What is Master Boot Record (MBR) ?

foreign [Music] have you ever wondered how your computer knows where the operating system is located on the hard drive and how it loads after booting when you turn on your computer it goes through a series of processes before it loads your operating system one of the most important of these steps is the master boot record or MBR in this video we'll explore the MBR how it works and why it's so important the hard drive contains a spinning platter with a delicate magnetic coating a head moves over the platter reading or writing zeros in ones as Tiny areas of magnetic north or south on the platter in a hard disk data is stored in tiny concentric tracks on the disk's surface which are arranged from the inner to the outer edge of the platter each circular path on the surface of a disk is called a track on which information is magnetically recorded a circular sector also known as a geometric sector or disk sector is the portion of the disk each track is divided into sectors as shown here a disk sector is the minimum storage unit of a hard drive with has a size of 512 bytes in computer file systems a cluster is a unit of disk or cluster of sectors allocated for files and directories the first sector of the hard disk hosts the MBR it is a small piece of code that's located at the very beginning of your hard drive it's only 512 bytes in size exactly one sector of space the MBR is divided into three main parts bootloader code the first 446 bytes of the MBR are reserved for the bootloader code which is responsible for loading the operating system into memory and starting its execution partition table the next 64 bytes of the MBR are reserved for the partition table which describes the location of the individual partitions the partition table is divided into 416 by entries each describing a single partition food signature the last two bytes of the MBR are reserved for the booth signature which is a two byte value that indicates that the MBR is valid and can be used to boot the system for valid MBR it has a value of 55A and hexadecimal when the user switches the system on the CPU sends a power good signal to the motherboard and checks for the computer's bios firmware the BIOS program first evaluates the system hardware and reads the first sector of the hard disk first sector contains MBR Master boot record which has a special program called bootloader bios loads it to the memory and transfers the control to the bootloader at this point the bootloader examines the MBR and looks for the entry of a partition that is marked as active in the partition table the active partition is the partition that the computer will boot from once the bootloader has identified the active partition it searches the hard disk for the very first sector of that partition for a boot record the boot record is a small program that is stored in the first sector of the active partition the boot record is checked for a valid boot signature and if found the booth sector code is loaded into the memory and executed as a program boot record loads the operating system files winload.exe and then OS coloneltos kernel.exe into memory and starts it up once the kernel starts running the Windows loader loads hal.dll boot class device drivers marked as boot start and the system registry Hive into the memory a session manager process is invoked by the kernel to run the boot process and load all the registry hives and drivers necessary for the win32 subsystem to run as a result of the session manager process winlagon.exe is triggered presenting the user login screen for authorization and that's how your computer boots up from the BIOS to the bootloader to the active partition and finally to the boot record all of these pieces working together to start up your computer and get you ready to work or play thanks for watching please subscribe to the channel for future videos and updates

Channel: Computing & Coding

Views: 18,432

Keywords: master boot record, windows 10, mbr partition, windows 7 (operating system), microsoft windows (operating system), repair master boot record (mbr) in windows 10, master boot record live, master boot record personal computer, windows 10 vs windows 11, windows 10 installation step by step, mbr partition table on efi system in hindi, microsoft windows operating system tutorial, Partition table

Id: 1T26DpuKnVs

Length: 4min 24sec (264 seconds)

Published: Mon Feb 20 2023