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For the main article about the controller, see Parallel ATA.

The Ultra DMA (Ultra Direct Memory Access, UDMA) interface was the fastest method used to transfer data between the computer (through the ATA controller) and an ATA device until Serial ATA. UDMA succeeded Single/Multiword DMA as the interface of choice between ATA devices and the computer. There are 8 different UDMA modes, ranging from 0 to 6 for ATA, 0 to 7 (for CompactFlash), each with its own timing.

Transfer Modes
Mode Number Also called Maximum transfer
rate (MB/s)
Defining standard
Ultra DMA 0 16.7 ATA-4
1 25.0 ATA-4
2 Ultra ATA/33 33.3 ATA-4
3 44.4 ATA-5
4 Ultra ATA/66 66.7 ATA-5
5 Ultra ATA/100 100 ATA-6
6 Ultra ATA/133 133 ATA-7
7 Ultra ATA/167 167 CompactFlash 6.0[1]

See also[edit]


  1. ^ CompactFlash 6.0 Introduction