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Index > OS Construction > Switch to Protected Then Load Kernel from floppy.

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calpol2004



Joined: 16 Dec 2004
Posts: 110
calpol2004
does anyone have any example bootloaders that enter protected mode then load the kernel from a floppy with a FAT12 file-system. i've been trying with an example which i have attached (just to give you an idea to what im looking for) but the syntax is too distant from FASM for me (just got hang of porting from MASM), but im making a complete mess of it. i have looked also at the BOS boot sector although everything is in 16bit which will make switching to pmode in the bootsector a general pain...unless of course i do it later in the kernel but i may as well get it over and done with in the bootloader. and once i've gone into to protected mode i don't really want to switching back into to real mode all the time as your code just ends up looking like mud. if any of you have got any examples which do as i've descibed could you attach them? or maybe you've got a link to a website which may give me more information, would you mind posting that?

im currently waiting for all my books on OS dev from amazon but they are taking ages Evil or Very Mad! i've got some book on concepts which basically teaches me loads of theory and some useful algorithms .etc but not much actual code Confused. and another book on MSDOS to which has an extensive library of interrupts many of which are BIOS. however until the rest come i've got very little reference on how to implement a bootloader Mad. i could use bootprog but i may as well make a MS-DOS application and autoexec batch it at startup as its practically the same thing Sad, and considering i want to create a OS not a Sub-OS this would not suit my needs (that means you Dex4u, if you suggest bootprog one more time in this forum i will scream Shocked )


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Last edited by calpol2004 on 11 Mar 2006, 16:50; edited 2 times in total
Post 11 Mar 2006, 16:42
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Borsuc



Joined: 29 Dec 2005
Posts: 2466
Location: Bucharest, Romania
Borsuc
Have you tried Bona Fide. They got some nice tutorials Wink
Post 11 Mar 2006, 16:47
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calpol2004



Joined: 16 Dec 2004
Posts: 110
calpol2004
funnily enough thats where i got the example i attached from. i've looked around there site a bit, but they only go as far as teaching you how to write text in a bootloader Sad.
Post 11 Mar 2006, 16:49
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Dex4u



Joined: 08 Feb 2005
Posts: 1601
Location: web
Dex4u
calpol2004 wrote:
i could use bootprog but i may as well make a MS-DOS application and autoexec batch it at startup as its practically the same thing Sad, and considering i want to create a OS not a Sub-OS this would not suit my needs (that means you Dex4u, if you suggest bootprog one more time in this forum i will scream Shocked )
@calpol2004, No i do not think your ready for "bootprog" just yet, maybe you should try his other bootloader, you can get it here: http://alexfru.chat.ru/epm.html#los4d

Also you need to do some reading on how OS like linux boot Rolling Eyes
http://www.control-escape.com/linux/bootload.html
Post 11 Mar 2006, 18:21
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Octavio



Joined: 21 Jun 2003
Posts: 366
Location: Spain
Octavio
calpol2004 wrote:
does anyone have any example bootloaders that enter protected mode then load the kernel from a floppy with a FAT12 file-system.

perhaps it exists, but is very dificult to put all this on just 512 bytes, the usual solution is to use a second stage loader (like GRUB), but for a asm programmer it should be easy to load the kernel in real mode ,and allow the kernel to switch to protected mode, most assemblers will let you to mix 16bit realmode with 32bit pm code and most asm OS work like this.
If you are a C programmer better use something like GRUB.
Post 12 Mar 2006, 12:02
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