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How to patch FAT32 boot sector

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#26 dencorso



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Posted 01 August 2009 - 04:15 AM

I cross-posted it on original thread:

Thanks, jaclaz! I have updated the KillCHS program to v. 1.2, by incorporating Icecube's suggestions (thanks, Icecube!), and revising a little more the whole code. The new version is now in place of the former, still in post #22, so that your posted link remains valid. You both rock! :idea:
Side note: The source code remains not consistently formatted, but is nevetheless, a little better, visually.

#27 online


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Posted 06 August 2009 - 10:38 AM

Not sure if the patching at every boot-up could be useful in your case... :idea:
Please, see here

#28 calfared

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Posted 18 July 2011 - 06:10 PM

For what it's worth, here I offer the boot-land community my revised version of Clemens Fruhwirth's KillCHS utility, both compiled and as source code, alongside with Fruhwirth's original code renamed killchs.ori, to help those interested in determining what I added to the code. My revised version can patch the NTFS boot loader and both flavors of the FAT-32 NTLDR boot loader (viz. MSWIN4.1 and MSDOS5.0). It has been compiled with djgpp's gcc 4.10 and runs in the NT-family Windows OSes, in Win 9x/ME and in plain DOS (but CWSDPMI is required).
Usage is simple:
KillCHS <filename.ext>
It will crash, however, if run without providing a filename.
Update (Aug 01, 2009): I've incorporated Icecube's suggestions (in post #24, below) and revised further the code. The new version (1.2) is more user-friendly, and only accepts one parameter, but it'll just complain and do nothing in case none or more are provided in the command line, instead of crashing on none and ignoring all parameters but the first, when more than one is provided.
Attached File(s)
KillCHS.7z (34.59K)
Number of downloads: 250

Forgive my ignorance, but how you use it? I'm having problem of "missing NTLDR" and informed me that it could solve.


Edited by calfared, 18 July 2011 - 06:12 PM.

#29 Wonko the Sane

Wonko the Sane

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Posted 18 July 2011 - 07:45 PM

Forgive my ignorance, but how you use it? I'm having problem of "missing NTLDR" and informed me that it could solve.


calfared, it doesn't work like this :cheers:.

I told you here:
that that was a possible cause.

The general idea is that ONCE we know (because you are so kind as to post the required info):
  • the EXACT error
  • the EXACT configuration you have
  • the EXACT hardware you have
the issue can be solved by this or by ANOTHER fix, since the CAUSE is another one.
In any case, as told you, it is possible that some fixes are needed in the partition table of the MBR, anyway.
(or it is possible that the cause is a completely different thing, so that it needs a completely different fix).

Right now we are still in the "I'm ill Doctor, Help!" stage, reference:

Start a new thread.
  • Describe EXACTLY what you did.
  • Describe EXACTLY the behaviour you are getting.
  • Describe EXACTLY what you are trying to achieve.
  • Describe EXACTLY the hardware you are using.

This way someone will be able to actually help you solve your problem, as opposed to make guesses (educated :cheers:, but still guesses) about what your problem may be and what solution you may find for it.

Anyway the little program is made to patch a bootsector, that you need to extract from the actual Volume, and after the patch, re-write to the proper location (first sector of volume).
You can do the patch manually, with a normal hex/disk editor (such as Tiny Hexer) following the info given in the referenced "original" thread here:


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