The Compaq AlphaStation XP1000 System uses the PCI-ISA bridge chip to provide an Integrated Drive Electronics (IDE) interface to two 16-bit channels. Most of the connections are made on pins that are used for ISA bus transactions as well.
The interface can support up to two devices, drive 0 and drive 1, on each channel (primary and secondary). Each channel has a separate connector on the riser card. Note that the two channels are not truly electrically separated, so simultaneous data transfers are not possible.
The IDE bus can be used for IDE hard disks and for AT Attachment (ATA) Packet Interface (ATAPI) CD-ROMs.
An external PCI interrupt is not used. Instead, the two internal interrups for the primary and secondary channels are routed to internal ISA interrups IRQ14 and IRQ15/