Activation Process of the BIOS

Activation Process of the BIOS

From the time you press the power source on the master machine to the time when you enter the operating system, the BIOS stored in the mirror EEPROM on the host Board (compact and programmable unique memory) will start to perform the following operations:

1. Initialization:

When the power supply is turned on, the CPU will reset itself to the initial bandwidth for running. BiOS boot block (basically disconnected from the system boot zone) initializes the dynamic block because it is empty at this time, there is no content that can be written, so the operator asks the CPU to retrieve the Reset vector (Reset vector) in the system bios rom ): run the BIOS boot program driver at a fixed position.

Generally, a program records the ffff0h address of a media set, that is, the end of a program in the UMA region. In order to avoid compatibility issues caused by Rom size changes, we usually choose here. Its content only has one jump command, and the next step jumps to the real BIOS animation program. Of course, IBV (independent BIOS vender; independent BIOS providers) can place programs in different locations, as long as they are specified through jump.

During this period, the CPU, chip group, super I/O, and USB of the system are only partially initialized, when you get enough information to handle a BIOS disconnection, you can use the ephemeral disk (controlled by super I/O) even a cd (consisting of chip-based IDE/SATA) and other memory media to rescue the BIOS boot block.

2. Post (power on self test; enable self-tuning ):

Then, the BIOS starts to execute power-on self test (post; enable self-tuning). In the process, check the electronic components and their settings, such: the central processor, the main memory, the mouse, and so on. Then, find the internal display card program built in the bios and click it.

It is usually placed in the c0000h position of the reporter, which is used to initialize the display card, and most of the display cards will show their correlation information on the monitor. This is why when you are on the machine, the alarm card information is displayed in the upper-left corner of the monitor.

Next, let the BIOS look for another preset Rom (only memory player) to see which other BIOS exists in these settings. If any other BIOS is found at this time, it will also be disconnected.

In the next step, the BIOS will show the dynamic interface and start a more in-depth environment, including the memory capacity we can see on the screen. If any response occurs at this time, the Response Message is displayed on the response page.

3. Set the value of the computer system:

There is no end yet. Then, the BIOS will root its own "system data source table" to confirm the system, check whether your computer has installed those system resources or configurations. Some computers will gradually show the devices that have been installed. For example, if the BiOS supports plug-and-play, it will disable and configure plug-and-play devices, and display plug-and-play devices from the BIOS.

After these links, the BIOS will output a summary table on the summary page. In some settings of IBV, this summary table allows users to enable or disable the table. Of course, some IBV just omitted this step for the accelerator.

TIPS: BIOS boot Block

In the quickshield website, it is usually divided into two zones, one of which stores the General BIOS program, that is, the code block used. The other code block stores the program used to start the machine (or first aid, is the enabled boot block ). When the power source is started, the host board will first line from the boot block, it will immediately check whether the code block program is correct, if it is correct, then the code block will continue. The latest BIOS recovery (BiOS back-to-failure) is to use the boot block back-to-source for rescue when BIOS updates are lost.

4. Provide the usual program:

Provides operator systems or medium vector for application calls, such as int 10 h (VGA-shaped and text-spoken.

5. Entry into the operating system:

Here is the part of the system kernel. Next, the BIOS will start searching for the host to change, you can determine the search sequence based on the BIOS settings, currently, frequent on-premise devices include FDD, HDD, optical drive, USB drive, and other devices.

After the host is located, the BIOS will search for the host information to start the Startup Process of the operating system. If you find a hard drive with OS installed, it will be located on the hard drive 0th, 0th bytes, 1st Master Boot Record in the magnetic zone (mainly on the magnetic zone ). If it finds FDD, it will also retrieve the 1st magnetic zone of the dish. Then, place the token in the 7c00h position of the memory, jump there and click it. Since then, we have started to enter the OS segment.