ST-506/ST-412
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The ST-506 and ST-412 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-4
Seagate ST506 5¼-inch HDD with cover removed
2.5" 6495 MB IDE drive next to a 5.25" full-height 111 MB MFM drive
Western Digital WD1006
Control connector
Parallel ATA
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Parallel ATA, originally AT Attachment, also known as Integrated Drive Electronics, is a standard interface designed for IBM PC-compatible computers. It was first developed by Western Digital and Comp
ST-506/ST-412
…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 HDD was the first 5.25 inch hard disk drive, introduced in 1980 by Shugart Technology (now Seagate Technology). It stored…
Two ATA motherboard sockets above, with an ATA connector below
IDE Connectors in PC Chips M925LR Pentium 4
Example of a 1992 80386 PC motherboard with nothing built in other than memory, keyboard, processor, cache, realtime clock, and slots. Such basic motherboards could have been outfitted with either the ST-506 or ATA interface, but usually not both. A single 2-drive ATA interface and a floppy interface was added to this system via the 16-bit ISA card.
44-pin PATA connector on a 2.5-inch drive, with 4 pins on the side for Master/Slave selection.