What is Bios and CMOS

　　在日常操作和维护计算机的过程中，常常可以听到有关BIOS设置和CMOS设置的一些说法，许多人对BIOS和CMOS经常混为一谈。本文主要阐述对BIOS设置和CMOS设置在基本概念上的区分与联系。 　　

　　BIOS是什么?

　　所谓BIOS，实际上就是微机的基本输入输出系统（Basic Input－Output System），其内容集成在微机主板上的一个ROM芯片上，主要保存着有关微机系统最重要的基本输入输出程序，系统信息设置、开机上电自检程序和系统启动自举程序等。

　　BIOS的功用

　　BIOS ROM芯片不但可以在主板上看到，而且BIOS管理功能如何在很大程度上决定了主板性能是否优越。BIOS管理功能主要包括： 　　

　　1． BIOS中断服务程序

　　BIOS中断服务程序实质上是微机系统中软件与硬件之间的一个可编程接口，主要用来在程序软件与微机硬件之间实现衔接。例如，DOS和Windows操作系统中对软盘、硬盘、光驱、键盘、显示器等外围设备的管理，都是直接建立在BIOS系统中断服务程序的基础上，而且操作人员也可以通过访问INT 5、INT 13等中断点而直接调用BIOS中断服务程序。 　　

　　2．BIOS系统设置程序

　　微机部件配置记录是放在一块可读写的 CMOS RAM 芯片中的，主要保存着系统基本情况、CPU特性、软硬盘驱动器、显示器、键盘等部件的信息。在 BIOS ROM芯片中装有"系统设置程序"，主要用来设置CMOS RAM中的各项参数。这个程序在开机时按下某个特定键即可进入设置状态，并提供了良好的界面供操作人员使用。事实上，这个设置CMOS参数的过程，习惯上也称为" BIOS设置"。一旦CMOS RAM芯片中关于微机的配置信息不正确时，轻者会使得系统整体运行性能降低、软硬盘驱动器等部件不能识别，严重时就会由此引发一系统的软硬件故障。

　　3． POST上电自检

　　微机按通电源后，系统首先由POST（Power On Self Test,上电自检)程序来对内部各个设备进行检查。通常完整的POST自检将包括对 CPU、640K基本内存、 1M以上的扩展内存、ROM、主板、CMOS存贮器、串并口、显示卡、软硬盘子系统及键盘进行测试，一旦在自检中发现问题，系统将给出提示信息或鸣笛警告。 　　

　　4． BIOS系统启动自举程序

　　系统在完成 POST自检后， ROM BIOS 就首先按照系统 CMOS设置中保存的启动顺序搜寻软硬盘驱动器及CD-ROM、网络服务器等有效地启动驱动器，读入操作系统引导记录，然后将系统控制权交给引导记录，并由引导记录来完成系统的顺利启动。

　　CMOS是什么?

　　CMOS(本意是指互补金属氧化物半导体存储嚣，是一种大规模应用于集成电路芯片制造的原料)是微机主板上的一块可读写的RAM芯片，主要用来保存当前系统的硬件配置和操作人员对某些参数的设定。CMOS RAM芯片由系统通过一块后备电池供电，因此无论是在关机状态中，还是遇到系统掉电情况，CMOS信息都不会丢失。

　　由于CMOS RAM芯片本身只是一块存储器，只具有保存数据的功能，所以对CMOS中各项参数的设定要通过专门的程序。早期的CMOS设置程序驻留在软盘上的(如IBM的PC/AT机型)，使用很不方便。现在多数厂家将CMOS设置程序做到了 BIOS芯片中，在开机时通过按下某个特定键就可进入CMOS设置程序而非常方便地对系统进行设置，因此这种CMOS设置又通常被叫做BIOS设置。

　　BIOS设置和CMOS设置的区别与联系

　　BIOS是主板上的一块EPROM或EEPROM芯片，里面装有系统的重要信息和设置系统参数的设置程序（BIOS Setup程序)；CMOS是主板上的一块可读写的RAM 芯片，里面装的是关于系统配置的具体参数，其内容可通过设置程序进行读写。CMOS RAM 芯片靠后备电池供电，即使系统掉电后信息也不会丢失。BIOS与CMOS既相关又不同：BIOS中的系统设置程序是完成CMOS参数设置的手段；CMOS RAM既是BIOS设定系统参数的存放场所，又是 BIOS设定系统参数的结果。因此，完整的说法应该是"通过BIOS设置程序对CMOS参数进行设置"。由于 BIOS和CMOS都跟系统设置密初相关，所以在实际使用过程中造成了BIOS设置和CMOS设置的说法，其实指的都是同一回事，但BIOS与CMOS却是两个完全不同的概念，千万不可搞混淆。

　　何时要对BIOS或CMOS进行设置？

　　众所周知，进行BIOS或CMOS设置是由操作人员根据微机实际情况而人工完成的一项十分重要的系统初始化工作。在以下情况下，必须进行BIOS或CMOS进行设置：

　　1、新购微机

　　即使带PnP功能的系统也只能识别一部分微机外围设备，而对软硬盘参数、当前日期、时钟等基本资料等必须由操作人员进行设置，因此新购买的微机必须通过进行CMOS参数设置来告诉系统整个微机的基本配置情况。

　　2．新增设备

　　由于系统不一定能认识新增的设备，所以必须通过CMOS设置来告诉它。另外，一旦新增设备与原有设备之间发生了IRQ、DMA冲突，也往往需要通过BIOS设置来进行排除。

　　3．CMOS数据意外丢失

　　在系统后备电池失效、病毒破坏了 CMOS数据程序、意外清除了CMOS参数等情况下，常常会造成CMOS数据意外丢失。此时只能重新进入BIOS设置程序完成新的CMOS参数设置。

　　4．系统优化

　　对于内存读写等待时间、硬盘数据传输模式、内／外 Cache的使用、节能保护、电源管理、开机启动顺序等参数， BIOS中预定的设置对系统而言并不一定就是最优的，此时往往需要经过多次试验才能找到系统优化的最佳组合。

In the day-to-day operation and maintenance of the computer in the process, we often hear the BIOS settings and some of that CMOS settings, many people often confuse the BIOS and CMOS. This paper elaborated on the CMOS setup and BIOS installed in the basic concept of the distinction and contacts. 　　

BIOS?

The so-called BIOS is, in fact, the computer basic input output system (Basic Input-Output System), which integrated PC motherboard in a ROM chip, the main computer system preserved the most important basic input-output process, system information set , on the boot, self-inspection procedures and systems start bootstrap procedures.

BIOS function

BIOS ROM chip on the motherboard can see, and how the BIOS management board determine to a large extent whether the superior performance. BIOS management features include:

1. BIOS interrupt service routine

BIOS interrupt service routine is essentially in the computer software and hardware system between a programmable interface, used primarily in the computer hardware and software to achieve convergence between. For example, DOS and Windows operating system on floppy disks, hard drives, CD drives, keyboards, monitors and other peripherals management are directly in the system BIOS interrupt service on the basis of procedures, and operators can also visit INT 5, INT 13 breakpoint in such a direct call BIOS interrupt service routine. 　　

2. System BIOS setup program

Computer records are configured components can read and write on a CMOS RAM chips, mainly the preservation of the basic system, CPU features, soft hard drives, monitors, keyboards and other components of information. In the BIOS ROM chip that is equipped with a "system set up procedures" are mainly used for CMOS RAM settings in the various parameters. This procedure in a particular boot press button access settings, and provide a good interface for the operator to use. In fact, this parameter settings CMOS process, and habits, also known as "the BIOS settings." Once CMOS RAM chip on the computer's configuration information is not correct, they will make light system to reduce overall operating performance, hard disk drives and other soft parts can not be identified, this will trigger serious when a system of hardware and software failures.

3. POST self-checking power

Computer-by power, the system first by the POST (Power On Self Test, a power-on self test) of the internal procedures to inspect all equipment. POST usually integrity of the self-inspection will include CPU, memory basic 640K, 1M more extended memory, ROM, motherboards, CMOS memory, serial parallel port, cards, soft keyboard and hard disk subsystem testing, once in the self-inspection discovering problems in the system will give messages or warning whistle. 　　

4. BIOS boot bootstrap procedures

POST completed self-inspection system, the ROM BIOS in accordance with the system on the first CMOS settings stored in the boot sequence search soft hard drives and CD-ROM, network servers, effectively launching drives, read the operating system boot record, and then control system to the boot record, guided by the system records to complete a smooth start.

CMOS?

CMOS (intent is complementary metal oxide semiconductor memory嚣, is a large-scale integrated circuit chips used in the manufacture of raw materials) is a computer on the motherboard RAM chips can read and write, mainly to preserve the current system's hardware configuration and operation on the staff of some of the parameters set. CMOS RAM chip by the system through a battery backup power supply, so whatever is in the off state, or brownout situation in the event of systems, CMOS information is not lost.

As CMOS RAM chip itself is only a memory, only with the function of preserving data, the parameters of the CMOS settings through special procedures. The early presence in the CMOS setup program on the diskette (such as the IBM PC / AT models), use very convenient. Most manufacturers now CMOS setup program will be a BIOS chip, in the boot through a specific button can be pressed into the CMOS setup program and very easy to set up the system, this CMOS settings usually called the BIOS settings.

BIOS settings and CMOS settings associated with the distinction

BIOS on the motherboard is an EPROM or EEPROM chip inside the system with important information and set up procedures for setting system parameters (BIOS Setup program); CMOS is the one on the motherboard RAM chips can read and write, is installed inside the system the specific configuration parameters, and its content can be read and write by setting procedures. CMOS RAM chip on battery backup power supply, even after brownout information system will not be lost. BIOS and CMOS both relevant and different: the system BIOS Setup for the completion of the CMOS parameter setting means CMOS RAM is a system parameter settings BIOS storage sites, BIOS settings is the result of system parameters. Therefore, the integrity of the argument should be "through the BIOS settings on the CMOS process parameters set." Due to BIOS and CMOS told of the beginning of the relevant system settings, in the actual process in the use of the CMOS setup and BIOS settings that, in fact refer to the same thing, but the BIOS and CMOS is two totally different concepts. must not engage in confusion.

When to carry out the BIOS or CMOS settings?

As we all know, a BIOS or CMOS settings by computer operators in accordance with the actual situation and the completion of a very important system initialization work. In the following circumstances, the need for BIOS or CMOS settings:

1, the newly purchased computer

Even with PnP functional system can only identify part of Computer peripherals, and hard disk parameters of the soft, the current date, the clock, and other basic information must be set by the operator, the new computer must be purchased through CMOS parameter settings to tell System the basic configuration of the computer.

2. New equipment

The system may not be able to understand the new equipment, must be approved CMOS settings to tell it. In addition, once the new equipment and existing equipment between the IRQ, DMA conflict, but also often need to rule out the BIOS settings.

3. CMOS data accidental loss

Backup battery failure in the system, the virus destroyed the CMOS data procedures, the accident cleared CMOS parameters Under such circumstances, often causing accidents CMOS data loss. At this point only to re-enter the BIOS setup program to fulfill the new CMOS parameter settings.

4. System Optimization

Waiting time for reading and writing of memory, hard disk data transfer mode, the inner / outer Cache the use of energy-saving protection, power management, boot the boot sequence, and other parameters in the BIOS settings on the target systems is not necessarily the best, when often After several tests need to find the best combination of system optimization.