The H-6586 magnetic disk unit was developed as a device with 1.5 times the capacity of the H-6585 (1,260MB/sp).
For this unit, Hitachi decided to exploit its own in-house disk manufacturing capability, and eliminate the previous 14-inch disk, develop a new 9.5-inch disk, and use a thin-film head for the first time. An access mechanism, which was high-speed and high-precision at the time, was achieved by using a linear mechanism with a ceramic rail for the actuator, and developing a voice coil motor with a powerful neodymium magnet.
The volume of the HDA was successfully reduced by a significant margin with high-density mounting design around the HDA, and twice the capacity per unit was achieved by installing 8 HDA's in the same area as the IBM3380K.
In a thin-film head, the magnetic circuit and coil pattern are formed on a wafer using semiconductor technology, rather than forming the head with conventional machining and winding, and the result is improved performance due to the finer magnetic circuit parts. Achieving this required investment in new, previously unused equipment such as sputtering equipment and pattern forming equipment.
The formed patterns were fine, and defects could result even from tiny amounts of dust, and thus these pieces of equipment were all installed in clean rooms, and this also increased overall equipment investment.The capacity per actuator was 1.89Gbyte. They were compatible with the IBM3380K, and were sold as PCM disks.
The units completed with the support of these technologies could store twice as much data in the same floor area as an IBM machine. They were very popular internationally, and acted as the detonator of growth for Hitachi's PCM disk unit business.
|Completion date||July 1988|
|Memory capacity per unit||15Gbyte/DKU|
|Memory capacity per spindle||1.89Gbyte|
|Surface recording density||35Mbit/square inch|
|Disk size/quantity||9.5-inch/9 disks|
|Head type/number per actuator||Lightweight thin-film head/30+1(servo)|
|Average access time||12.5ms|
|Disk rotation speed||3,600rpm|
|Data transfer speed||3Mbyte/s|