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iisbob
05-13-2002, 09:20 PM
Recently, while reminicing with a collegue about the " good ol' 16 bit DOS " days, we got on the subject of various commands and their ( dis-)continued use.

Among one of these o so useful but forgotten commands was Debug.exe-used to use it a lot when programming, among other various tools.

He adroitly reminded me of just how useful it still is when he told me of his difficulty lately in removing a very stubborn Linux partition. Seems that all the third party tools he'd been using just seem to incomplet4ly do the job-or just caused some various sorts of problems.

Even Ranish (http://www.ranish.com/part) seemed to not be able to help; neither Partiton Magic nor good old FDISK seemed to do him any good either.

He said that being almost at his wits end he recalled using Debug.exe to wipe a drive many years ago, and rooted around until he found his old paperwork on the proper usage of it; then proceeded to use it-worked like a charm!

He says it wiped that drive like a blizzard in June! http://www.PCGuide.com/ubb/tongue.gif

This of course awoke my old DOS memories, including that o so obscure tool usage, so i dug up a copy of one of my old boot disks, and proceeded to experiment with it's parameters until i could nail down just how it used to work; the following is the syntax needed in order to do a COMPLETE wipe of your hard drive regardless of the type of file system/partition you use.

WARNING! This will wipe the drive completely!!

>debug { enter }
{ type only the cmds in bold and hit enter after each }

xxxxxx F 200 L1000 0
xxxxxx A CS:100
xxxxxx MOV AX, 301
xxxxxx MOV BX, 200
xxxxxx MOV CX, 1
xxxxxx MOV DX, 80 { use 80 for primary drive, 81 for a secondary drive }

xxxxxx INT 13
xxxxxx INT 20
xxxxxx { leave this line blank and hit enter }
>G [ then hit enter, this will execute the script }

Next just reboot and run FDISK/FORMAT as you normally would to create a parttion & file system.

This completely destoys the master boot record sector and allows you to reinstall any you choose.

for some good links on how Debug works you can try PCGuide (http://www.pcguide.com) and also Computer hope (http://www.computerhope.com)

Enjoy! http://www.PCGuide.com/ubb/biggrin.gif

PS

If you need to ge the Debug file, it can found on most 95/98 CD's-or you can go here, { Tech_95 debug.exe (http://www.techadvice.com/W95/S/start-up_disk_w95.htm)



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iisbob

Hike naked!-it gives color to your cheeks!!

sea69
05-13-2002, 11:40 PM
way cool iisbob!

I remember the first time I used a debug (not that long ago compared to you!)


had your friend tried delpart?


really good one to copy and save this. [insert thumbs up here]^[/thumbs up]

machine language isn't it?

http://www.PCGuide.com/ubb/wink.gif


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sea1_69@hotmail.com

homepage (http://www.seanweb1.homestead.com/index.html)
http://www.PCGuide.com/ubb/tongue.gif

[This message has been edited by sea69 (edited 05-13-2002).]

pentachris
05-14-2002, 02:21 PM
Very cool, iisbob! That's gonna be copied and pasted into a text file on a boot disk for sure! http://www.PCGuide.com/ubb/biggrin.gif

One question: does it wipe the drive (write zeros), convince the mbr to forget about the partitions it had assigned space for, or maybe both?

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Some mistakes are too much fun to make only once.

Reid
05-14-2002, 08:46 PM
The script clears the partition sector: http://www.firmware.com/support/bios/hdclear.htm

iisbob
05-14-2002, 09:35 PM
I think Ried's link says it better than i can! http://www.PCGuide.com/ubb/biggrin.gif


And yes, this is a very good example of what programming nightmares used to be made of!! http://www.PCGuide.com/ubb/eek.gif


{ this is why i chose to concentrate on hardware! http://www.PCGuide.com/ubb/tongue.gif }

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iisbob

Hike naked!-it gives color to your cheeks!!

borgdrone1of2
05-14-2002, 11:24 PM
hello thx for the hard drive wipeing info

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resistance is invigorateing lol

UPENDRA UPADHYAY
05-16-2002, 09:10 AM
can this compeletly wipe the hard drive? can any data recovery software recover the data from wiped hard drive? I heard about some software which is used by incomtax department to recover data from formatted drive by this software can it be recovered?

pentachris
05-16-2002, 11:25 AM
No, it won't clean your drive. Like Reid said, it only clears the partition sector - the very first sector on the hard drive where the partition information (also called the Master Boot Record or MBR) is stored.

To clean a section of the drive you can use Ranish Partition Manager (http://www.ranish.com/part/). Arrow down to the area you want to clean and press "E" for "Erase." You'll have to confirm this choice. The chosen area will be filled with zeros.

I think that there are methods (maybe not software but equipment) that can recover some data even after that, but not with a huge success rate - maybe only 50%-75% of the data. I think it has to do with residual magnetism and being able to see that even though this part of the drive says "00000000" right now, it said "01101011" for so long that it's still detectable.

Or something.

http://www.PCGuide.com/ubb/biggrin.gif

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Some mistakes are too much fun to make only once.

iisbob
05-16-2002, 07:25 PM
If you read my original post i did state that this will destroy the current master boot record, and i also stated it will clear { wipe } your drive. I should've been a little more clear on that part; as stated above it doesn't really wipe your drive sector by sector ( like zeroing ) , but it destroys the pointers to the sectors, basicly giving your drive the appearance of never having been partitioned/formatted. The data is still there, just that there is no addressing info for a normal utility to recover it.

If you want a true wipe, with %99 no possible data recovery, then use BCwipe ( http://www.freewarenet.com/downloads/genutils/bcwipe.html), it's uses the US goverment standards for a complete drive wipe ( 7x default overwrite with random characters ) and you can specify the no# of wipes. This is the link for the older free version, i believe the newer one is shareware.



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iisbob

Hike naked!-it gives color to your cheeks!!

sea69
05-16-2002, 08:06 PM
cool site iisbob- does BC wipe work ok for winXP?

http://www.PCGuide.com/ubb/wink.gif



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sea1_69@hotmail.com

homepage (http://www.seanweb1.homestead.com/index.html)