Booting from disks with partitions other than FAT 12

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Booting from disks with partitions other than FAT 12

Postby sanjeevmk » Thu Dec 08, 2011 4:17 pm

The tutorials here on bootloaders, use a FAT 12 formatted floppy drive. With some minor modifications, rather slashing of content, I wrote a bootloader that boots from a raw, unformatted disk. So , I bypassed all the FS related stuff that was shown here in the tutorials. It was similar to writing for a floppy but without any of the BPB,clusters etc hassles. Now, wanting to take the next step, I want to boot from a formatted disk.

Rather than FAT 12, I thought I would do it with a disk formatted with FAT 32. How should I go about it? Where can I find detailed and accurate documentation about the FAT 32 structure. The docs I found on the internet weren't so sure about what they were talking, and usually started with a warning that said, the information here might not be correct. Also, how would we go about booting from a disk formatted with any FS. It could be NTFS, ext 2/3/4 etc.? I know I will have to write appropriate drivers, but I could not find any official documentation explaining the complete structure of any of these file systems.

Sanjeev Mk
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Joined: Sat Nov 26, 2011 7:42 pm

Re: Booting from disks with partitions other than FAT 12

Postby Andyhhp » Mon Dec 12, 2011 10:05 am

The FAT12/16/32 spec is available as a .doc from the Microsoft Website, or look on

However, on a floppy disk, you really want to be using FAT12 as it has less filesystem overhead, meaning you can store more regular data on the data.

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