Hard Disk "logical lock" SOLUTION

Many computer users have seen or heard that when the so-called "logical lock" is applied to a hard disk, no matter whether it is a floppy disk, hard disk, or a CD, some computers cannot be started. So what is "logical lock?
The so-called "Hard Disk logical lock" is made by using some dos errors. It uses the "cyclic Partition Table" technology, so that some dos with this error cannot be started with any device, including a floppy disk and other mobile devices. When DOS is started, the system automatically searches for information about each partition on the hard disk, such as the type and size, to enable the system to identify the hard disk, they are allocated to C, D, E, F, and other drives, allowing users to perform various operations on them. Logical locks take advantage of this point. By modifying the Partition Table of the hard disk, the partition table loops, that is, the first logical disk of the extended partition points to itself, this causes certain DOS systems to fail to start when they find partitions in a life cycle.
It can be seen that this is actually caused by an error during DOS Startup. It is said that as early as 1992, an anti-virus expert called Mike found the problem and reported it to the DOS manufacturer with the problem, such as the production of PC-DOS IBM Company, the production of DR-dos/novelldos Novell Company, the production of MS-DOS Microsoft Company and so on. Soon after, IBM, Novell and other companies have announced that their new DOS version has completely solved this problem, only have MS-DOS of Microsoft companies ignored, resulting in a new version of the MS-DOS, such as 6.x, 7. X and so on.
However, because Microsoft's MS-DOS is the most widely used, so its impact and harm is also the biggest. Once the user's hard disk is "logical lock" lock, a variety of Microsoft operating systems, such as MS-DOS 5.x/ 6.x/ 7.x/ 8.0 boot disk can not be started, resulting in a hardware fault photo, and many experts are helpless. This kind of image is terrible and will make computers unusable. So many people are looking for preventive measures and solutions. In fact, it is not difficult to solve the problem. The following describes several solutions.

* Start with a non-MS-DOS Operating System

From the above, we can see that the "Hard Disk logical lock" mainly affects Microsoft's MS-DOS system, so you can use other DOS to start. For this reason, I have specifically designed several more practical versions of DOS, such as MS-DOS 7.10, PC-DOS 7.10, Dr-dos 7.05, ROM-DOS 7.10, freedos beta9, PTS-DOS Pro 2000 boot disk in the hard disk "logical lock" in the case of a start test, the result is as follows:

PC-DOS 7.10 Boot Disk: boot all normal;
Dr-dos 7.05 (Version: 7.10) Boot Disk: Boot is normal;
ROM-DOS 7.10 Boot Disk: boot all normal;
Freedos beta9 (Version: 7.10): When the disk is started, an error is displayed, and the disk is fully started;
PTS-DOS Pro 2000 (Version: 6.90): boot everything works.

Note: The above various dos are very stable, and support FAT32 partition and big hard disk, of which ROM-DOS 7.10 also fully local support for long file names, and the compatibility is very good.

Therefore, you can use more than one dos boot disk to start a hard disk with a "logical lock". The drive letter (such as C :) of the hard disk that has been locked after startup, although not visible, however, various disk partitioning software, such as Norton disk editor 2002, Norton disk doctor 2002, and fdiskProgramCan display the locked hard disk. In this case, you can use the diskedit or other tools mentioned above to view or manually repair the hard disk, or use some software to automatically repair the hard disk, such as netresq and srctools, to completely remove the "logical lock" on the hard disk, and the data on the hard disk will not be damaged.

* Start with a fixed MS-DOS boot disk

although the MS-DOS boot disk in the normal state can not be locked in the hard disk to start the computer, but because it is only the MS-DOS boot file IO. A bug in SYS, so as long as the bug is fixed, the MS-DOS boot disk will not be affected by the "logical lock" and can be started normally. However, you should use the correct method to fix bugs. Some people have mentioned how to solve the problem by modifying the hard disk partition mark "55aa" in Io. SYS. In fact, this method is very bad. Because, this method is actually to make Io. sys completely ignores the existence of the hard disk, that is, by skipping the hard disk to start the floppy disk. In this way, the hard disk cannot be identified no matter whether the hard disk is locked or not, therefore, this boot disk cannot be used as a normal MS-DOS boot disk. On the contrary, if you use the correct method to fix Io. in sys, if the hard disk is good after being started with this floppy disk, it can be identified normally, even if the hard disk is locked by a "logical lock, it can also be like the above method (that is, "starting an operating system with a non-MS-DOS ") as mentioned in the PC-dos, Dr-dos, Rom-dos, freedos, PTS-DOS pro and so on boot floppy disk after further repair operations. Some earlier versions of the MS-DOS, such as the boot disk of version 3.2, were also mentioned to start the computer. However, this obviously has many disadvantages: first, it is difficult to find the DOS of the old version, second, because its version is too low, its functions are very small, and its compatibility is also poor; third, these earlier versions of DOS do not support large hard disks (not even 32 m), logical partitions, and so on, and even cause real damage to the hard disk, MS-DOS 3.2 and other versions even do not know 1.44m floppy disk. It can be seen that the method of starting with a lower version of The MS-DOS is not very feasible. Therefore, it is important to use a good method to correct bugs in Io. sys of a later version of The MS-DOS. With MS-DOS 6. for example, you only need to use any hexadecimal Editor (such as pctools) to find Io. in the Sys File, replace the hexadecimal string "07 72 03" with "06. Some other versions of the MS-DOS can also use similar methods, such as MS-DOS 7.10 Io. sys specific modification method see "computer expert network forum ". In this way, Microsoft's MS-DOS boot disk can also be like a variety of other dos in the hard disk is locked by the logic lock under the normal start.

All of the methods mentioned above are the most direct solution to the "logical hard disk lock" (that is, "Use a DOS boot disk not affected by the 'logical lock' to start the computer"), which is also the best solution. Therefore, as long as you make a boot disk of any of the above mentioned (such as PC-DOS 7.10 boot disk, ROM-DOS 7.10 boot disk, freedos boot disk, or repair MS-DOS boot disk, etc.) can be. It can be used as a normal boot disk at ordinary times, and can be used to start and solve problems when the hard disk is locked.
Some people also mentioned other "methods", such as hot swapping of hard disks and low DMUs, which are not only troublesome and dangerous, but also may cause damage to all data in the hard disk. For example, after hot swapping of the hard disk (you need to unpack the machine and take down the hard disk, and re-mount the hard disk after it is started, it is very troublesome and dangerous), even if it is started successfully with a floppy disk, at this time, the hard disk will be completely unrecognizable, including a variety of Hard Disk tools. If you skip BIOS with DM, all data on the hard disk will be lost and cannot be recovered. It can be seen that hard disk hot swapping and other "methods" are neither practical nor feasible.

Therefore, as long as you find a good solution and perform corresponding operations, the so-called "Hard Disk logical lock" can be easily solved. You may try it.