Booting is a process to bring the system up for working. This process checks the system components after power on and loads the operating system from the secondary storage device. This process involves many predefined tasks, which are carried out every time the system is switched on. Booting starts with the POST step followed by bootstrapping process.
The bootstrapping process begins with executing the software in ROM at a predefined address. This BIOS software contains a small functionality to search for devices eligible to participate in booting, and loads a small program from a boot sector. This small program, called as bootstrap loader or boot loader loads the operating system into memory and passes the control to it. This boot sector will be on any storage device.
This booting process takes a while depends on the machine configuration and the operating system. The total booting time is divided into three stages in cold booting (boot from shut down state) process.
· BIOS POST - the time for the power-on self test (POST)
· Pre-Logon - the time from BIOS POST handoff to the Windows Logon screen
· Post-Logon - the time from closing the Logon screen to a usable Start menu
These 3 time units make the total booting time. Users are always concerned about the booting time the system takes. All expect the system to be ready after it is switched on.
In fact we do not use the system’s full capacity and all its devices initially. Why to check the entire RAM in the beginning? Why to verify all the CPUs in the system initially? Why all network cards are to be verified?
The booting process should be such that the logon screen should be made available to the user as soon as he switches on the system. The limited set of hardware can be made available to the user initially. The booting process can be extended at the background to make the full system resources available to the user. Here the hardware and software resources are made available to the user as the user continues to use the system.
This lazy and demand based booting technique for quick system availability can be investigated for the next generation computer systems.
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