Well, physics didn't change, but our understanding of it did. Modern read heads are based on the giant magnetoresistive effect which was only discovered in 1988

Well, physics didn't change, but our understanding of it did. Modern read heads are based on the giant magnetoresistive effect which was only discovered in 1988. It's actually one of the fastest transitions from fundamental physics discovery to wide use (GMR read heads were widely used from 2001-2002 or so)