Editing UDMA

{{Short description|Data transfer method for ATA Hard drives}}
{{For|the main article about the interface|Parallel ATA}}
{{refimprove|date=September 2014}}

The '''Ultra DMA''' ('''Ultra Direct Memory Access''', '''UDMA''') modes are the fastest methods used to transfer data through the [[Parallel ATA|ATA]] [[hard disk]] [[Interface (computing)|interface]], usually between a computer and an ATA device. UDMA succeeded [[Single word DMA|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.

[[File:IDE cable 40 pin & 80 pin.jpg|thumb|80-conductor cable used for modes faster than UDMA 2 on the left compared to a 40-conductor cable]]
Modes faster than UDMA mode 2 require an 80-conductor cable to reduce data [[settling time]]s, lower [[electrical impedance|impedance]] and reduce [[crosstalk]].<ref>[https://archive.org/stream/SCSISpecificationDocumentsATAATAPI/ATA_ATAPI/AT%20Attachment%20with%20Packet%20Interface%20-%207%20Volume%202%20-%20Parallel%20Transport%20Protocols%20and%20Physical%20Interconnect%20%28ATA_ATAPI-7%20V2%29%20Revision%204b#page/n189/mode/2up AT Attachment with Packet Interface - 7 Volume 2 - Parallel Transport Protocols and Physical Interconnect (ATA/ATAPI-7 V2) E.2.1.1 Cabling p172]</ref>

{| class="wikitable" style="text-align:center"
|+ Transfer modes
! Mode || Number || Also called || Maximum transfer<br/>rate (MB/s) || Minimum<br/>cycle time || Defining<br/>standard
|-
| rowspan=8 | Ultra DMA
| 0 || || {{0}}16.7|| 120 [[nanosecond|ns]] || [[ATA-4]]
|-
| 1 || || {{0}}25.0|| {{0}}80 ns || ATA-4
|-
| 2 ||Ultra ATA/33{{0}}|| {{0}}33.3|| {{0}}60 ns || ATA-4
|-
| 3<ref name="80c">80-conductor cable required</ref> || || {{0}}44.4|| {{0}}45 ns || [[ATA-5]]
|-
| 4<ref name="80c" /> ||Ultra ATA/66{{0}}|| {{0}}66.7|| {{0}}30 ns || ATA-5
|-
| 5<ref name="80c" /> ||Ultra ATA/100|| 100{{0|.0}}|| {{0}}20 ns || [[ATA-6]]
|-
| 6<ref name="80c" /> ||Ultra ATA/133|| 133{{0|.0}}|| {{0}}15 ns || [[ATA-7]]
|-
| 7 || {{nobr|Ultra ATA/167}} || 167{{0|.0}} || {{0}}12 ns || [[CompactFlash]] 6.0<ref>[http://compactflash.org/2010/cf-6-0-introduces-industry-leading-performance-and-feature-enhancements/ CompactFlash 6.0 Introduction] {{Webarchive|url=https://web.archive.org/web/20101121233926/http://compactflash.org/2010/cf-6-0-introduces-industry-leading-performance-and-feature-enhancements/ |date=2010-11-21 }}</ref>
|}

== See also ==
* [[Programmed input/output|PIO]]—The first interface type used between devices (mainly hard disks) and the computer.
* [[Parallel ATA]]
* [[Serial ATA]]

==References==
<references />

[[Category:AT Attachment]]