Storage Interfaces

IDE/ATA Evolution

The Integrated Device Electronics/AT Attachment (IDE/ATA) interface is the most common interface found on desktop and home computers. Additionally, it is becoming increasingly available on Dell's PowerEdge servers and PowerVault storage products.

Initially, computer manufacturers sought to integrate the drive controller circuits on the hard disk itself. The hard disk and controller were integrated on a card that plugged into an ISA expansion slot. Soon, the industry realized that the hard disk didn't have to be physically mounted to the card. The controller was moved to the bottom of the hard disk, and the disk and controller assembly were moved to a regular drive bay.

The connection to the system bus was maintained through the use of a cable that ran either directly to a system bus slot, or to a small interface card that plugged into a system bus slot. Technically, these drives were connected directly to the ISA system bus. The official name for the interface, AT Attachment, reflects this, as the IBM® PC/AT was the first PC to use the now-standard 16-bit ISA bus.

The next evolution of the IDE/ATA interface occurred when the IDE/ATA controllers were integrated onto the computer system board. Instead of connecting to a controller "card", the drive is connected directly to the system board. Because of the 16-bit nature of the ISA bus, the IDE/ATA controllers back then were 16 bits wide; this remains true today.