Editing Industry Standard Architecture (section)

=== XT-IDE ===
Before the 16-bit [[ATA/IDE]] interface, there was an 8-bit XT-IDE (also known as XTA) interface for hard disks. It was not nearly as popular as ATA has become, and XT-IDE hardware is now fairly hard to find. Some XT-IDE adapters were available as 8-bit ISA cards, and XTA sockets were also present on the motherboards of [[Amstrad]]'s later XT clones as well as a short-lived line of [[Philips]] units. The XTA pinout was very similar to ATA, but only eight data lines and two address lines were used, and the physical device registers had completely different meanings.  A few hard drives (such as the [[Seagate Technology|Seagate]] ST351A/X) could support either type of interface, selected with a jumper.

Many later AT (and AT successor) motherboards had no integrated hard drive interface but relied on a separate hard drive interface plugged into an ISA/EISA/VLB slot. There were even a few 80486-based units shipped with MFM/RLL interfaces and drives instead of the increasingly common AT-IDE.

[[Commodore International|Commodore]] built the XT-IDE-based peripheral hard drive and memory expansion unit A590 for their [[Amiga 500]] and 500+ computers that also supported a [[SCSI]] drive. Later models – the [[Amiga 600|A600]], [[A1200]], and the [[Amiga 4000]] series – use AT-IDE drives.