The first full-height 5.25 inch hard disk drive
for personal computers
, introduced in 1980 by Shugart Technology (now Seagate Technology
). The ST-506 stored up to 5 megabtyes
using MFM encoding
. It transferred data at 625 kilobytes per second
The ST-506 (like the ST-412
) was interfaced to a computer via a disk controller
. The interface was a faster version of the Shugart Associates SA1000
interface, which was in turn based upon the floppy disk drive
interface. Two cables connected the controller to the disk. The 34-pin control cable controlled mechanical motion and data was read or written serially using two pins of the 20-pin data cable.
Other companies copied the interface, creating a universal de facto standard
that was further strengthened by its revision to support Seagate's 10 MB ST-412 drive that was adopted for the IBM PC XT
Around 1990, SCSI
superseded ST-506. These eliminated the problems of matching controllers to drives by physically integrating a controller with the drive, allowing interleave ratios
and other disk parameters to be optimised by the manufacturer rather than the system integrator.
Connector pin-out (http://www.gamesx.com/hwb/co_ST506.html).