John, Think atomically. There can be millions of atoms in a apace the size of a pin tip. A write head need not turn every atom in a layer of magnetic material one way or the other. It only needs to turn just enough 'clearly' one way in order for the read head to pick it up again. If we talk about a layer of magnetic material that is just .0001" thick we are still talking about layers upon layers upon layers (need I go on....) of atomic material.
It can be done! Dan Darden. =========================================== Email [EMAIL PROTECTED] for your security questions and information. Hoax Info: http://hoaxbusters.ciac.org =========================================== "Everyday I beat my own personal record for number of consecutive days I've stayed alive" -- Author Unknown =========================================== -----Original Message----- From: John Orr [mailto:JOrr@;austinbank.com] Sent: Tuesday, October 29, 2002 12:15 PM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: Interesting One Personally, I think he is full of... hot air. Bits are either "on" or "off", "1" or "0". If you change that pattern (i.e. write over the same data area with a different sequence of bits), then the previous state of that field would not be determinable. Granted, there may be some residual magnetic field left on a particular area that is now "0" that had been "1", but the converse would not be true. There would be no residual field to read on an area that is now "1" that had been "0". Sounds like sales fluff to me. Anyway, that is my opinion, based on years of experience and a good knowledge of physics. -John -------------------------------------- John Orr VP/CIO Austin Bank 903.759.3828 x2113 903.297.3094 fax [EMAIL PROTECTED] >>> "Dave Adams" <[EMAIL PROTECTED]> 10/28/02 04:06PM >>> Greetings Folks, I had an interesting conversation today with someone from FAST (Federation Against Software Theft) They pretend not to be a snitch wing of the BSA. Anyway, to get to the point, the guy that came to see me said that their forensics guys could read data off a hard drive that had been written over up to thirty times. I find this very hard to believe and told him I thought he was mistaken but the guy was adamant that it could be done. My question is, does anyone have any views on this, or, can anyone point me to a source of information where I can get the facts on exactly how much data can be retrieved off a hard drive and under what conditions etc etc. Thanks Dave Adams This message (and any associated files) is intended only for the use of the individual or entity to which it is addressed and may contain information that is confidential, subject to copyright or constitutes a trade secret. If you are not the intended recipient you are hereby notified that any dissemination, copying or distribution of this message, or files associated with this message, is strictly prohibited. If you have received this message in error, please notify us immediately by replying to the message and deleting it from your computer. Messages sent to and from John Crowley (Maidstone) Ltd may be monitored. Internet communications cannot be guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. Therefore, we do not accept responsibility for any errors or omissions that are present in this message, or any attachment, that have arisen as a result of e-mail transmission. If verification is required, please request a hard-copy version. Any views or opinions presented are solely those of the author and do not necessarily represent those of John Crowley (Maidstone) Ltd.