Analysis of what role and function of win7 system BIOS settings and CMOS settings

What is BIOS?

The so-called BIOS is actually the basic input-output system of the microcomputer. Its content is integrated on a ROM chip on the motherboard of the microcomputer. It stores the most important basic input and output programs for the microcomputer system, system information setting, power-on self-test program and system startup bootloader.

BIOS Utility

The BIOS ROM chip can be seen not only on the motherboard, but also how the BIOS management function determines the performance of the motherboard to a large extent.

1, BIOS interrupt service program

BIOS interrupt service program is essentially a programmable interface between software and hardware in the microcomputer system, mainly used between the program software and the computer hardware Achieve convergence. For example, the management of peripheral devices such as floppy disks, hard disks, optical drives, keyboards, monitors, etc. in DOS and Windows operating systems is based directly on the BIOS system interrupt service program, and operators can also access INT 5, INT 13 Wait for the interrupt point and directly call the BIOS interrupt service routine.

2, BIOS system setup program

Microcomputer component configuration record is placed in a readable and writable CMOS RAM chip, mainly to save the basic situation of the system, CPU characteristics, soft hard drive, Information on components such as monitors and keyboards. The BIOS ROM chip is equipped with a system setting program, which is mainly used to set various parameters in the CMOS RAM. This program presses a specific button at boot time to enter the setup state and provides a good interface for the operator to use. In fact, this process of setting CMOS parameters is also known as ” BIOS settings & rdquo;. Once the configuration information about the microcomputer in the CMOS RAM chip is incorrect, the light system will reduce the overall running performance of the system, and the components such as the soft hard disk drive will not be recognized. In severe cases, a system hardware and software failure will be caused.

3, POST power-on self-test

After the microcomputer is powered on, the system first checks the internal devices by the POST (Power On Self Test) program. Usually the complete POST self-test will include testing the CPU, 640K basic memory, 1M or more expansion memory, ROM, motherboard, CMOS memory, serial parallel port, display card, soft hard disk subsystem and keyboard, once in self-test If a problem is found, the system will give a prompt or a whistle warning.

4, BIOS system bootloader

After the system completes the POST self-test, the ROM BIOS first searches for the soft hard disk drive and CD-ROM according to the boot sequence saved in the system CMOS settings. The network server or the like effectively starts the drive, reads in the operating system boot record, and then gives the system control to the boot record, and the boot record completes the smooth start of the system.

What is CMOS?

CMOS (meaning that it is a complementary metal oxide semiconductor memory device, which is a large-scale application for integrated circuit chip manufacturing) is a piece of computer motherboard. The RAM chip for reading and writing is mainly used to save the hardware configuration of the current system and the setting of certain parameters by the operator. The CMOSRAM chip is powered by the system through a backup battery, so the CMOS information will not be lost whether it is in the off state or in the event of a system power failure.

Since the CMOSRAM chip itself is only a memory and only has the function of saving data, the setting of various parameters in CMOS is through a special program. Early CMOS setup programs resided on floppy disks (such as IBM's PC/AT models) and were inconvenient to use. Most manufacturers now implement the CMOS setup program in the BIOS chip. It is very convenient to set the CMOS setup program by pressing a specific button at boot time. This CMOS setup is usually called BIOS setup.

The difference between BIOS setup and CMOS setup

The BIOS is an EPROM or EEPROM chip on the motherboard, which contains important information about the system and the setup procedure for setting system parameters (BIOSSetup program). CMOS is a readable and writable RAM chip on the motherboard, which contains specific parameters about the system configuration, and its contents can be read and written by setting the program. The CMOSRAM chip is powered by a backup battery, and the information is not lost even after the system is powered down. The BIOS and CMOS are both related and different: the system setting program in the BIOS is the means to complete the CMOS parameter setting; the CMOS RAM is both the storage location of the BIOS setting system parameters and the result of the BIOS setting system parameters. Therefore, the complete statement should be "set the CMOS parameters through the BIOS setup program". Since both BIOS and CMOS are related to the system settings, the BIOS settings and CMOS settings are actually used in the actual use process. In fact, they all refer to the same thing, but BIOS and CMOS are two completely different concepts. Do not confuse.

When do you want to set the BIOS or CMOS?

It is well known that BIOS or CMOS settings are a very important system initialization work performed manually by the operator based on the actual situation of the microcomputer. In the following cases, BIOS or CMOS settings must be made:

1. Newly purchased microcomputer

Even a system with PnP function can only identify a part of the microcomputer peripherals, but the parameters of the soft disk. The basic data such as the current date and clock must be set by the operator. Therefore, the newly purchased microcomputer must tell the system the basic configuration of the entire microcomputer by setting the CMOS parameters.

2. Adding a device

Since the system does not necessarily recognize the new device, it must be told by the CMOS settings. In addition, once an IRQ or DMA conflict occurs between the newly added device and the original device, it is often necessary to perform the exclusion through the BIOS setting.

3. CMOS data accidental loss

In the case of system backup battery failure, virus damage CMOS data program, accidentally clearing CMOS parameters, etc., CMOS data is often accidentally lost. At this point, you can only re-enter the BIOS setup program to complete the new CMOS parameter settings.

4. System optimization

For memory read and write waiting time, hard disk data transmission mode, use of internal/external Cache, energy saving protection, power management, boot sequence, etc. The settings are not necessarily optimal for the system, and often require multiple trials to find the best combination of system optimizations.