#OSdev 01 Coding your own MS-DOS operating system in C

Join dr. JB for the ultimate operating system coding adventure: building Doctor DOS (D-DOS), a fully functional MS-DOS clone from scratch in C!

We lay the foundation for a 3-tier system:

❤ OS API/middleware: Links the shell to the kernel through "system calls"
♣ Kernel: Win/Mac/Linux during DEV; The main D-DOS x86 kernel during PROD

In Ep01, we code store() (write 1 byte to screen/file) and load() (read 1 byte from keyboard/file) "system calls", plus internal utility functions—no standard C library, just pure low-level programming. Expect live coding, bugs, and fixes, like my days teaching network engineering and coding.

What You’ll Learn:

🎓 Designing a 3-tier OS architecture
🎓 Coding custom system calls (store, load)

🔔 Subscribe for Ep03 of my AES-NI backdoor series or perhaps Ep02 of the Memory Allocator (coming soon).! Like, comment with your fave retro OS, and join the dr. JB crew!

#OperatingSystem #LowLevelProgramming #OSDev #CProgramming #MSDOSClone #CodingTutorial #CommandProcessor #TechEducation

Note: I had to compress the audio of the first 20% of the video (to minimize the file size, but also the length). The audio quality is still good though, it might just feel a little awkward not recognizing my voice. But I'm "myself" 30min into the video. :) And I have hand-made the subtitles of that first sequence. Enjoy!

- Table of Contents -
🍒 = You get the cherry (code works!)

00:00:00 Project Overview & Visuals
00:35:56 Organizing the project
01:02:07 store(): Writing to files/screen
01:19:05 Troubleshooting sub-Makefiles
01:47:22 First 🍒
01:51:53 load(): Reading from files/keyboard
02:19:59 Second 🍒
02:27:50 Testing our API

[garakchy]

I know dr Birch from the very beginning. Now seeing him address thousands of viewers, if not millions, makes me proud. I knew that he would become famous for being god of C.

[karlo_siric]

What is this? Like best content on youtube for CS, C and low level for sure, don't ever stop doing these things Dr. Jonas please, this is simply nothing short of amazing work! :)

[CodeLangtonsEntropy]

I just finished watching Sir, this is very interesting, i will rewatch while coding to get a better understanding as this is very new concept to me, super enjoyable to watch sir, thank you, very excited for part two :)

[thehagenbret]

I think it's a great fundamental project. Looking forward to all of your videos to come.

I'm a self learner in CS for the last 8 years. It's difficult to find content as valuable as yours.

I recommend giving any extra reading material on specific sections you find useful.

[mohamemdtalbi]

Dr Jonas = Doctor c and Computer Science one of the best programmer in C

[redred-bp]

thanks man !! your videos are amazing You definitely have the best YouTube channel that covers low-level programming

[codekundan]

Thanks Dr Jonas Birch. Your content is goldmine for low-level programming.

[guillermogaleanofernandez]

I wish I had a class like this in college!
Excellent content! 👏👏👏👏👏

My favorite retro OS is IBM OS/370 MVS 3.8j (for mainframes).
Greetings from Paraguay!

[Quanta-]

doc u are a genius i swear❤ hehe 1 min of video uploaded i commented

[Solving_Engineer]

Awsome project Doc. This looks like a little bit advanced level . But looks cool. Really waiting for part2. So, Part 2 when?

[maxmuster]

Before the user can do an input the system have to check and configure the hardware components, the memory, the video and the sound for example. A lot of the hardware is configured from the mainboard bios and Windows/Linux use bios functions to get the amount of memory. There are memory locations that are reserved from the bios and other location are free to use for the OS.

[aleksandr]

cool "robovoice", I like it)

[vamestm]

I have never written a line of C in my life, can i learn C by just coding alongside this video? extremely motivated!

[Davtd.]

arent the typecasts at some points unnecessary?

[kowalski]

Question: how different is this from a NT OS (like windows 3.1) ?

[zadahmed]

can you recommend good resources to learn C?

[MosabeJaouchi-ilmn]

Dr. Jonas, I have a question. I see that you have a great collection of videos in which you build projects from scratch. My question is how do you build these complex projects and explain them in two to six hours of videos, I'm a beginner and I think I don't know many of your topics.

[adityagaur]

What are the pre requisites for this doc

[abdosayed]

I know nothing about OS dev, but Would that have desktop and icons abd gui like windows? Even a much simpler one?

[maxmuster]

Is it importend to have a special sequence to include the library in C?