The ST-412 interface and its variants were the de facto industry standard for personal computer hard disks until the advent and wider adoption of the IDE or ATA interface in the early 1990s. The ST-506 and ST-412 (sometimes written ST506 and ST412) were early hard disk drives introduced by Seagate in 1980 and 1981 respectively, that later became construed as hard disk drive interfaces: the ST-506 disk interface and the ST-412 disk interface. It quickly became a de facto interface standard in the industry, although it was never formalized, or even given a formal. It used a ST-412 MFM (Modified Frequency Modulation) controller which unfortunately went to the great bit bucket some time ago. Porter the (total) worldwide shipment of all 5. Provide a contamination free environment. Electronics are packaged on two printed circuit boards. Read/write. The controller must change the state of the Reduced Write Current signal to the ST-506 (on pin 2 of the control cable) depending on the cylinder in use: signal false for cylinders 0 to 127, signal true for cylinders 128 to 152.
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