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Index > OS Construction > i need some help for writing a fat32 bootloader

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craciun



Joined: 11 Apr 2006
Posts: 7
craciun
hi, i've wrote a bootloader code for fat32 file system, and there is something strange in binary format after compiling.

this is code:
;<<<<<<<<<<start>>>>>>>>>>>>
jmp start_code
nop

oemname db 'MSWIN4.1'
bytespersector dw 512
sectorspercluster db 8
ressectors dw 38
numcopiesfat db 2
maxallocrootdir dw 0
maxsectors dw 0
mediadescriptor db 0f8h
sectorsperfat dw 0
sectorspertrack dw 63
heads dw 64
hiddensectors dd 63
bigsectors dd 3173121
bigsectperfat dd 3093
fatflags dw 0
version dw 0
firstclustofroot dd 2
fsinfosector dw 1
backupbootsect dw 6
reserved dd 0,0,0
driveid db 80h
rezervat_nt db 0
bootsignature db 029h
volumeid dd 56291043h
volumelabel db 'ChristmasOS'
filesystemtype db 'FAT32 '

start_code:
; here is the rest of code

I know that the first 3 bytes in a fat32 boot loader should be EB 5A 90
but i had seen on some partitions that byte 5A is 58. Wich is the correct one? I also want some code for reading and/or loading a file from a fat32 partition.
Post 18 Oct 2006, 17:59
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
use [code] tags around your code
Post 18 Oct 2006, 18:16
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Dex4u



Joined: 08 Feb 2005
Posts: 1601
Location: web
Dex4u
Just use
Code:
        jmp             start        nop    

You will find bootloader code for fat12, fat16, fat32 written ASM, C, brainf**k .
Also available in red, green, and blue.
Also nice load file from fat32 in asm you can copy, i mean look at.
http://home.no.net/tkos/info/fat.html

PS: Remember google is your friend.
Post 18 Oct 2006, 18:36
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