Barium ferrite perpendicular recording flexible disk drive

A 3.5" double-sided 4MB flexible disk and disk drive has been developed employing Toshiba\´s barium ferrite perpendicular recording medium and without using a track-following servo. High storage capacity, four times higher than that for a conventional 3.5" 1MB drive, has been obtained by increasing linear recording density to 35 kBPI by using pre-erase heads, together with high density recording techniques, such as head/media contact and azimuth alignment. Track density is 135 TPI, the same as that for a conventional unit, so that downward compatibility, capability of reading a 3.5" 1 MB flexible disk, is obtained. Good performace for the new flexible disk drive was assured by various tests, including overall evaluation tests through personal computers.