it?". Since this is my own hard disk, I didn't dare let it repair it. If I had an old hard disk, then I could continue testing.

Mr. Mo: You have an old unused hard disk, so after locking it, why not boot with the ROM-DOS 7.10 boot disk and run NDD 2002 to see its repair results.

Moderator, you also said: what method do you use to restore normal hard disk use without clearing the data on the hard disk?!

Also: I downloaded the PCDOS and ROMDOS you provided, and they are both 1.40M, but the actual capacity of my ordinary floppies is only 1.38M, so they won't fit!

HD-COPY automatically generates a 1.44M floppy disk image. Even if the disk is not full, it will still automatically adjust it to 1.44M. You can take out a blank disk; if it isn't blank, just use FORMAT or other commands to reformat it as 1.44M.

As for whether NDD can completely repair a locked hard disk, since I have no way to test it, that still requires further verification from Mr. Mo.