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NOTE:   This web site is not some kind of 'official' documentation hub for the XT-IDE card.
It is simply the result of someone who decided to add to the documentation that exists elsewhere.



XT-IDE  -  Wiping the MBR


You are at this web page either because you know what you are doing, or you have been directed here by someone who knows what they are doing.

MBR = Master Boot Record

In vintage PC's, the MBR is stored in the very first sector on a hard drive.  See here.

'Hard drive' includes, an IDE drive attached to the XT-IDE card, a CF attached to an XT-CF card, a CF in a {XT-IDE + CF-to-IDE adapter + CF} combination, etc.

This web page is about wiping the MBR, the first sector.  Of course, a technique or software that wipes the whole disk achieves the same result.

Following are six various options to wipe the MBR.  Take your pick.  Four are done on the vintage computer.  One is done within Windows 10/11 on a modern computer.  One is done within Linux on a modern computer.


 Option #1

On the vintage computer, you will use some of the functionality of the DOS program named TESTMBR.

Once TESTMBR has started:
1. Go into the advanced menu.
2. If you have multiple hard drives: If you need to target the second drive (BIOS drive 81h) instead of the first, use the 'Change target hard drive' option.
3. Use the option of 'Fill first sector with 00'.

Get TESTMBR from here.


 Option #2

On the vintage computer, execute the DOS program named WipeDisk, by Lo-tech.
In case it is relevant to you, note that WipeDisk wipes more than the MBR (the first sector) - it wipes the first 64 sectors.

Get it from here.

After you have executed WipeDisk, should you wish to verify that the MBR is 'wiped', see here.

IMPORTANT: Targets the first hard drive (BIOS drive 80h); relevant if there is more than one hard drive in your vintage computer.


Option #3

On the vintage computer, execute DEBUG.COM and then enter certain commands into DEBUG.

The commands are those shown in the 'Step 2 - Zero data in first sector' section of here.

After that is done, should you wish to verify that the MBR is 'wiped', see here.

IMPORTANT: Targets the first hard drive (BIOS drive 80h); relevant if there is more than one hard drive in your vintage computer.
To target the second drive (BIOS drive 81h) instead, substitute "81" in place of "80".


Option #4

Here, within Windows 10/11 on a modern computer, we will use HxD software ("Freeware Hex Editor and Disk Editor") to wipe the MBR on a CF.

It is critical that at step 7, that you select the right drive, otherwise you may render your modern computer unbootable.

1.   Install HxD software on your modern computer (obviously, if not already installed).
   
2.   Attach the CF to your computer via a suitable card reader.
   
3.   On the Windows desktop, right-click (repeat: right) on the HxD icon, then of the presented options, click on 'Run as administrator'.
   
4.   When the User Account Control window appears, click on [Yes].
   
5.   On the menu bar, click on [Tools] then [Open disk].   ( On early versions of HxD, [Extras] then [Open disk] )
   
6.   Untick the 'Open as Readonly' box.
   
  It is critical that in the next step, that you select the right drive, otherwise you may render your modern computer unbootable.
   
7.   Double-click on the drive that corresponds to the CF.   Guidance on this is shown at here.
   
8.   In the 'Warning' window that appears, click on [OK].
   
  Sector 0 and part of sector 1 is displayed, and the insertion point is at the first byte.
The MBR is sector 0 (512 bytes at offset 0 through 1FF).
We now want to fill all 512 bytes of the MBR (sector 0) with 00.
The following is one way of doing that.
   
9.   On the menu bar, click on [Edit] then [Select block].
   
10.   In the window that appears, set 'Start-offset' to 0, 'End-offet' to 1FF, then click on [OK].
   
  You will see that all 512 bytes of the MBR (sector 0) are selected.
   
11.   On the menu bar, click on [Edit] then [Fill selection].
   
12.   In the window that appears, click on [Zerobytes], then click on [OK].
   
  You will see that all 512 bytes are now 00.
   
13.   On the menu bar, click on [File] then [Save].
   
14.   In the 'Warning' window that appears, click on [Yes].
   
15.   Exit HxD.

Option #5

Here, we will use Linux on a modern computer to wipe the MBR on a CF.

See posts #3 and #5 at here.

 Option #6

FreeDOS has a 'CLEARMBR' option, which completely wipes the MBR.

So, on the vintage computer, boot from a FreeDOS boot diskette, then enter in the command:  fdisk /clearmbr

After you have done the above, should you wish to verify that the MBR is 'wiped', see here.

IMPORTANT: Targets the first hard drive (BIOS drive 80h); relevant if there is more than one hard drive in your vintage computer.