Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!mit-eddie!mit-amt!mjkobb
From: mjkobb@mit-amt.MEDIA.MIT.EDU (Michael J Kobb)
Newsgroups: comp.sys.mac
Subject: Erasable optical drives
Summary: How the #$&#*# do they work?
Keywords: Erasable optical disk storage
Message-ID: <819@mit-amt.MEDIA.MIT.EDU>
Date: 11 Oct 89 21:20:18 GMT
Reply-To: mjkobb@media-lab.media.mit.edu (Michael J Kobb)
Distribution: usa
Organization: MIT Media Lab, Cambridge MA
Lines: 23


  Hello.  A friend of mine and I have been having a rather large argument
regarding how erasable optical (EO) drives work.  I maintain that the disk
is written to by heating the desired spot with the laser, then using the
magnetic head to set the field on that spot so that it's either a 1 or 0.  
Reading, I maintain, is done much the same way, by heating the desired spot,
and reading the field off of it with the magnetic head (both of these
presuppose that the magnetic characteristics of the medium are altered by the
heat, so that a relatively large head will really only act on the heated spot.
  My friend maintains that the drive is written to with the laser and the
magnet, but that it is read exclusively with the laser, depending on the
altered magnetic field of the molecules to either reflect or scatter the laser
beam.

  Question:  which, if either, of us is correct?  Could some kind soul point
me to a reference where I can get a complete description (MacWorld or MacUser
references would be preferred, since I have access to archives of them.  Or,
if someone would like to tell me where there's an online archive with this
info, and how I access it, that would be fine, too.)?

Thanks in advance.

--Mike