In May 1988, NEC announced the D5655 5-inch, high-capacity, high-speed hard disk unit for OEM.
This unit improved performance of the magnetic recording media, increased recording density by using 2-7RLL (Run Length Limited) code, which has a minimum magnetization reversal 1.5 times that of MFM (Modified Frequency Modulation), and achieved a memory capacity of 179.8MB, the highest in Japan for a 5.25-inch thin hard disk unit.
An average seek time of 18msec, the fastest in Japan, was achieved by, among other things, lightening the magnetic head movement mechanism and using a high-performance voice coil motor.
Noise during random seek was a low 45 decibels or less.
|Number of disks||4|
|Number of heads||7|
|Number of cylinders||1224|
|Memory capacity (unformatted) (MB)||179.8|
|Average seek time(msec)||18|
|Average rotational delay(msec)||8.4|
|Data transfer speed(kB/sec)||1250|
|Date first shipped||April 1988|