Do you have any idea about Master Boot Record (MBR)?
This concept was firstly publicly introduced in 1983 with PCDOS2.0.
The MBR holds the information on how thelogical partitions, containingfile systems, are organized on thatstorage medium.
It also contains executable code to function as a loader for the installed operating system.
The maximum addressable storage space of MBRpartition tableis 2TB (2^32512 bytes).
Therefore, the MBR-based partitioning scheme is gradually being replaced by the GUID Partition Table (GPT) scheme.
MBR cannot exist on non-partitioned media like floppies.
Overview
In general, there are two kinds of definition for MBR.
Broadly speaking, MBR contains the entire sector (bootstrap, partition table and separation identifier).
While in a narrow sense, it only refers to bootstrap.
And the loader code is variable.
Thus, users can boot MBR from multiple operating systems.
It can be found in FDISK program.
2:Disk PartitionTable (DPT)
The partition table describes the partitions of a storage equipment.
The total partition table is 64 bytes long, and each partition entry is 16 bytes long.
Therefore, there is a maximum of 4 partitions on MBR disk.
3: END Signature
Its value is AA55.
But it may look like 55AA since the low value will be in front of the high.
After that, the system bootstrapping will read the MBR from CHS to memory.
And then, it can execute the master boot record.
Besides, it can help to store the contents of the first logical sector of theactive partitioninto memory.
And, the contents of the sector is called dos boot record (DBR).
Next, BIOS reads the first sector namely MBR sector to 0000: 7C00H.
Then, BIOS reads 0000: 7CFEH-0000 to see whether the end signature is 55AAH.
If it is, BIOS will pass control to MBR to load Windows.
If not, BIOS will read other bootable devices.
Rebuild MBR
In some case, mistaken operation or computer virus invasion may damage MBR.
As a result, when launching computer, users just see a black screen or see some nonsense letters.
Aiming at this situation, they can turn to some solutions, like:
DOS commands: fdisk /mbr
