xp start up-windows系统开机启动过程介绍

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2023年12月20日发(作者：)

XP start up

Turn the power to start the machine almost every day computer enthusiasts do, in

the face of an increase on the screen startup screen appears, we will not feel a little

strange, but, the computer display the splash screen when they made some What

work? Some friends believe that it is not clear, this paper to introduce open source

to appear from the blue sky Windows, the computer in the end have done some

things. First, let us know some basic concepts. The first one is very familiar BIOS

(basic input output system), BIOS is dealing directly with the hardware, the

underlying code, which controls the operating system provides the basic functions

of hardware devices. BIOS includes system BIOS (that is often said that the board

BIOS), boot the machine was powered on the computer almost every day lovers do,

the face appears on the screen depicting the splash screen, and we will not feel a

little bit strange, but, the computer screen in the display when they start doing

these work? Some friends believe that it is not clear, this paper to introduce open

source to appear from the blue sky Windows, the computer in the end have done

some things. First, let us know some basic concepts. The first one is very familiar

BIOS (basic input output system), BIOS is dealing directly with the hardware, the

underlying code, which provides control for the operating system, the basic

functions of hardware devices. BIOS includes system BIOS (that is often said that

the board BIOS), video card BIOS and other equipment (such as IDE controllers,

SCSI card, or NIC, etc.) of the BIOS, where the system BIOS is the protagonist of this

paper to discuss, because the computer's startup process is is carried out under its

control. BIOS is generally stored in ROM (read-only memory chip) into, even after

the shutdown or power down, the code will not disappear. The second basic

concept is the memory address, our machines are generally installed 32MB, 64MB

or 128MB of memory, the memory bytes are each given an address for CPU to

access memory. 32MB address range that is the hexadecimal numbers 0 ~

1FFFFFFH, where 0 ~ FFFFFH the low 1MB of memory is very special, because the

original 8086 processor, the maximum memory that can be accessed only 1MB,

1MB which is called the low end of 640KB as the basic memory, A0000H ~ BFFFFH

to be reserved for the graphics card memory to use, C0000H ~ FFFFFH were

reserved for the BIOS to use the system BIOS which generally takes the final 64KB

or a little more space, graphics card BIOS generally C0000H ~ C7FFFH Department,

IDE controller in BIOS C8000H ~ CBFFFH Department. Well, here we take a closer

look at the computer's startup process it.

From the start-up process, since the power to open the operating system in the

start-up screen, this phase of the system BIOS from the control of the master, then

it in this process have been completed and what work it »said there are two major

areas : Booting the system and self-inspection system since the move. BIOS code in

fact most of the hardware and testing of the system, these procedures were

implemented after reading the CPU process, we call the POST (Power On Self Test:

power-self-test). Computer hardware design is perfect self-checking mechanism, in

that brief few seconds, can be completed up to hundreds of Procedure. If the

self-inspection went smoothly, BIOS will be responsible for loading the operating

system boot. In particular, BIOS boot start of the work flow can be briefly described

as follows: B

Step One: When we press the power switch, power supply began to supply to the

motherboard and other devices, when the voltage is also less stable, the control on

the motherboard chipset will be sent to the CPU and maintain a RESET (reset) signal,

Let the internal CPU automatically returns to the initial state, but the CPU will not

immediately execute instructions at the moment. When the chip set to power has

already begun testing the stability of power supply (of course, the process from

unstable to stable things only a brief moment), it will removed the RESET signal (if it

is manually press the Reset button on the computer panel to restart the machine,

then release the button will be removed when the RESET signal chipset), CPU

immediately started from the address FFFF0H at the instruction from the preceding

description is known, the address is actually in the system BIOS address range,

whether it is Award BIOS or AMI BIOS , on the instruction here is just a jump, jump

to the system BIOS boot code in the real place.

Step two: the system BIOS boot code first thing to do is to POST (Power-On Self

Test, self-test after power on), POST's main task is to test the system and the

existence of some critical equipment can work properly, such as memory and

graphics cards and other equipment. Since POST is a pioneer in the testing process,

this time not initialize graphics card, if the system BIOS during the POST process

discovered some fatal error, for example, did not find a problem with memory or

memory (640K of conventional memory at this time only check ), then the system

BIOS will control the speaker sound directly to report errors, the length and

frequency of the sound represents the type of error. Under normal circumstances,

POST process is very fast, we can hardly feel its presence, POST will be called after

other code to a more complete hardware detection.

Step Three: Next, the system BIOS looks for the graphics card BIOS, as I said before,

stored in the ROM BIOS chip card start address is usually located in the C0000H

Department, the system BIOS to find in this place call it after the video card BIOS

initialization code to initialize the graphics card BIOS, then the majority of graphics

on the screen will show some initial information, introduce manufacturers, graphics

chip type, etc., but this picture is almost flashed. System BIOS will then find the

BIOS program other devices to find the same to call them after the BIOS

initialization code to initialize the internal related equipment.

Step four: After all the other equipment to find BIOS, the system BIOS will show its

own splash screen, which included the type of system BIOS, serial number and

version number and so on.

Step Five: Then the system BIOS will detect and display the type and frequency of

CPU, and then began to test all the RAM, and also displayed on the screen memory

test in progress, we can decide in the CMOS settings or use a simple little

time-consuming time-consuming and more detailed testing methods.

Step Six: Memory test passed, the system BIOS will begin testing some of the

standard installed on the system hardware, including hard drives, CD-ROM, serial,

parallel, floppy and other equipment, while most of the newer version of the

system BIOS in this a process also automatically detect and set the memory timing

parameters, drive parameters and access modes.

Step Seven: Standard equipment testing is completed, the system supports Plug

and Play BIOS code inside will begin to detect and configure Plug and Play devices

installed in the system, each find a device, the system BIOS will be displayed on the

screen device name and model number and other information, while the device is

assigned an interrupt, DMA channels and I / O ports and other resources.

Step Eight: At this point so far, have been detected all the hardware configuration is

completed, the majority of the system BIOS will re-clear the screen and top of the

screen shows a table that briefly lists the various standard installed on the system

hardware, and their use of resources and some of the relevant operating

parameters.

Step Nine: The next system will update the BIOS ESCD (Extended System

Configuration Data, extended system configuration data). ESCD is the system BIOS

and operating system used to exchange as a means of hardware configuration

information, the data is stored in the CMOS (a small piece of special RAM, the

battery on the motherboard to power supply) into. ESCD data is usually only after

the system hardware configuration changes to be updated, so it is not every time

you start the machine when we are able to see the "Update ESCD ... Success" such

information, however, some motherboards system BIOS ESCD data is saved with

Windows 9x does not use the same data format, so Windows 9x startup process in

its own data in the ESCD will change into their own format, but the next time you

start the machine, even if the hardware configuration has not changed, the system

BIOS will be the ESCD data format change back, and so on, will cause every time

you start the machine, the system BIOS must be updated again ESCD, which is why

some machines in each startup will display information about the reasons.

Step Ten: ESCD update is completed, the system BIOS boot code will be its final

task, that is, the boot sequence specified by the user from a floppy disk, hard disk

or CD-ROM to start.

To start from the C drive, for example, the system BIOS will read and execute on the

hard disk master boot record, master boot record partition table and then to find

from the first active partition, and then read and execute the active partition of the

partition boot record, and read the partition boot record and will be responsible for

the implementation of , which is the most basic DOS and Windows 9x system

files. Windows 9x's first initialize some important system data, and then to

show the familiar blue and white, in this picture below, Windows will continue to be

part and DOS GUI (graphical user interface) portion of the guide and initialization.

If the system is being installed in multiple operating system boot tools, usually the

master boot record will be replaced with the guidance of the software code that

will allow the user to choose an operating system, and then read and execute the

operating system's basic Boot code (DOS and Windows, basic boot code is the

partition boot record).

Described above is the computer power switch (or press the Reset button) when

the cold start initialization to complete all work in DOS, if we press Ctrl Alt Del key

combination (or from Windows, select Restart the computer ) to the hot start, then

the POST process will be skipped, starting directly from the third step, another step

in the detection of the fifth test the CPU and memory will no longer be. We can see

that both the cold start or warm start, the system BIOS are repeated over and over

again, and these we usually do not pay attention to things, but it is these

monotonous hardware detection step for us to be able to provide normal use of

the computer foundation.

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