os

• An Operating system (OS) is a basic software that makes the computer to work.
• When a computer is switched on, there is no information in its RAM.
• At the same time, in ROM, the pre-written program called POST (Power on Self Test) will be executed first.
• This program checks if the devices like RAM, keyboard, etc., are connected properly and ready to operate.
• If these devices are ready, then the BIOS (Basic Input Output System) gets executed.
• This process is called Booting.
• Thereafter, a program called “Bootstrap Loader” transfers OS from hard disk into main memory.
• Now the OS gets loaded (Windows/Linux, etc.,) and will get executed.

Booting process is of two types.

• Cold Booting
• Warm Booting

Cold Booting:

• When the system starts from initial state i.e. it is switched on, we call it cold booting or Hard Booting.
• When the user presses the Power button, the instructions are read from the ROM to initiate the booting process.

Warm Booting:

• When the system restarts or when Reset button is pressed, we call it Warm Booting or Soft Booting.
• The system does not start from initial state and so all diagnostic tests need not be carried out in this case.
• There are chances of data loss and system damage as the data might not have been stored properly.