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2019
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Restoration Card - Working Principle
The principle of the hard disk protection card is that it takes over the INT13 interrupt for reading and writing operations on the hard disk. When the system starts, the protection card first takes control of the INT13 interrupt address with its own program. This way, any read or write operation on the hard disk must go through the protective program of the protection card for secure reading and writing. This means that the FAT file allocation table, the hard disk master boot record, CMOS information, interrupt vector table, and other information are first saved into the temporary storage unit within the protection card.
The principle of the hard disk protection card is simple: it takes over the INT13 interrupt for reading and writing operations on the hard disk. When the system starts, the protection card first takes over the INT13 interrupt address with its own program. Thus, for any read or write operation on the hard disk, it first saves information such as the FAT file allocation table, the hard disk master boot record, CMOS information, and the interrupt vector table into the temporary storage unit within the protection card. Whenever we write data to the hard disk, it actually completes the write operation to the hard disk, but does not truly modify the FAT on the hard disk. It may even write to a backup FAT table, which is why all write operations appear to be nonexistent after a system reboot.
The main body of the restore card is a hardware chip that works in conjunction with the hard disk's MBR (Master Boot Record) on the motherboard. Most restore cards operate on similar principles, and their driver loading method is very similar to boot viruses under DOS: they take over the BIOS's INT13 interrupt, saving the FAT, boot sector, CMOS information, and interrupt vector table into the card's temporary storage unit or in a hidden area on the hard disk, using their own interrupt vector table to replace the original one; additionally, they save the FAT information into the temporary storage unit to handle modifications to the internal data of the hard disk; finally, they find a portion of continuous empty disk space on the hard disk and save our modified data there.
The hard disk protection card plays a very important role in the management of computer rooms in schools, basically achieving the goal of "one card worry-free." After using the hard disk protection card, maintenance of the computer room is greatly reduced, and there is basically no need to worry about viruses, misoperations, and other issues. Of course, if the hard disk suffers physical damage, the hard disk protection card is powerless. It can restore the computer hard disk to its original state in most cases of non-physical damage. In other words, whether it is a virus, accidental modification, accidental deletion, or destruction of the hard disk's content, it can be easily restored.
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