Short for Ultra Direct Memory Access, and also known as Ultra ATA, UDMA is a standard developed by Quantum in conjunction with Intel that is twice as fast as the previous DMA interface. UDMA was first introduced in 1998 with the ATA-4 or ATA/ATAPI-4 standard and is capable of transferring data at 33.3 MBps, which is how the UDMA/33 or Ultra DMA/33 names were created. Since its initial release and the approval of new ATA standards, the below UDMA standards are available.
- ATA-5 -- UDMA/66, Ultra DMA/66
- ATA-6 -- UDMA/100, Ultra DMA/100
UDMA/66 and higher are only supported when an 80-wire 40-pin cable is being used. This cable can be distinguished by looking at the ribbon and noticing the amount of wires when compared with a 40-wire cable.