Dictionary.net

/ul'tr* D M A/ (Or "Ultra DMA", "UDMA", "Ultra-ATA","Ultra-DMA/33") A development of the Advanced TechnologyAttachment specifications which gives nearly twice themaximum transfer speed of the ATA-3 standard (PIO Mode 4).ATA-4 Extensions Ultra DMA/33 Synchronous DMA Mode maximumburst transfer rates:Mode Cycle Time Transfer RatensMB/s0 235 161 160 242 120 33This is achieved by improving timing windows in the protocolon the ATA interface; reducing propagation delays bypipelining data transfers and transferring data insynchronous (strobed) mode.Developed by Quantum Corporation, ATA-4 has been freelylicensed to manufacturers and is supported by IntelCorporation.