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I was just wondering if anyone could help me out I wanted to create my own simple OS just as a hobbyist project and a learning experience. But I was wondering a few things I know I need to create the boot sector in asm but I want to makeeverything else in C++. So i was wondering if anyone knew how I could execute a .com file I make with c++ with my asm program that is in the boot sector. And after I create the boot sector where should I go from there thanx for any help
Kas2002
use C. see http://www.linux.org Thats all the os you need... :D
You might look into Linux. It's open source, so you can see how they've done it. Also, some of the disk utility companies like Power Quest have some info about how disks boot.
It's not impossible for one person to write a simple OS. I know someone who wrote one for a mini-computer long before PCs, and of course Linus Torvalds did it!
However, it IS IMPOSSIBLE for one person to write a good-modern GUI OS! Microsoft has something like 1000 programmers working for 3 years on each new version of Windows. It would take one programmer 3000 years! No one person has the knowledge or the time to accomplish a task like this. Then, you get the driver problem... Drivers are now written by the hardware manufacturers. They typically don't share the details you would need to write your own driver.
You should find more than enough info here: http://flashdaddee.com/forums/forumd...?s=&forumid=20
Also, check out osdev.org
yeah ive heard windows 2000 was written in 5 million lines or
something??! :eek:
Yes, but do remember that Linus Torvalds created linux by himself to lern the inner workings of minix. Of course this was far from the grandeur of todays linux, and it had many bugs and was pretty worthless, but it was a beginning.Quote:
Originally posted by DougDbug
You might look into Linux. It's open source, so you can see how they've done it. Also, some of the disk utility companies like Power Quest have some info about how disks boot.
It's not impossible for one person to write a simple OS. I know someone who wrote one for a mini-computer long before PCs, and of course Linus Torvalds did it!
However, it IS IMPOSSIBLE for one person to write a good-modern GUI OS! Microsoft has something like 1000 programmers working for 3 years on each new version of Windows. It would take one programmer 3000 years! No one person has the knowledge or the time to accomplish a task like this. Then, you get the driver problem... Drivers are now written by the hardware manufacturers. They typically don't share the details you would need to write your own driver.
I can sympathize with your attempt to develop your own OS as a hobby and to learn the inner workings of your PC. My best advice would to grab a LFS (Linux from scratch) distro and start from there. As you'll be FORCED to edit and recompile the kernel several times, you'll no doubt become familiar with it.
Go check it out here .
You may even want to consider working with some embedded systems. You can gain a grasp on doing some very low level programming without all the hassel that an operation system entails.
You could also consider to take a look at Minix. A small open source OS. Minix was developed to teach students how an OS works.
http://www.cs.vu.nl/~ast/minix.html
Supprised? I'm not....Quote:
Originally posted by pode
yeah ive heard windows 2000 was written in 5 million lines or
something??! :eek:
Go look at the source code to my s00per l337 Operating System ;)
http://www.SteveOS.tk
If you take senior to grad level OS courses you will have to a least a simple one. I did!!!
Interesting! I thought that it was a rather unusual exercise!Quote:
If you take senior to grad level OS courses you will have to a least a simple one.
I had to write and OS called KASH and another one in grad school.
What was the other one?
there was a link posted with the exact amount somewhere on here, think it was more like 2 million.Quote:
Originally posted by pode
yeah ive heard windows 2000 was written in 5 million lines or
something??! :eek:
i dont really remember the exact but it could be 2 million.
ok
I had to do that at school last year.
First a little knowledge about the boot sequence on a PC:
On power up the BIOS looks for the first executable bootable device (floppy bootsector for example) and loads its contents into memory at the address 0:7C00 (512 bytes will be put out there) and then simply 'jumps' the processor to 0:7C00 and executes that code.
then, your code (at 0:7c00) is supposed to look for the rest of the code because 512 bytes is not enough for a whole OS :P
this part is in general called stage1.
that's where it starts getting interesting. the purpose of stage1 is to find stage2 on the floppy disk, load it in memory and then jump to it!
stage2 is a little bigger that stage1 and it purpose is to load the kernel somewhere in memory (before the 1MB mark obviously), disable interrupts, enable the A20 gate (= access to the rest of the memory), setup the GDT and IDT registry which is used by the protected mode and then jump into protected mode.
Then stage2 must move the kernel at the 1MB memory mark (just above the I/O area) an jump to it.
The kernel can be written in flat C++, but you'll have to write printf yourself and access the video card yourself. Also, you might need to program the keyboard and make a fgets() function.
because there will be no libraries available for you.
still intersted in writing an OS ?
Just for the record, I am not a newbie in assembly, neither in C, and neither in compiling and linking, and it still took me a whole month (fulltime) to debug that and make it work. The only reason why I did that is because we needed it at school to run some tests. Otherwise there is no way I would have done that.
if you're still interested, drop me a line at [email protected] and I'll email you some of the code and interesting links
i cannot imagine anything more exciting than what you described above (not that I dont understanf /have not heard it before)Quote:
Originally posted by xmdvp
ok
I had to do that at school last year.
First a little knowledge about the boot sequence on a PC:
On power up the BIOS looks for the first executable bootable device (floppy bootsector for example) and loads its contents into memory at the address 0:7C00 (512 bytes will be put out there) and then simply 'jumps' the processor to 0:7C00 and executes that code.
then, your code (at 0:7c00) is supposed to look for the rest of the code because 512 bytes is not enough for a whole OS :P
this part is in general called stage1.
that's where it starts getting interesting. the purpose of stage1 is to find stage2 on the floppy disk, load it in memory and then jump to it!
stage2 is a little bigger that stage1 and it purpose is to load the kernel somewhere in memory (before the 1MB mark obviously), disable interrupts, enable the A20 gate (= access to the rest of the memory), setup the GDT and IDT registry which is used by the protected mode and then jump into protected mode.
Then stage2 must move the kernel at the 1MB memory mark (just above the I/O area) an jump to it.
The kernel can be written in flat C++, but you'll have to write printf yourself and access the video card yourself. Also, you might need to program the keyboard and make a fgets() function.
because there will be no libraries available for you.
still intersted in writing an OS ?
Really, or are u being sarcastic?
I love itQuote:
Originally posted by xmdvp
still intersted in writing an OS ?
it always makes me smile when I read this. People love doing things when the dirty job's been done before, or when they don't know what they are talking about.Quote:
Originally posted by Travis Dane
I love it
someone said: there's 10 kinds of people: those who understand binary and those who don't ;)
xmdvp
I've read through your post and what i made up of it is thatQuote:
Originally posted by xmdvp
or when they don't know what they are talking about.
writing your own OS takers time and has to be done on a low
level meaning you have to do everything yourself (like printf),
And that's what i love.
I agree that I had fun writing my own printf() and getc() function.