In the Power Mac G4 Cube, the KeyLargo IC provides an Ultra DMA IDE (integrated drive electronics) channel that is connected to the internal hard disk drive and the CD-ROM or DVD-ROM drive. The KeyLargo IC provides DB-DMA (descriptor-based direct memory access) support for the Ultra DMA interface.
The Ultra DMA IDE interface, also called Ultra-DMA/66 and ATA-5, is an improved version of the EIDE interface.
The internal hard disk drive is connected as device 0 (master) in an ATA Device 0/1 configuration; the CD-ROM drive or DVD-ROM drive is an ATAPI drive and is connected as device 1 (slave).