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The Ultra DMA (Ultra Direct Memory Access, UDMA) interface was the fastest method used to transfer data through the ATA controller, usually between the computer and an ATA device. 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.
|Mode||Number||Also called||Maximum transfer
|Minimum cycle time||Defining standard|
|Ultra DMA||0||16.7||120 ns||ATA-4|
|2||Ultra ATA/33||33.3||60 ns||ATA-4|
|4||Ultra ATA/66||66.7||30 ns||ATA-5|
|5||Ultra ATA/100||100||20 ns||ATA-6|
|6||Ultra ATA/133||133||15 ns||ATA-7|
|7||Ultra ATA/167||167||12 ns||CompactFlash 6.0|
- PIO—The first interface type used between devices (mainly hard disks) and the computer.
- Parallel ATA
- Serial ATA