【Hitachi】 DK516 Magnetic Disk Unit

This unit was marketed as a high-capacity OEM disk unit employing a 5.25-inch disk.
The combination of a sputter disk and a thin-film head was used for high-density recording, thereby realizing a comparatively large head float distance.
In terms of electronics, higher speed and performance were achieved in control microprocessing by equipping the unit with two CPUs.
These technologies dramatically improved equipment reliability, and earned the unit a reputation as a high-reliability, high-performance, large-capacity disk—characteristics previously thought to be difficult to simultaneously achieve.
However, in terms of the trend of the era, all manufacturers of server systems were moving toward the more compact 3.5-inch HDD, and this unit marked the end of the 5.25-inch HDD.

DK516 Magnetic Disk Unit Specifications
Completion date 1990
Memory capacity per spindle 1.65Gbyte
Surface recording density 95Mbit/square inch
Disk size/quantity 5.25-inch
Head type/number per actuator Lightweight thin-film head
Average access time 13.5ms
Disk rotation speed 3,600rpm
Data transfer speed 3Mbyte/s

DK516 Magnetic Disk Unit