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The drive letter if F, and i want to read its boot record for this task : http://joelgompert.com/OS/lesson1.htm ... [ i am using xp ] I cant get the l command to work properly... when they ask us to type this is debug.exe : 

-l 0 0 0 1

I replaced it with :

-l 0 5 0 1

Cause i do not have a floppy at drive A... I get a prompt telling me :

C:\WINDOWS\system32\cmd.exe - debug.exe An application has attempted to directly access the hard disk, which cannot be supported. This may cause the application to function incorrectly. Choose 'Close' to terminate the application. And the option to choose are Close and Ignore. I selected ignore and it gives me the following output in the CMD :

Disk error reading drive F

What am i doing wrong ? Isn't it supported to use a flash drive ? Any alternative programs for the task ? Any help will be appreciated :)

Rohan Bojja
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1 Answers1

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In all NT-based systems (Windows NT, 2000, XP/2003, Vista/2008, 7/2008 R2) direct disk access to hard drives is prohibited for older software. There are special APIs for accessing hard drivers directly, but older software simply does not know them.

DEBUG under XP does allow for direct access to floppy disks, so if you want to learn DEBUG, an USB floppy drive is an option. If you want to learn about data structures on HDD and don't care about debug, look for more recent disk editor. I think you'll find something suitable in this article at Wikipedia.

MBu
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  • Is it possible that any disk editor is similar to DEBUG and has similar features... ? – Rohan Bojja Jan 28 '12 at 17:12
  • What do you mean when you write "similiar"? For real DEBUG was a debugger for DOS programs, it was included in XP for compatibility I suppose. Today Microsoft's debugger is called WinDBG, you can download it for free from http://msdn.microsoft.com/en-us/windows/hardware/gg463009.aspx. If you want to use it for disassembly of MBR code, take a look at http://blogs.msdn.com/b/ntdebugging/archive/2008/03/06/disassemble-the-mbr.aspx – MBu Jan 28 '12 at 17:52
  • Another idea: use one of recent disk editors to load MBR and save it as a normal file, then use DEBUG to load that file and continue with the task. – MBu Jan 28 '12 at 18:15
  • Yet another idea: use virtual floppy drive (http://vfd.sourceforge.net/), load an image of bootable floppy disk, see if DEBUG sees it. – MBu Jan 28 '12 at 22:54