Working with computers — What happens when a computer is switched on?

What happens when a laptop, mobile phone or tablet wakes up after being shut down for a while ?

Linux bootloader screen. Attribution: Reseletti, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

If you have used a computer which has Linux or one of its distributions (like Fedora) operating system, you might have seen a series of lines scrolling in front of you, this is the POST(Power On Self Test) then you can view a screen which displays the motherboard temperature along with CPU voltage and other system vitals, as soon as the computer is switched on. These are the steps followed by the motherboard firmware being employed, in order to execute the bootloader program.

Two types of motherboard firmwares are :-

• BIOS (Basic Input Output System)
• UEFI(Unified Extensible Firmware Interface)

AMIBIOS (American Megatrends) mounted on the motherboard. Attribution: © Raimond Spekking, via Wikimedia Commons

This small non-volatile chip mounted on the motherboard, contains the primary software program. This program helps the bootloader to boot the required systems. Subsequently, the Operating System is loaded and the screen containing the Window, Icons, Menu and Pointer is visible to us.

Now onwards, everything is controlled by the operating system which acts as a mediator between the software and hardware of a computer. However, kernel is the paramount program of an OS. It controls all the connected devices and exists in the memory even after the device is switched off.

Some renowned operating systems (OS) of today are :-

• Windows
• Linux
• Mac OS
• iOS
• Android

The tasks performed by an OS include :-

• Memory Management — Allocating and deallocating memory in RAM (Random Access Memory)
• File management — Ensuring sufficient memory is available to load files from disk to the memory and vice versa.
• Input/Output processes — Handling requests from hardware and loading appropriate device drivers.
• Process management — Dividing the program into multiple running instances and managing them.
• Resource allocation — Combining process management with memory management to achieve optimum efficiency.
• Interpretation — Understanding user commands like screen touch, key press, mouse hover, etc.

The way computers work is far more ingenious than meets the eye. It certainly cannot be contained within a few articles. The developments we see today will be followed by many more in the future for computers stem from the amalgamation of maths, science, curiosity and imagination. And as long as our imagination isn’t shackled by anything, the opportunities to progress are limitless!