MBR is damaged
What will happen if the first sector has been damaged (by virus, for example)?
The first 16 bytes are overwritten with zeros.
- 000000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
- 000000010 BF 1B 06 50 57 B9 E5 01 F3 A4 CB BE BE 07 B1 04 ?..PW?a.o¤E??.±.
When trying to boot after hardware testing procedures, a blank screen appears without any messages. It means that the piece of code at the beginning of the MBR could not be executed properly. That´s why no error messages could even be displayed. However, if booting from a floppy, the FAT partition can be seen as-well-as files and are able to perform standard operations like file copy or program execution...
It´s possible because, in the example, only part of the MBR has been damaged which does not allow the system to boot properly. In this case, the partition table is safe and drives can be accessed when booting from the operating system installed on the other drive.
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What will happen if the sector signature (last word 0x55AA) has been removed or damaged?