A few early SCSI drives were in fact ST-506 drives with a SCSI to ST-506 controller on the bottom of the drive; however, most SCSI and all ATA drives had built the controller into the drive, thereby eliminating the ST-506 interface in such models.
Однако, большинство SCSI и все ATA имели встроенный контроллер в составе диска и таким образом, в таких моделях исключался интерфейс ST-506.