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Questions tagged [mbr]

Master Boot Record: the first sector on disk, containing partition info

A Master Boot Record (MBR) is a special type of boot sector at the very beginning of partitioned computer mass storage devices. The MBR holds the information on how the logical partitions, containing file systems, are organized on that medium.

It identifies how and where an operating system is located, so that it can be bootstrapped.

Wikipedia with full partition table info

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Master Boot Record maximum drive size

I am reading up a bit on Master Boot Record layout and I was particularly interested in how the partition layout causes a size limitation on the size of the storage that can be used on a device with MBR. Each partition within an MBR is defined using…
sshekhar
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Toggle readonly filesystem for changes

I have a readonly filesystem on my bootable usb drive. I want to modify some text files in there and then bring it back to readonly after modify it. I tried : sudo hdparm -r0 /dev/sdb I also tried : mount -o remount,rw /dev/sdb mount: /dev/sdb:…
yGangina
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How is MBR stored if the sector size is bigger than 512 bytes?

So as far as i know, MBR size is 512 bytes and it ends with 0x55AA. My questions are : How common is it for disks to have a sector size bigger than 512 bytes ? (eg disks used in servers, etc) How will MBR get stored if sector size is for example…
Notoriouss
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How does the MBR change between operating systems?

How does the Master Boot Record (MBR) change? I can not figure out if there is an MBR specific to Linux-based operating systems, or does each operating system have a different MBR? How do I compare MBRs of operating systems? And if I write one with…
user14189198
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MBR Structure, no partition detected

I'm currently trying to decode the MBR of my memory card for learning purpose. I've read many documents that are saying that partition tables are always start at 0x1BE of the MBR (first 512 bytes). All fields of the structure are okay except the…
Arnaud F.
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How to Solve 'bootloader.asm:30: error: TIMES value -44 is negative' Problem in NASM

I'm developing a Hello World kernel and bootloader...I wrote this code but when I try to compile it via NASM It says : "bootloader.asm:30: error: TIMES value -44 is negative". bootloader.asm: [BITS 16] [ORG 0x7C00] MOV DL, 0x80 MOV DH, 0x0 MOV…
Arda AKKAYA
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byte order when reading hard drive MBR

I printed the MBR of my Pentium M laptop's hard drive. Here is the command I used: $ sudo od -N 512 -x /dev/sda I would expect to get bytes in sequential order in the output, but it seems that every pair of bytes is reversed. For example, the…
prm.cs1
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Difference/Similarity between VBR and EBR

What is the difference between Volume Boot Record and Extended Boot Record? Are they same or different? Do they occupy first 512 bytes of partition/volume? I have read wiki articles but can't seem to find out if they are one and the same.
balajir712
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Master boot record shows no active partitions?

I used the following command to check the MBR code in hexadecimal hd -n 512 -v /dev/sda Which displayed this: It seems to me, that there is only one partition there. I have dual boot with linux and windows, shouldn't at least there be two? And,…
Tiago Oliveira
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Assembly Commands Are Running without Me Explicitly Calling Them

So I was trying to learn some assembly code when I came across this tutorial with source code. Now Ive compiled it and ran it with a working output: Booting from hard disk... Hello, World Goodbye 0x12fe But the problem is when I review the code,…
Aidan Bradley
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MBR and magic number understanding Question

First of all thanks for showing interests in helping me, so I try to understand how the bootloader works and i searched a little bit and found the following. The MBR has a size of 512 bytes, minus the 4 partition tables which are 64 bytes, we have a…
S Nell
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How to read MBR data on windows system

I'm using a file that has MBR code at an offset of 54 bytes. In the main() function, I'm calling OpenMBbrFile(), then ReadMbrData(). However, I'm not able to read MBR in my Buffer Properly. Please Help Me with the…
user9059547
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Python Parsing MBR

I am just starting out with Python scripting and I am trying to write a program that will parse through a provided MBR but I'm not sure how to start. I want to write a program that will parse a portion of the MBR's partition table. The first…
Segismundo101
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How Do I Backup the Windows Master Boot Record with C#?

Using C#, how do I backup the Windows Master Boot Record of the system booted hard drive? It's for an Antivirus engine.
Volomike
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writing bootloader in first sector of USB Pen drive in windows

I have written a simple bootloader for x86 using NASM and it was converted into boot.bin,i wrote first logical sector of USB Pendrive using dd(in Windows, downloaded from chrysocome site) but it is not taken when i try to boot with actual PC(used…
Prabakaran
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