what is this Operating Systems bs

like when i first learnt about computers and OSes in depth i had this question why OS like why can’t we give cpu instructions directly as 0s and 1s in a program doesnt seem so hard why install this 10GB OPerating system thingy just so that i could write a file this is what led me here to discuss the OS

so first of all what exactly is the need for an OS so we humans somehow managed to turn rock into circuits that can add numbers and follow instructions if the instructions where given in 0s and 1s and thats what we call computer

computers at the beginning was hardwared to ask for instructions to be entred Operating Systems changed this it gave us a place to store all programs operate multiple programs at once and also abstracted away the complexity of everything

how does an OS work

OS is just what we call the entire thing as a whole OS is made out of serveral programs at its heart is a program called the kernel but before we dive in lets see what happens when your computer boots

BOOT PROCESS

• first thing that happens is your cpu turns on and enters rest mode or smthn and then it starts executing code at address 0XFFFFF or smthn not sure but anyways it executes the code and it is mapped to a chip at the mother board wher a software called BIOS or UEFI exists (this is firmware)

BIOS is seen in older computers and is simpler to learn and UEFI is seen in newer ones BIOS (Basic Input Output System) and UEFI (unified existansible firmware interface)

once BIOS/UEFI starts executing it starts

POST

(power on self test) basically it turns on each component like ram , cpu gpu and stuff and check if its working if its not working it will display an error and stops the boot process

finding boot partition

in BIOS systems the first part of the disk is mapped to boot related things and in UEFI theres this boot partition nvmeP1/boot and thats where your bootloader lives

bootloader

whats a bootloader its the program that will boot your OS like it will set it up and turn on the kernel and stuff

it does stuff like show you the grub menu , and stuff grub btw is grand bootloader smthn so ya it does all that and once kernel starts executing bootloader will stop its execution now everything is left to the main guy the kernel

kernel

Kernel is the heart and soul of the operating system its like a platform where other apps are run linux kernel is so OP,like hell

this is like a platform for every other program to run it made computer programs more accessible kernel is the only program that runs in CPU in ring 0 (aka kernel mode)

when you boot your computer , first thing that bootloader does is load the kernel into ram and start kernel , kernel has full control over the cpu every other program runs on top of the kernel ie kernel calls them.

Kernels are optimized beasts they have everything from process management to file system management and the devs who make it are soo OVerpowerdly intelligent that their brains might be larger than our planet metaphorically

kernel provides these APIs to interact with it and utilize its features so

example

we are tasked to make an app called vidcall which allows peeps to video call others but we can either make it as a pure binary from scrathc designed to run without an OS or as an app designed to run in linux

1. without OS implementation

you’ll have to write how the computer interacts with hardware componenets , logic for how your app will talk to the display the user is using how it will talk to its camera what voltage to send what pixels to write up , how each font is rendered , how the gui will be renderd how your computer interacts with the disk to write data into it how should output be formated and everything and user will not be confident to run this thing as it might corrupt his data even with all this work

this is like a simple app will take GBs of code or even more its madness we have to implement all the things ourselves

2. with kernel things are a lot easier things just work you could just use c programs open files close them open a window you can use gtk toolkits to render window faster

kernel handles talking of different hardware no need to worry about disk drivers etc

drivers

drivers are programs that are designed to talk to kernel and hardware they be like midddleman between hardware and kernel and kernel talks to the app

so kernel does all the heavy lifting also it manages security and prevents apps from overwiting one another mad respect to those kernel devs out there but drivers are important as kernel doesnt know how to talk to hardware directly its the drivers that tell to do so

like for any hardware let it be you gpu , to operate it one must know which and which ports and circuits to send signals to make the chip perform this and this task so there is a gpu driver is like the logic for that as a program

Nvidia doesnt like competition and didnt opensource the driver for their gpu so like they could gate keep their secrets , such evil that aside there are like huge manuals on how to talk to machine out there so like driver devs has a good grip on c and learning those things i believe

kernels are not same

different kernels are different like windows kernel is not same as linux kernel and so on theyll have different APIs theyll have different filesystems theyll have different set of drivers

since drivers talk to hardware and kernel no windows driver wont work for linux so that is that

same reason why windows app wont run on linux and vice versa cause kernel APIs are differnt

kernels mount filesystems

filesystems are like entire datastructures to store stuff in disk in a meaningfull way and apis to retrieve and open the data stored in a way that makes sense for humans we came up with file names to assign to a specific address in the disk so much is handled by there kernel here

filesystems are of difffernt tyeps and some of them have encryption compression some of them dont some of them work on everything some of them dont and so on

• Btrfs is the linux cuttting edge one
• ext4 is linux default works fine
• NTFS is windows’s one

and stuff like FAT32 and fat64 etc are used in pendrives boot partition etc linux kernel can identify partition formats and switch to that compatabilty so damm smart

there is so much stuff to learn its so vast isnt it so lets skip past a lot of things and just say we have kernel started the first program that kernel starts is the initSystem process id one this is responsible for starting other processes and background tasks aka (daemons)

now most peeps use systemd cause it manages stuff like login logout , user entry journal and network and much more systemd is not the only one tho some people like void linux users have their own i forgor its name which is lighter init system will also start the shell

and if you are on arch linux like me youll be greeeted with a tty tty is a program that just does the bare minimum we can see the shell and interact with it what is a shell you ask its another program duhh

shell

a shell is a program that accepts human readabilsh syntax parses them and tells the kernel so its like a middleman between kernel and you

altho its human readable only technical people use it , your granny prolly wont be using the shell unless she is Ex compsci major or smthn anyways shell has commands like

atoms> mkdir hello

the arrow you see there is the prompt , thats why we call stuff command prompt its a stuff you configure in your shell

mkdir is a c program compiled to binary that talks to kernel api and asks it to create a directory there so you can see its like a way to launch programs to itneract with kernel also you could do some shell scripting and adding logic etc

I personally use ZSh or nushell but most famous shell is defo bash shell files are made executable .sh

font rendering

in a tty you can see fonts , there are bitmaps of each letter stored in kernel that is used to display fonts in a tty bitmaps are pixelated grid of what all to light up they donts scale well

kernel handles all the driver talk and using the display to display them woahh

you could use your computer just fine from the shell and tty but most modern peeps we need a GUI

GUI Graphical User Interface

a GUI is basically OP , it allows us to visually see stuff all the windows the buttons all is GUI so GUI is implemented by a program that talks to kernel to make and render this and such

they call stuff called screen buffers and the kernel will draw them with help of display driver

what is responsible for this a display server it handles the drawing of rectangles and buffers on screen

a window manager is another program that manages stuff like position of windows and stuff so it tells the display server what to draw and where

the gui for apps like the buttons and evrything you see inside the app is rendered by itself like it can be opengl or using stuff like gtk or an electron app with chromes renderer so ig that makes enough sense and this whatever being rendeerd gets passed window manager does the management of position of windows and additonal styling like canvas drawin blur etc and finally passes the output to display server which will draw the thing it also handles keybord related stuff

and fonts are loaded from ttf files its like vector fonts basically maths and there are libraries for text shaping rendering etc and while using a terminal inside a gui environment tedxt is rendered like this with math

KDE and GNOME

these are desktop environments and what they are is a suite of (background working programs daemons) a window manager and other programs like taskbar notification bar quick settings and all those things

sounds fckin cool right how clueless we normies are when it comes to whats going on in computers

so whats our plan we are going to make a fuckin OS by ourselves cause whatever these peeps are gate keeping we will sieze it like they gate keep stuff from us sayin shit is soo hard we cant dooo it but actually shit is easy they just make it sound hard so they can have coolness all to themselves

_<

altho like what we are gonna make is a toy OS and wont even be near the fraction of what a real OS is we will learn something from it

next part defo ill showcase my toy bootloader or OS lol just for the fun of it (ps the image is not my rice i stole the image for it from google )