The single biggest factor driving this remarkable increase has been the ability to scale the technology. The ability to shrink both dimensions and tolerances while maintaining function defined progress for the first 35 years. Towards the end of this period there were transitions from linear to rotary actuation, from particulateto thin-film media, and from ferrite- to thin-film heads, but all without any change in essential function or mode of operation. However, one great difficulty was becoming apparent. Readback from inductive pickup scales poorly, and, despite great ingenuity