【Hitachi】 H-6585 Magnetic Disk Unit

The H-6585 magnetic disk unit was developed as a device with twice the capacity of the H-8598 (630MB/actuator). The basic system of this unit derived from the H-8576, but I/O control was done independently for each actuator mounted to the same spindle, and thus there was a problem in that, if one side performed a seek while the other side was performing a read/write operation, the reaction produced during the seek was transmitted via the base, causing a drop in the head positioning accuracy of the actuator.
To achieve a high TPI with this unit, a system was adopted in which an actuator was provided for each spindle, thereby avoiding mechanical interference between actuators. The number of disks per HDA was reduced compared to the single actuator system, and the rise in temperature of the HDA was alleviated. Therefore a completely sealed structure was used.
In order to achieve high-density recording, MnZn was used as the magnetic head material, and the 1-7 recording was used as the recording modulation system.
Each actuator had a capacity of 1,260MB, and was compatible with the IBM3380E.

H-6585 Magnetic Disk Unit Specifications
Completion date December 1985
Memory capacity per unit 5Gbyte/DKU
Memory capacity per spindle 1,260Mbyte
BPI 15,000BPI
Surface recording density 14Mbit/square inch
Disk size/quantity 14-inch/7 disks
Head type/number per actuator Lightweight MnZn ferrite/24+1(Servo)
Average access time 17ms
Disk rotation speed 3,600rpm
Data transfer speed 3Mbyte/s

H-6585 Magnetic Disk Unit