What is required to refresh a computer after switch on the computer?

Answer 1

When a computer is switched on, it begins by executing instructions stored permanently in ROM. These startup instructions do some self-testing, configuring, and device initialization, and is called the BIOS. The BIOS will load into memory the next set of startup instructions, called the boot loader, which is found in the startup device stored in its configuration. The boot loader in turn loads up and executes the boot instructions of some application, usually an operating system, which performs its own startup and refreshing tasks. These tasks are under the control of, and follow the rules of, that operating system.

In summary, whatever is required to refresh a computer after turning it on is determined by its operating system.