MBR Bootcode on FAT32 HDD

[ErikM]

Hi everybody,

at the moment I'm trying to analyse what exactly the formating of a partition in FAT32 does. I know, that has been done before, but I learn better by doing it on my own.

Know I realized that the Boot Code in the Volume Boot Record matches exactly to what I find in the Internet. But not the Code in the MBR.

What I did ist this:

-1- Write 0x00 to every sector using dd if=/dev/zero.
-2- create a primary partition.
-3- Format this partition with a Windows XP prof. SP2 OS to FAT32.

So this is a pure data storing HDD, no OS installed there.

Now my question :

where can I find the code explanation for an MBR with these specifications?

I looked at, for example, http://mirror.href.com/thestarman/asm/mbr/index.html
but they don't have the code i found...

I added a screenshot of "my" MBR.

Any ideas?

Thanks,

Erik

Attachments

MBR without OS / FAT32

[ErikM]

Sorry, wrong screenshot. This is the actual screenshot and this is the typical Win XP MBR. I'm sorry, my fault.

Can be closed... better deleted

Attachments

[beto]

well if u want to know on deep what its this code,one way u can use Debug a powerfull tool command acccesing by Int13h , to unassembly it and let u know what does it mean the opcode 33 C0 and so so : if im remeber that means disable ints.after that setting stack to segment 000 ,setting stack to pointer 7C00 to load on that memory zone the MBR , im not sure that first bytes are the called Bootstrap code, then at offset 1B0 its starting the Partition table info,but the best its "unassembly" from this way u can understand what its happening on deep well u need to know assembly Opcodes to do that aaah!.. a little tip when u find " CD 13 " that means Int13h

55AA its the boot signature...

Regards

[ErikM]

Hi beto,

thank you

Erik

[beto]

i got some free time & was reading my notes finally i find a usefull link, enjoy it http://www.ata-atapi.com/hiwmbr.html
by the way using debug u can got the MBR too or any sector ,

[ErikM]

Hi beto,

sry for the delay... thank you very much for your link

Erik

[beto]

u´r welcome

[Creator]

This is fully described it the Data Extractor documentation, I learnd if from there.