Many people are talking about the fact that Bios and cmos are always confused. In fact, there is a difference between the two. What are the differences? First, we must know: What is Bios and what is cmos? The following is a quick start to Xiaobian for detailed answers.
What is the 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 mainly stores the most important basic input and output programs for the microcomputer system. System information setting , power-on self-test program and system bootloader.
The function of the BIOS, the BIOS ROM chip can be seen not only on the motherboard, but also how the BIOS management function largely determines whether the motherboard performance is superior. BIOS management functions mainly include:
1. BIOS interrupt service program, BIOS interrupt service program is essentially a programmable interface between software and hardware in the microcomputer system, mainly used to achieve the connection between the program software and the microcomputer hardware. 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 setting program, the microcomputer component configuration record is placed in a readable and writable CMOS RAM chip, which mainly stores the basic information of the system, CPU characteristics, soft hard disk drive, display, keyboard and other components. The "system setting program" is installed in the BIOS ROM chip, 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 setup". 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 connected to the power supply, 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. The BIOS system starts the bootloader. After the system completes the POST self-test, the ROM BIOS first searches for the soft hard disk drive, the CD-ROM, the network server, etc. according to the boot sequence saved in the system CMOS settings, and effectively starts the drive, and reads the operation. The system boots the record, then passes the system control to the boot record, and the boot record completes the smooth start of the system.
What is CMOS?CMOS (intended to mean complementary metal oxide semiconductor memory, a large-scale application of integrated circuit chip manufacturing) is a readable and writable RAM chip on the motherboard of the computer, mainly used to save the current system hardware configuration and The operator's setting of certain parameters. The CMOS RAM 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 CMOS RAM chip itself is only a memory and only has the function of saving data, the setting of various parameters in the 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 BIOS is an EPROM or EEPROM chip on the motherboard, which contains important information of the system and a setting program for setting system parameters (BIOS Setup program); CMOS is a readable and writable RAM chip on the motherboard, which is installed on the system. The specific parameters of the configuration can be read and written by the setup program. The CMOS RAM chip is powered by a backup battery, and the information is not lost even after the system is powered down. 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 "setting 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.
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. BIOS or CMOS settings must be made in the following cases:
1. Newly purchased microcomputers, even systems with PnP function can only identify a part of microcomputer peripherals, and the basic data such as soft disk parameters, current date, clock, etc. must be set by the operator, so the newly purchased microcomputer must pass The CMOS parameter settings tell the system the basic configuration of the entire microcomputer.
2. Add a new device. Since the system does not necessarily recognize the newly added 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 is accidentally lost. In the case of system backup battery failure, virus destroying 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 preset settings in the BIOS are not necessarily the most for the system. Excellent, at this time often requires a lot of trials to find the best combination of system optimization.
to sum up BIOS and CMOS are both related and different. The system setting program in BIOS is the means to complete CMOS parameter setting; CMOS is both the BIOS setting system parameter storage place and the result of BIOS setting system parameters.
The above is the relationship and difference between BIOS and CMOS. If there is something imperfect, please advise.
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