Bootstrapping

• The process of initializing the computer and loading the operating system is known as bootstrapping. This usually occurs when the computer is powered-up or reset.
• The initial loading is done by a small program that usually resides in non-volatile memory (e.g., EPROM). This in turn loads the OS from an external device.
• Once loaded, how does the operating system know what to do next? It waits for some event to occur: e.g., the user typing a command on the keyboard.
• During ``normal'' operations of a computer system, some portions of the operating system remain in main memory to provide services for critical operations, such as dispatching, interrupt handling, or managing (critical) resources.
• These portions of the OS are collectively called the kernel.

Kernel = OS - transient components
remains comes and goes

Figure 1.14: UNIN System initilization