【Hitachi】 DK228A-65 2.5-inch Hard Disk Drive / DK239A-65 Hard Disk

The DK228A-65 was the first Hitachi drive to use GMR heads, which gave a recording capacity of 6.48 GB, about 1.3 times more than conventional MR-head drives. The disk speed was also boosted to 4,200 rpm from the 4,000 rpm of previous models. Together, the GMR head and faster disk speed enabled a maximum data transfer speed of 13.4 MB per second, which improved the drive’s overall processing speed. The drive had an ATA-4 interface, which was the industry standard at the time.

Specifications of the DK228A-65 hard disk drive
Introduced May 1998
Storage capacity per unit 6.48 GB
Recording density 250,000 bytes per inch
Track density 15,600 tracks per inch
Area recording density 3.9 Gbits per square inch
Number of disks 3
Number of heads 6
Average seek time Read: 12 ms
Disk speed 4,200 rpm
Data transfer speed 13.4 MB/s max.

As more hard disk drives were installed in notebook computers and other portable devices, vibration and shock resistance requirements became more stringent. Hitachi released the DK239A-65 in November 1998, which featured a magnetic-head load/unload mechanism, a first for Hitachi.
As more people began travelling with and using notebooks with built-in 2.5-inch hard disk drives on the road, notebooks and other portable devices had to be built with more robust shock resistance. To dramatically improve the hard disk drive’s non-operation shock resistance, Hitachi made use of a load/unload mechanism that removed the magnetic head from the disk when not reading or writing. Furthermore, to raise the drive’s storage capacity to 6.49 GB, Hitachi incorporated a number of leading technologies at the time, such as MEEPRML signal processing and on-the-fly ECC correction.

Specifications of the DK239A-65 hard disk drive
Introduced November 1998
Memory capacity per unit 6.49GB
Recording density 315,300 bytes per inch
Track density 19,500 tracks per inch
Area recording density 6.15 Gbits per square inch
Number of disks 2
Number of heads 4
Average seek time Read: 12 ms
Disk speed 4,200rpm
Data transfer speed 16.3 MB/s max.