【Hitachi】 H-6587 Magnetic Disk Unit

The H-6587 disk unit was developed as the successor of the H-6586 disk, and inherited its basic system. It had a capacity of 2.92GB, which was the highest in the world at the time. The disk rotation speed was increased from its long-time value of 3,600rpm to 4,260rpm, and the transfer speed increased accordingly to 4.2Mbyte/s, opening the way to high-speed processing.
This unit had a capacity of 2.92GB from the beginning, and thus at the announcement of the IBM3390-3 which went on sale later, compatibility was maintained for PCM use by restricting the capacity by about 3%. Therefore, the compatibility follow-up period was just a few months.
In this way, international attention was drawn to Hitachi's PCM business, and the company showcased its advanced technology.
With this welcome from the market, Hitachi established a new plant in Orleans, France to strength production and achieve worldwide expansion.
For the coated disks used in this unit, this was the final generation of products, and later products adopted sputtered disks, which are more suitable for high-density recording.

H-6587 Magnetic Disk Unit Specifications
Completion date October 1990
Memory capacity per unit 22.7Gbyte/DKU
Memory capacity per spindle 2.92Gbyte
Surface recording density 55Mbit/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 4,260rpm
Data transfer speed 4.2Mbyte/s

H-6587 Magnetic Disk Unit