【Hitachi】 H-8566 Magnetic Drum Unit

This magnetic drum employed a floating head and had the highest performance among Japanese-made units at the time. It was commercialized in 1968 as a magnetic drum unit for the HITAC-8000 Series.

After developing a fixed head type magnetic drum in 1959, Hitachi had increased capacity, but by using the new floating head system, they were able to narrow the spacing between the magnetic head and the media on the surface of the rotor to 5μm (1/6 of the previous value) -thereby attaining a capacity of 2MB (megabytes), 6 times the previous capacity. A dual-body planar slider with stable floating characteristics was used for the new floating head, and mounting density was increased by using a 4-multi-track structure. This magnetic drum memory unit was configured to enable connection of up to a maximum of four 2MB magnetic drums to a single unit.

The features of this magnetic drum included an extremely short access time (10.3ms for the main unit) and extremely stable performance with few errors. It was used mainly for large high-speed electronic computers, but as capacity increased, it came into wide use in new fields.

This magnetic drum was a product which utilized the results of joint research by Nippon Telegraph and Telephone Public Corporation and Hitachi, Ltd.

H-8566 Magnetic Drum Unit Specifications
Unit model name H-8566
Completion date 1968
Head type Floating head
Head floating distance 5 μm
Memory capacity 2 MB
Recording system TM recording system
Average access time 10.3ms
Data transfer speed 1.4Mbit/s
Drum Name of unit used ---
Number of tracks 512
Rotation speed 3,000 rpm
Rotor dimensions 360 ø×470 mm
Recording density 25 bit/mm
Connected systems Digital switching systems
Seat reservation systems
HITAC-8000 Series

H-8566 Magnetic Drum Unit, AppearanceH-8566 Magnetic Drum Unit, Internal Mechanism