BIOS

 what is BIOS?

  The primary function of the BIOS is to identify and initiate component hardware (such as hard disk, floppy and optical disk drives). This is to prepare the machine so other software programs stored on various media can load, execute, and assume control of the PC.[3] This process is known as booting, or booting up, which is short for bootstrapping.
  BIOS can also be said to be a coded program embedded on a chip that recognizes and controls various devices that make up x86 personal computers. Among other classes of computers, the generic terms boot monitor, boot loader or boot ROM were commonly used. Some Sun and Macintosh PowerPC computers used Open Firmware for this purpose. There are a few proposed alternatives for Legacy BIOS in the x86 world: Extensible Firmware Interface, Open Firmware (used on the OLPC XO-1) and coreboot.

  The term first appeared in the CP/M operating system, describing the part of CP/M loaded during boot time that interfaced directly with the hardware (CP/M machines usually had a simple boot loader in ROM, and nothing else). Most versions of DOS have a file called "IBMBIO.COM" or "IO.SYS" that is analogous to the CP/M disk BIOS.

  注释：BIOS的主要功能是识别和初始化硬件设备，是为了使得存储在各种媒介上的软件程序能够被加载、运行。这过程称为启动。BIOS只存在于X86体系结构的计算机，在其他类型的计算机，常用的通用的术语有：boot monitor,boot loader。

 

BIOS包含输入输出例行程序的扩展集以及系统设备状态表。操作系统和用户程序都可以请求BIOS例程与系统连接的设备进行通信。和BIOS接口的方法是调用软件中断。

                           --《IBM PC 汇编语言程序设计》