UDMA
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(Redirected fromUltra DMA)
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TheUltra DMA(Ultra Direct Memory Access,UDMA) modes were the fastest method used to transfer data through theATAhard diskinterface,usually between the computer and an ATA device. UDMA succeededSingle/Multiword DMAas the interface of choice between ATA devices and the computer. There are eight different UDMA modes, ranging from 0 to 6 for ATA (0 to 7 forCompactFlash), each with its own timing.
![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/61/IDE_cable_40_pin_%26_80_pin.jpg/220px-IDE_cable_40_pin_%26_80_pin.jpg)
Modes faster than UDMA mode 2 require an 80-conductor cable to reduce datasettling times,lowerimpedanceand reducecrosstalk.[1]
Mode | Number | Also called | Maximum transfer rate (MB/s) |
Minimum cycle time |
Defining standard |
---|---|---|---|---|---|
Ultra DMA | 0 | 16.7 | 120ns | ATA-4 | |
1 | 25.0 | 80 ns | ATA-4 | ||
2 | Ultra ATA/33 | 33.3 | 60 ns | ATA-4 | |
3[2] | 44.4 | 45 ns | ATA-5 | ||
4[2] | Ultra ATA/66 | 66.7 | 30 ns | ATA-5 | |
5[2] | Ultra ATA/100 | 100 | 20 ns | ATA-6 | |
6[2] | Ultra ATA/133 | 133 | 15 ns | ATA-7 | |
7 | Ultra ATA/167 | 167 | 12 ns | CompactFlash6.0[3] |
See also
[edit]- PIO—The first interface type used between devices (mainly hard disks) and the computer.
- Parallel ATA
- Serial ATA