【Hitachi】 H-8567 Magnetic Drum Unit

This magnetic drum was commercialized in 1970 as a magnetic drum unit for the HITAC-8000 Series. This was done by reducing size and increasing capacity of the previously commercialized H-8566 magnetic drum with floating head system.

Volume was reduced to about 1/4 the previous volume by, for example, reducing diameter of the rotor from the previous 360mm to 250mm, and adopting a built-in drive motor. An increase in capacity to 4MB (megabytes)-twice the previous capacity-was achieved by, among other things, reducing spacing between the floating magnetic head and media on the rotor surface, and using the FM recording system. Average access time was 10.3ms, as before.

The magnetic drum used in the H-8567 magnetic drum unit was commercialized as a standalone drum with the model name FV-2450, and was also marketed for use in digital switching systems and by other companies in the same industry. The FV-2540 magnetic drum was a product developed through joint research by Nippon Telegraph and Telephone Public Corporation and Hitachi, Ltd.

H-8567 Magnetic Drum Unit Specifications
Unit model name H-8567-1/-2
Completion date 1970
Head type Floating head
Head floating distance 1.7 μm
Memory capacity 4 MB
Recording system FM recording system
Average access time 10.3 ms
Data transfer speed -1 type:2.2 Mbit/s(serial transfer)
-2 type:8.8 Mbit/s(4 bit parallel transfer)
Drum Name of unit used FV-2540
Number of tracks 856
Rotation speed 3,000 rpm
Rotor dimensions 250 ø×420 mm
Recording density 56 bit/mm
Connected systems Digital switching systems/DIPS/
Subscriber data communication systems
Seat reservation systems
HITAC-8000 Series

H-8567 Magnetic drum unit, AppearanceH-8567 Magnetic drum unit, Internal Mechanism