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Liam Wilson Member
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What Is the Master Boot Code?
Definition of Master Boot Code & Help Fixing Master Boot Code Errors
By Tim Fisher Tim Fisher Senior Vice President & Group General Manager, Tech & Sustainability Emporia State University Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the VP and General Manager of Lifewire.
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Zoe Mueller 4 minutes ago
lifewire's editorial guidelines Updated on January 26, 2022 Tweet Share Email Tweet Share Email Wind...
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Liam Wilson 5 minutes ago
Specifically, in the typical generic master boot record, the master boot code consumes 446 bytes of ...
lifewire's editorial guidelines Updated on January 26, 2022 Tweet Share Email Tweet Share Email Windows The Ultimate Laptop Buying Guide The master boot code (sometimes abbreviated as MBC) is one of the several parts of the master boot record. It performs the first set of important functions in the process of booting.
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Kevin Wang 3 minutes ago
Specifically, in the typical generic master boot record, the master boot code consumes 446 bytes of ...
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Lily Watson 2 minutes ago
A master boot code is used only on primary partitions. Non-active partitions like those on an extern...
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Andrew Wilson Member
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Specifically, in the typical generic master boot record, the master boot code consumes 446 bytes of the total 512-byte master boot record—the remaining space is used by the partition table (64 bytes) and the 2-byte disk signature. Anthony Bradshaw / Photographer's Choice / Getty Images
How the Master Boot Code Works
Assuming the master boot code is executed properly by BIOS, the master boot code hands off booting control to the volume boot code, part of the volume boot sector, on the partition on the hard drive that contains the operating system.
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Ryan Garcia Member
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A master boot code is used only on primary partitions. Non-active partitions like those on an external drive that may store data like file backups, for example, don't need to be booted from because they don't contain an operating system and therefore have no reason for a master boot code. These are the actions the master boot code follows, according to Microsoft: Scans the partition table for the active partition.
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Isaac Schmidt Member
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Finds the starting sector of the active partition. Loads a copy of the boot sector from the active partition into memory.
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Mia Anderson 10 minutes ago
Transfers control to the executable code in the boot sector. The master boot code uses what's ca...
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Kevin Wang Member
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Transfers control to the executable code in the boot sector. The master boot code uses what's called CHS fields (Starting and Ending Cylinder, Head, and Sector fields) from the partition table to locate the boot sector portion of the partition.
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Master Boot Code Errors
Files that Windows needs to boot to the operating system can some...
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Joseph Kim 6 minutes ago
While this may be your first thought because you don't want to go through the process of fixing the ...
Files that Windows needs to boot to the operating system can sometimes become corrupt or go missing. Master boot code errors can happen due to anything from a virus attack that replaces the data with malicious codes, to physical damage to the hard drive.
Identifying Master Boot Code Errors
One of these errors are likely displayed if the master boot code can't find the boot sector, preventing Windows from starting: Missing operating systemInvalid partition tableError loading operating systemMBR Error 1MBR Error 2 One way you can fix errors in the master boot record is to reinstall Windows.
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Elijah Patel 2 minutes ago
While this may be your first thought because you don't want to go through the process of fixing the ...
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Zoe Mueller Member
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While this may be your first thought because you don't want to go through the process of fixing the error, it's a rather drastic solution. Let's look at a few other, potentially more simple, ways to fix these problems:
How to Fix Master Boot Code Errors
While you can normally open a Command Prompt to run commands in Windows, problems with the master boot code likely mean that Windows won't start. In these cases, you'll need to access a Command Prompt from outside of Windows...
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Joseph Kim 1 minutes ago
In Windows 11, Windows 10, Windows 8, Windows 7, and Windows Vista, you can attempt to fix a master ...
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Madison Singh 5 minutes ago
In Windows 7 and Windows Vista, you can run the same command, but it's done via System Recovery Opti...
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Madison Singh Member
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In Windows 11, Windows 10, Windows 8, Windows 7, and Windows Vista, you can attempt to fix a master boot code error by rebuilding the Boot Configuration Data (BCD) using the bootrec command. The bootrec command can be run in Windows 11/10/8 through Advanced Startup Options.
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Emma Wilson 7 minutes ago
In Windows 7 and Windows Vista, you can run the same command, but it's done via System Recovery Opti...
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Elijah Patel Member
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In Windows 7 and Windows Vista, you can run the same command, but it's done via System Recovery Options. In Windows XP and Windows 2000, the fixmbr command is used for building a new master boot record by re-writing the master boot code.
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Noah Davis Member
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This command is available in Recovery Console. Was this page helpful?
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What Is the Master Boot Code? (MBC Definition) GA
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