 | This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "UDMA" – news · newspapers · books · scholar · JSTOR (September 2014) (Learn how and when to remove this message) |
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 |
See also
- PIO—The first interface type used between devices (mainly hard disks) and the computer.
- Parallel ATA
- Serial ATA
References
- AT Attachment with Packet Interface - 7 Volume 2 - Parallel Transport Protocols and Physical Interconnect (ATA/ATAPI-7 V2) E.2.1.1 Cabling p172
- ^ 80-conductor cable required
- CompactFlash 6.0 Introduction Archived 2010-11-21 at the Wayback Machine