UDMA
Data transfer method for ATA hard drives
The Ultra DMA (Ultra Direct Memory Access, UDMA) modes are the fastest methods used to transfer data through the ATA hard disk interface, usually between a computer and an ATA device. UDMA succeeded Single/Multiword DMA as 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 for CompactFlash), each with its own timing.
Modes faster than UDMA mode 2 require an 80-conductor cable to reduce data settling times, lower impedance and reduce crosstalk.
| Mode | Number | Also called | Maximum transfer rate (MB/s) | Minimum cycle time | Defining standard |
|---|---|---|---|---|---|
| Ultra DMA | 0 | 016.7 | 120 ns | ATA-4 | |
| 1 | 025.0 | 080 ns | ATA-4 | ||
| 2 | Ultra ATA/330 | 033.3 | 060 ns | ATA-4 | |
| 3 | 044.4 | 045 ns | ATA-5 | ||
| 4 | Ultra ATA/660 | 066.7 | 030 ns | ATA-5 | |
| 5 | Ultra ATA/100 | 100.0 | 020 ns | ATA-6 | |
| 6 | Ultra ATA/133 | 133.0 | 015 ns | ATA-7 | |
| 7 | Ultra ATA/167 | 167.0 | 012 ns | CompactFlash 6.0 |
Sources and credits
This article is adapted from the Wikipedia article “UDMA”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- IDE cable 40 pin & 80 pin.jpg by User Smial on de.wikipedia, CC BY-SA 2.0 de
- SANDISK Extreme Pro CompactFlash card 32 GB 90 MBs.jpg by Coyau, CC BY-SA 3.0
Fathomly is not affiliated with or endorsed by the Wikimedia Foundation. Spotted a problem? Tell us.
