Large hard disk and WIN8 system, let us upgrade from the traditional BIOS+MBR mode to UEFI+GPT mode . The mainstream computers we buy now are all pre-installed with WIN8 system. In order to better support 2TB hard disks, start win8 more quickly. The installed system has adopted the GPT partition format, and the motherboard bios supports UEFI boot.
Here is a brief explanation of these proper nouns:
One, BIOS
The so-called BIOS is actually the basic input-output system (Basic Input-Output System) of the microcomputer. Its content is integrated on a ROM chip on the motherboard of the microcomputer . It mainly stores the most important basic input and output programs and system information settings of the microcomputer system. , Power-on self-check program and system startup boot program, etc. The BIOS setup program mainly manages and configures the computer's basic input and output system to make the system run in the best state. Using the BIOS setup program can also troubleshoot or diagnose system problems . Some people think that since BIOS is a "program", it should belong to software, and it feels like Word or Excel. But many people don't think so, because it is still somewhat different from general software, and its connection with hardware is quite close . To put it vividly, BIOS should be a " bridge " connecting software programs and hardware devices , and is responsible for solving the immediate requirements of the hardware .
The configuration record of the microcomputer components is placed in a readable and writable CMOS RAM chip , which mainly saves the basic information of the system, CPU characteristics, soft and hard drives, displays, keyboards and other components . The CMOS RAM chip is powered by the system through a back-up battery, and the CMOS information will not be lost whether it is in the shutdown state or when the system is powered off. A " system setup program " is installed in the BIOS ROM chip , which is mainly used to set various parameters in the CMOS RAM . This program can enter the setting state by pressing a certain key when starting up, and provides a good interface for the operator to use. In fact, this process of setting CMOS parameters is also called "BIOS setup" in habit. Once the configuration information about the microcomputer in the CMOS RAM chip is incorrect, the lighter one will reduce the overall system operating performance, the soft and hard disk drive and other components will not be recognized, and the serious one will cause a system's software and hardware failures.
Two, MBR
The main boot record (MBR, Main Boot Record) is a section of boot code (grub) located at the forefront of the disk . It is responsible for judging the legitimacy of the partition when the disk operating system (DOS) reads and writes the disk , and locates the partition boot information. It is generated by the Disk Operating System (DOS) when the hard disk is initialized, that is, the partition program (such as Fdisk) is generated. It does not depend on any operating system, and the hard disk boot program can also be changed to achieve multi-system coexistence.
The master boot sector is composed of three parts (a total of 512 bytes), the master boot program is the master boot record (MBR) (occupies 446 bytes), located on the hard disk 0 cylinder, 0 head, 1 sector, It can be found in the FDISK program, which is used to transfer system control to a certain operating system specified by the user and registered in the partition table when the hard disk is started. Disk Partition Table (DPT, Disk Partition Table) consists of four partition table entries (16 bytes each). The end flag (occupying 2 bytes), its value is AA55, when storing, the low bit is in front and the high bit is in the back, that is, it looks like 55AA (hexadecimal).
Three, GPT
GPT (GUID Partition Table) is called GUID partition table (GUID-Unique Identifier for the entire region), which is a globally unique identification partition table . This is a new standard that is gradually replacing MBR. It complements UEFI---UEFI is used to replace the old BIOS, and GPT is used to replace the old MBR. This standard does not have those restrictions of MBR. Disk drive capacity can be much larger. It also supports almost unlimited number of partitions, the limitation is only in the operating system, Windows supports up to 128 GPT partitions. Through UEFI, all 64-bit systems can boot from GPT.
The first sector of the GPT disk also has a mark similar to the MBR (Master Boot Record), called PMBR . The function of PMBR is that when using a partition tool that does not support GPT, the entire disk will be displayed as a protected partition to prevent the partition table and disk data from being damaged. And the content stored in it is the same as MBR.
Comparison of GPT and MBR:
- The mbr supports up to 2T, and the gpt format supports up to 18EB of large capacity. 1EB=1024PB, 1PB=1024 TB, so gpt is theoretically unlimited.
- MBR means "Master Boot Record", and GPT means GUID Partition Table, that is, "Globally Unique Identifier Disk Partition Table".
- mbr supports up to four primary partitions, and gpt has no restrictions. Win7 can only use mbr partition (also possible, but not recommended), starting from Win8, Microsoft recommends using gpt.
- If the hard disk exceeds 2T, then GPT UEFI must be selected, and it does not matter if it is below 2T.
Four, GRUB
GNUB (GRand Unified Bootloader) is a multi-operating system startup program from the GNU project . GRUB is an implementation of the multi-boot specification, which allows users to have multiple operating systems in the computer at the same time, and select the operating system they want to run when the computer starts. GRUB can be used to select different kernels on the operating system partition, and it can also be used to pass startup parameters to these kernels . It is a multi-operating system boot manager , used to boot different systems, such as windows, Linux.