Re: Interesting One

[John Dow <jmd () nelefa org>]

On Tue, 2002-10-29 at 18:15, John Orr wrote:
>   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".  

Apologies if I'm talking out of my nether regions, but (looking at it
superficicially) I wouldn't have thought that storing/reading a magnetic
impulse would be quite as clear cut as zeroes and ones. I'd have thought
that some fuzzy interpretation was required ie, x to y is the normal
range taken to represent a zero, a to b to represent a one. In this
case, it's entirely possible that, for a known drive with known
parameters, it *may* be possible to say "yes, that's a one but it's
slightly higher than normal so it may have been a one previously as
well".

This is, of course, nothing more than utter speculation from someone who
knows nothing about it ;-)

J


-- 
John Dow <jmd () nelefa org>
http://www.nelefa.org
33 Shines