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This article is to share with you about the principle of computer startup. The editor thought it was very practical, so I shared it with you as a reference. Let's follow the editor and have a look.

The first stage of computer startup is to initialize the hardware. Before 2000, BIOS was used on the computer motherboard. Today, the vast majority of computers use EFI (Mac uses EFI) or UEFI,BIOS is being phased out. The boot process based on EFI and UEFI is different from that of traditional BIOS. From the following figure, we can see that UEFI boot has one less link of "BIOS self-test" than traditional BIOS, which greatly reduces the boot speed of UEFI boot; UEFI loads the operating system directly from the pre-boot environment, thus saving boot time.

What is BIOS?

BIOS is an acronym for "Basic Input Output System". After literal translation, the Chinese name is "basic input and output system". In fact, it is a group of programs solidified on a ROM chip on the motherboard in the computer, which stores the computer's most important basic input and output programs, system setting information, post-boot self-test program and system self-startup program. Its main function is to provide the lowest and most direct hardware setting and control for the computer.

What are EFI and UEFI?

EFI is the abbreviation of Extensible Firmware Interface (Extensible firmware Interface). It is an upgrade scheme advocated by Intel to replace BIOS in PC-like systems. Compared with the traditional BIOS, EFI constructs the system through modularization, parameter stack transfer of C language and dynamic link, which is easier to implement and has stronger fault tolerance and correction characteristics than BIOS. UEFI is Unified Extensible Firmware Interface (Unified Extensible firmware Interface), which is based on the EFI 1.10 standard, but is not owned by Intel, but by an international organization called Unified EFI Form. UEFI is a standard that details the type interface and allows PC to be loaded into the operating system from a pre-started operating environment. Since the EFI 1.02 standard was officially released on December 12, 2000, EFI has been existing as an advanced standard to replace the traditional BIOS, and the ownership is in the hands of Intel. From 2007, Intel handed over the improvement and improvement of the EFI standard to Unified EFI Form for full responsibility, and then the EFI standard was officially renamed UEFI to show the difference.

The hard drive booted from UEFI must be in GPT format and must be a win 7-8-10 64 system. UEFI does not support 32-bit systems. Uefi and legacy (traditional meaning) are two different ways to boot, uefi is the new BIOS,legacy is the traditional BIOS.

The hard drive started by UEFI must be in GPT format, so what is GPT?

You must partition the new disk before using it. MBR (Master Boot Record) and GPT (GUID Partition Table) are two different ways to store partition information on disk. This partition information contains information about where the partition starts so that the operating system knows which sector belongs to which partition and which partition is bootable. When creating partitions on disk, you have to choose between MBR and GPT.

What is MBR?

MBR, which means "master boot record", was first proposed in IBM PC DOS 2.0 in 1983. The "master boot record" is called because it is a special boot sector that exists at the beginning of the drive. This sector contains logical partition information for boot loaders and drives of installed operating systems. The so-called boot loader is a small piece of code used to load larger loaders on other partitions on the drive. If you have installed the Windows,Windows boot loader, the initial information is placed in this area-if the MBR information is overwritten and Windows cannot be started, you will need to use Windows's MBR repair feature to get it back to normal. If you install Linux, the GRUB loader is usually located in MBR. MBR supports maximum 2TB disks and cannot handle disks larger than 2TB capacity. MBR also supports up to 4 primary partitions-if you want more partitions, you need to create so-called "extended partitions" and create logical partitions in them. MBR has become the industry standard for disk partitioning and booting.

What is GPT?

GPT means GUID partition table. (GUID means globally unique identifier). This is a new standard that is gradually replacing MBR. It and UEFI complement each other-UEFI is used to replace the old BIOS, while GPT replaces the old MBR. It is called a "GUID partition table" because each partition on your drive has a globally unique identifier (globally unique identifier,GUID)-a randomly generated string that ensures that every GPT partition on the planet is assigned a completely unique identifier. This standard does not have the limitations of MBR. Disk drive capacity can be much larger than the operating system and file system can support. It also supports an almost unlimited number of partitions, limited only to the operating system-Windows supports up to 128GPT partitions, and you don't need to create extended partitions. On MBR disks, partition and boot information are saved together. If this part of the data is overwritten or destroyed, things will be in trouble. In contrast, GPT keeps multiple copies of this information on the entire disk, so it is more robust and can recover the corrupted information. GPT also keeps cyclic redundancy check codes (CRC) for this information to ensure its integrity and correctness-if the data is corrupted, GPT will detect the corruption and recover it from elsewhere on disk. On the other hand, there is nothing MBR can do about these problems-it is only after the problem occurs that you will find that the computer cannot be started, or the disk partition is missing.

We recommend that you use GPT to partition the disk. It is more advanced, more robust, and all computer systems are moving to it. If you need to maintain compatibility with older systems-such as starting Windows on computers that use traditional BIOS-you need to use MBR.

About the computer startup principle to share here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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