1985	HP 97501
	1st commercially significant usage of carbon over-coated sputtered recording layer media in a disk drive

Why it’s important The superior consistency, higher quality and long life of sputtered metals recording layers with protective carbon overcoating caused rapid replacement of the prior plated metal and oxide recording layer media. Today all HDD media used this technology.

Discussion

Production shipment of HP 97501 in March 1985 according to Disk/Trend.
Internal media shipment date currently unknown but likely to be earlier than commercial media supplier's shipments to HDD manufacturers.

Other early drive shipments by Vertex, Maxtor and SyQuest.

Additional information

Early shipments of such media by commercial media vendors to drive companies include:

June 1984 by Trimedia
July 1984 by Komag
LinData several months after Trimedia
Source: Oral History Panel on Hard Disk Drive Transition to Thin Film Media, Computer History Museum, April 17, 2006

Early disclosure of the use of carbon overcoating "to permit recording measurements by actual flying of a Winchester-type head for periods of hours" disclosed by W. T. Maloney, Sperry research, “RF-SPUTTERED CHROMIUM-COBALT FILMS FOR HIGH-DENSITY LONGITUDINAL MAGNETIC RECORDING,” IEEE TRANSACTIONS ON MAGNETICS, VOL. MAG-15, NO. 6, NOVEMBER 1979