Learning from historical view of the progress in magnetic recording

One hundred years of magnetic recording from the invention of "Telegraphone" by V. Poulsen in 1898 is the history of continuous development that has migrated from wires to tapes to disks. From the historical view of the magnetic recording, it was deduced that an invention needs more than 20 years before its worldwide application and that major technological innovations take place with a periodicity of about 40 years. The latter period would be related to the generation change. The change from in-plane to perpendicular magnetic recording system seems very reasonable from the historical view. The technology should play a fundamental role in information storage systems in the first half of 21st century.