Hi 👋 just wanted to let you know that your content is very special. Tech Content Creators focus a lot on Hacking and Defense but Malware Analysis and Reverse Engineering need a little bit of attention so thanks !
Thanks! I don't think I'll do something like this very soon. This videos are sort of a by-product of me learning something. And its gonna be quite a long time until I learn how to make a simple OS.
@@DanielMiulet-jo9ko Well, the first public version of Linux was less than 10k lines of code; of course, that didn't include even a file system :) And quite a few of those lines were just the definitions and boilerplate. One of the tricky things with following Linux development is that whole GNU (and friends) thing. The kernel is just the kernel, after all. DOS allowed you to run programs and navigate files; back in the day, that was enough to count as a simple OS (heck, microcomputer Basic was really an OS :D ). But I expect people aren't going to be satisfied with anything that doesn't have at least memory protection, asynchronous I/O and pre-emptive multi-tasking nowadays :D
I like to switch from the 16 bit Real Address Mode with 64 kb segment size for all segment register, into the 16 bit "Big" Real Mode with a segment size of 64 kb for CS and SS segment, but for DS, ES, FS and GS segment size of 4 gb with A20 address line on. This Mode is compatible to the 16 bit BIOS function of the mainboard and graphic BIOS and additional alows to write/draw into the linear framebuffer (located in the 4th gb) of VBE 2 or VBE 3 videomodes for high resolutions. Example 1920x1200x32 with 16: 10 aspect ratio for 28" LCD monitor using Radion 9750 PCIe with intel Core2quad CPU 2700mhz.
x86 assembly is easy to learn. I began on C64 with 8 bit CPU only 3 register, no FPU, no mul and no div instructlons, but most routines need 16 bit calculation. x86 is much easier to use. Documentation: Intel developer manual for 16 bit and from AMD in pdf files.
@@maxmuster7003 thank you , friend , i started learning it that day and yes it's easy for making simple stuff(also super fun), but I wonder if making complex stuff with it will require a in-depth knowledge of the x86 architecture
Not only is It faster it's also a smaller instruction for x86 if I'm not mistaken. Don't quote me on that though because it's been a long minute since I've done some assembly prog.
xor ax, ax would do the same as mov ax, 0, but with additional capability of setting the flag to zero and clearing carry according to the logic of xor. And xor consumes less clocks than mov does in some old architectures.
We can write our string directly into the screen memory without using a bios function. vga text screen default 80x25 with 16 colors and 8x16 character size and 8 text pages mov ax, 0b800h mov es, ax mov di, Location cld mov si, OFFSET string ; ds:si mov ah, color mov cl, len L1: lodsb stosw dec cl jnz L1 .... string DB "Hello World" len = ($ - string) Location = (Y * 160) + (X * 2)
Theory : Power Supply gives power to all devices and does POST test Then Bios is loaded into Memory from disk Bios then finds Bootloader to execute it, It sees Boot sequence in Bios setting to find Boot device Then inside Boot device first 512 bytes are reserved for Bootloader called Master Boot record or Boot sector Then it loads Bootloader into memory and executes it
cli and sti are needed if we want to change an interrupt vector address offset/segment in memory like the timer interrupt 8 at the address 0:0020 = 4 bytes. If we don’t stop the timer interrupt and we try to override the old vector the interrupt can occur between changing the offset and changing the segment address and accidently jumping to a wrong address with no valid interrupt service routine(ISR). We have to prevent this.
Very good video but one question - if the program overwrites what is in the bootloader then how does the system boot after the program has finished executing ?
The program would overwrite what's in RAM, not what's on the hard drive. When you reboot, the whole thing gets loaded from hard drive again. However, there's no modification of the program in RAM here either. The program and the bootloader are the same - or rather, the sample program here is just made to run when the computer starts (and tries to boot from the drive). It doesn't actually do any "bootloading", it just prints a message and stops the CPU (without any way of waking it up again, so your only option is a reboot). The demonstration is just an almost-minimal setup on running code when booting from a hard drive. That's it. It just prints a message to make it obvious that it actually works. The whole mechanism is the same as in the very first IBM PC (hooray for compatibility; UEFI is a completely new and incompatible system, but old-school BIOS boot is still there), which is also why it's all so tiny and simple - the computer reads a single 512 byte block of data from the boot drive, loads it into _physical_ memory at address 0x7c00, checks that it has the "signature" (AA55) at the end, and points the CPU's instruction pointer to 0x7c00. That's it. No file systems, no processes, just a 512 B slab of code and data you can work with to actually proceed with the boot (or in this case, print a message and stop). This is _not_ a bootloader - not yet. It's just a tutorial on how to run a basic program from a bootsector on computer startup. But hey, it's "part 1" for a reason - we have to start somewhere :) An actual bootloader would prepare a few things, load the actual program/system (presumably from the same drive, which is why you get the drive number as one of the "inputs" here) and run it. There's a limit to what you can do with ~510 bytes of code and data :D
No, I just like it because it has all you need to start. I'm sure there is plenty more resources, blogs, books but I didn't check yet. There are also udemy courses, but they are paid of course
Microcontrollers are usually programmed through flashing/burning. E.g. the Arduino Uno has an ATMega 328 microcontroller with integrated memory (both persistent and temporary). You put the program into that memory, and that's it. In contrast, the IBM PC was designed with extensibility in mind, so there's a "protocol" of how everything gets initialized, because it needs to work with a wide variety of software and hardware - that was the whole point of the PC (though of course IBM expected that the actual PC would only be made by them; instead, competitors quickly sprung up with compatible PCs and the rest is history :)). There's a little dance when the computer starts to make sure those basics are satisfied - the BIOS discovers memory, a boot disk, loads the boot sector from that disk to memory and sets the CPU to execute from there. That's what Part 1 here is all about - getting the BIOS to execute _our_ code from the boot drive. Of course, you _can_ have bootloaders with Arduino - but the bootloader is just flashed like any other program. The main point here is to make it faster to test new stuff - instead of having to flash the Arduino every time you need to test a change, the bootloader will e.g. load the program over a serial link. Arduino boards have a built-in bootloader that does just that. You usually don't deal with things like "loading programs from a hard drive" or "understanding a filesystem" in a microcontroller; though it's certainly possible, of course, the main draw of microcontrollers is that they're really simple and small. Of course, there are tons of notable "embedded" systems that work pretty much the same way as a PC, like your router or that Windows Embedded kiosk. That has little to do with practical programming of Arduinos, though :P
Pretty useless and full of inaccuracies. To begin with, the first thing is not just two bits, but a transition instruction (JMP 003E or JMP 7C3E), because each boot sector has a table that you completely lack. For disks it is one type, for floppies another. I know from experience that what works on a virtual bow tie does not always work on a real one. I've tried making my own OS, not to replace one, but just out of curiosity if someone with poor assembly knowledge like me could make a working, albeit rudimentary, OS. In the end, I never finished it. It was in my native language, not English. Here it is from the link below. czcams.com/video/y3e8ImJUoiE/video.html
Part 2:
czcams.com/video/BQGbBCqUGCc/video.html
Hi 👋 just wanted to let you know that your content is very special. Tech Content Creators focus a lot on Hacking and Defense but Malware Analysis and Reverse Engineering need a little bit of attention so thanks !
please increase font size next time
Pollo campero tambien?
I need a microscope on Android tablet.😂
font size is fine
@@MurderByProxy no campestre mejor
Please watch this on a normal screen.
The POST is performed by the BIOS/UEFI. Good job. Keep going.
Damn bro this is gold hidden beneath shit i am glad i could discover this
I love this! can we have a full series where you build a simple OS?
Thanks! I don't think I'll do something like this very soon. This videos are sort of a by-product of me learning something. And its gonna be quite a long time until I learn how to make a simple OS.
What would count as "simple OS"? :)
@@LuaanTilinux from scratch would be a “simple os”. If you really want it… from scratch, you can write your own programs and your own kernel
@@DanielMiulet-jo9ko Well, the first public version of Linux was less than 10k lines of code; of course, that didn't include even a file system :) And quite a few of those lines were just the definitions and boilerplate.
One of the tricky things with following Linux development is that whole GNU (and friends) thing. The kernel is just the kernel, after all.
DOS allowed you to run programs and navigate files; back in the day, that was enough to count as a simple OS (heck, microcomputer Basic was really an OS :D ). But I expect people aren't going to be satisfied with anything that doesn't have at least memory protection, asynchronous I/O and pre-emptive multi-tasking nowadays :D
@@screeck I am also trying to learn how to make a simple OS , would love to get some tips and resources from you
I like to switch from the 16 bit Real Address Mode with 64 kb segment size for all segment register, into the 16 bit "Big" Real Mode with a segment size of 64 kb for CS and SS segment, but for DS, ES, FS and GS segment size of 4 gb with A20 address line on. This Mode is compatible to the 16 bit BIOS function of the mainboard and graphic BIOS and additional alows to write/draw into the linear framebuffer (located in the 4th gb) of VBE 2 or VBE 3 videomodes for high resolutions. Example 1920x1200x32 with 16: 10 aspect ratio for 28" LCD monitor using Radion 9750 PCIe with intel Core2quad CPU 2700mhz.
your content is awesome , been wanting to learn assembly for a while and you've just gave me the motive to do so
x86 assembly is easy to learn. I began on C64 with 8 bit CPU only 3 register, no FPU, no mul and no div instructlons, but most routines need 16 bit calculation. x86 is much easier to use. Documentation: Intel developer manual for 16 bit and from AMD in pdf files.
@@maxmuster7003 thank you , friend , i started learning it that day and yes it's easy for making simple stuff(also super fun), but I wonder if making complex stuff with it will require a in-depth knowledge of the x86 architecture
Bruh, mov ax, 0x00?
xor ax, ax
Faster to manipulate CPU registers than load from RAM. And yes, that instruction clears the ax register.
Thanks, will use that next time
Not only is It faster it's also a smaller instruction for x86 if I'm not mistaken. Don't quote me on that though because it's been a long minute since I've done some assembly prog.
xor ax, ax would do the same as mov ax, 0, but with additional capability of setting the flag to zero and clearing carry according to the logic of xor. And xor consumes less clocks than mov does in some old architectures.
A very good video. Great content and easy to understand. Thank you!
nice, waiting for next episode. Please post video for ARM64 also
Can't wait for the next episode!
Well, this video is in a format "this video is for beginner"
The amount of knowledge required to event understand the video is massive.
We can write our string directly into the screen memory without using a bios function.
vga text screen default 80x25 with 16 colors and 8x16 character size and 8 text pages
mov ax, 0b800h
mov es, ax
mov di, Location
cld
mov si, OFFSET string ; ds:si
mov ah, color
mov cl, len
L1:
lodsb
stosw
dec cl
jnz L1
....
string DB "Hello World"
len = ($ - string)
Location = (Y * 160) + (X * 2)
awesome, keep going 🎉
Theory :
Power Supply gives power to all devices and does POST test
Then Bios is loaded into Memory from disk
Bios then finds Bootloader to execute it,
It sees Boot sequence in Bios setting to find Boot device
Then inside Boot device first 512 bytes are reserved for Bootloader called Master Boot record or Boot sector
Then it loads Bootloader into memory and executes it
cli and sti are needed if we want to change an interrupt vector address offset/segment in memory like the timer interrupt 8 at the address 0:0020 = 4 bytes. If we don’t stop the timer interrupt and we try to override the old vector the interrupt can occur between changing the offset and changing the segment address and accidently jumping to a wrong address with no valid interrupt service routine(ISR). We have to prevent this.
insta like for the posters, going to watch the video now :)
Thanks haha
you can also code in C and let the compiler create the assembly for you.
einfach gut gemacht !!!
I made some open source projects for DosBox using batch files and x86 assembly. Have fun.😊
thank you, so 510-0 times is 510 and two addresses are 2*8bits? is 512 as MBR? ;) I'm just beginner in ASM. You're my first teacher :)
amazing, I'm very interested in ur content
could you make the font size in your terminal/code editor a bit bigger because it is very difficult to see especially on mobile
Thanks for feedback, I'll make it bigger in the next video.
please zoom in on the text editor
You know you can zoom in on the text editor yourself, right? Have you tried it?
@CristiNeagu true but I don't think you can do that on desktop
Great video! Thanks
this was really cool
please don't stop 3 video's in
I like your accent cos i can understand everything ❤
Would be nice to be able to figure out how to flash a bootloader to xbox series to boot on brand new SSD
You could technically write a bootloader in JavaScript like a personal version of virtual box?
It worked well.
wow MASM havnt see that for 30 years
It's NASM.
Very good video but one question - if the program overwrites what is in the bootloader then how does the system boot after the program has finished executing ?
The program would overwrite what's in RAM, not what's on the hard drive. When you reboot, the whole thing gets loaded from hard drive again.
However, there's no modification of the program in RAM here either. The program and the bootloader are the same - or rather, the sample program here is just made to run when the computer starts (and tries to boot from the drive). It doesn't actually do any "bootloading", it just prints a message and stops the CPU (without any way of waking it up again, so your only option is a reboot).
The demonstration is just an almost-minimal setup on running code when booting from a hard drive. That's it. It just prints a message to make it obvious that it actually works. The whole mechanism is the same as in the very first IBM PC (hooray for compatibility; UEFI is a completely new and incompatible system, but old-school BIOS boot is still there), which is also why it's all so tiny and simple - the computer reads a single 512 byte block of data from the boot drive, loads it into _physical_ memory at address 0x7c00, checks that it has the "signature" (AA55) at the end, and points the CPU's instruction pointer to 0x7c00. That's it. No file systems, no processes, just a 512 B slab of code and data you can work with to actually proceed with the boot (or in this case, print a message and stop).
This is _not_ a bootloader - not yet. It's just a tutorial on how to run a basic program from a bootsector on computer startup. But hey, it's "part 1" for a reason - we have to start somewhere :) An actual bootloader would prepare a few things, load the actual program/system (presumably from the same drive, which is why you get the drive number as one of the "inputs" here) and run it. There's a limit to what you can do with ~510 bytes of code and data :D
@@LuaanTi Thanks for the response. I will watch the remaining two videos before I ask any more questions !
do u have a github for that sir?
Writing bootloader in VS Code (technically in a browser)... that's what we achieved so far 😕
Editors and IDEs have always been "bloated". Back in the 80s, programmers joked that EMACS actually meant "Eight Megabytes And Constantly Swapping"...
Nice 👍
3 seconds into the video... hm he will use a VM indeed😂
Why MBR mode and not UEFI?
is osdev your only resource for learning this?
No, I just like it because it has all you need to start. I'm sure there is plenty more resources, blogs, books but I didn't check yet. There are also udemy courses, but they are paid of course
@@screeck can you recommend some?
I've heard that this book is very good: "Operating Systems: Three Easy Pieces"
There is also www.viralpatel[.]net They have some OS related tutorials
@@screeck tnx man
Intel developer manual for 80286 CPU
Hello my friend, make more vídeos please
Interested in fixing booting?
No boot flag, and no MBR or sectors.
All drives & comm. dev. boot.
Set or search file: boot.lst
Screw this, write a bootloader for SPARC!
hi, nice video. but could you tell me how do you make your vm look so smooth?
I gave it 8GB ram and max video memory.
@@screeck i give mine 16 process, 256mb videomemory and 16gb ram and it lags so bad
@@Apathyy322 I think it depends more on how strong your CPU is
make a video where you write a bootloader for arduino 😆
Where is the last Jedi poster?
I don't like sequels :/
ACPI
Can u also tell for Embedded system? like Arduino , ESP......
Microcontrollers are usually programmed through flashing/burning. E.g. the Arduino Uno has an ATMega 328 microcontroller with integrated memory (both persistent and temporary). You put the program into that memory, and that's it.
In contrast, the IBM PC was designed with extensibility in mind, so there's a "protocol" of how everything gets initialized, because it needs to work with a wide variety of software and hardware - that was the whole point of the PC (though of course IBM expected that the actual PC would only be made by them; instead, competitors quickly sprung up with compatible PCs and the rest is history :)). There's a little dance when the computer starts to make sure those basics are satisfied - the BIOS discovers memory, a boot disk, loads the boot sector from that disk to memory and sets the CPU to execute from there. That's what Part 1 here is all about - getting the BIOS to execute _our_ code from the boot drive.
Of course, you _can_ have bootloaders with Arduino - but the bootloader is just flashed like any other program. The main point here is to make it faster to test new stuff - instead of having to flash the Arduino every time you need to test a change, the bootloader will e.g. load the program over a serial link. Arduino boards have a built-in bootloader that does just that. You usually don't deal with things like "loading programs from a hard drive" or "understanding a filesystem" in a microcontroller; though it's certainly possible, of course, the main draw of microcontrollers is that they're really simple and small.
Of course, there are tons of notable "embedded" systems that work pretty much the same way as a PC, like your router or that Windows Embedded kiosk. That has little to do with practical programming of Arduinos, though :P
I like your accent
I just got booting from hard disk
Not in this manner; *No*
Now, just do the tests on real hardware. FD/HDD/USB 🤭
bootable CD-ROM el torito format floppy emulation on Drive: A
@@maxmuster7003 Yes, booting PC from CDROM is probably the best solution these days.
siema
siema
wave more w/ you hands 0:32 off
Pretty useless and full of inaccuracies. To begin with, the first thing is not just two bits, but a transition instruction (JMP 003E or JMP 7C3E), because each boot sector has a table that you completely lack. For disks it is one type, for floppies another. I know from experience that what works on a virtual bow tie does not always work on a real one. I've tried making my own OS, not to replace one, but just out of curiosity if someone with poor assembly knowledge like me could make a working, albeit rudimentary, OS. In the end, I never finished it. It was in my native language, not English. Here it is from the link below.
czcams.com/video/y3e8ImJUoiE/video.html
I could be your dad, WTF?
😂
Do you realize that your posters are backwards?
Laugh, I'm joking.
You almost made me check it lol
Don't leave the series in the middle
u deserve millions of subs for this , i wanna be your friend may I ask if you have discord?
Thanks bro