Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uflorida!gatech!fabscal!dorn
From: dorn@fabscal.UUCP (Alan Dorn Hetzel)
Newsgroups: comp.arch
Subject: optical disk in NeXT
Keywords: optical disk NeXT
Message-ID: <520@fabscal.UUCP>
Date: 15 Oct 88 03:02:06 GMT
Organization: Fabscal Systems, Inc.., Atlanta, GA 30308
Lines: 14

The optical disk in the NeXT system  is actually a "magneto-optical"
disk.  A laser is used to lower the magnetic coercivity of a very small
area of the disk, which can then be written by a very weak (and therefore
small) magnetic field.  The change in magnetic alignment affects the
optical properties of the surface, which allows the stored data to be
read using a lower power laser.

That's the gist of it anyway.  Since it spins at RPM's similar to a real
hard disk, and since it uses reasonable head transport technology, it can
be about the same speed as one (though writing is a little slower, reading
should be just as fast)

Dorn
gatech.edu!fabscal!dorn