Sometimes known as ATA-4, Ultra ATA is a very fast version of the ATA standard for disk drives developed by Quantum corporation in the late 1990’s. The protocol supports a transfer method known as “burst mode,” where the device can seize control of the data bus for a period, allowing very high transfer rates for brief periods. Ultra ATA supports burst mode transfer rates of 33.3 MB per second and requires an Ultra DMA bus protocol known officially as Ultra DMA/33, but also called UDMA, UDMA/33 and DMA mode 33.
