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BIOS
Computer's boot process is carried out under the control of the motherboard BIOS, the BIOS is also known as the "System BIOS", its content in a particular area of the south bridge chip CMOS battery on the motherboard it is to save the information and provide power CMOS of. In addition to this, "the system the BIOS", each PCI device may also provide their own the BIOS, their function is direct access to the device where the PCI configuration registers to obtain information PCI device, the configuration parameters of PCI devices, to complete the initialization PCI devices and the like .
three phases:
- Pown On: power from the front to the screen message appears. The main task is to check the correctness of the contents of the CMOS
- POST (Power On Self Test): Check the key equipment (such as graphics, memory) if it works
- Loading Bootloader: all hardware is normal, the master boot sector is loaded and executed in the Bootloader
Bootloader
Bootloader is the first piece of code embedded system power-executed code initializes cpu and related hardware resources, and ultimately the kernel boot loader, boot other operating systems. Bootloader finished booting the kernel, resource operation rights will be handed over to the kernel, then the kernel like a never-quit while (1) loop is executed with.
Operating system hierarchy
Core layer: Direct written reference hardware specifications, so the same core can not be run on different hardware architecture
system call: a set of development interface provides the core layer up for the high-level language use
The main function of the operating system
The main function of the operating system
- Providing system call interfaces
- Processor Management
- Memory Management
- File System Management
- Device Management
