Editing Digital Data Storage (section)

== History ==
{{proseline|section|date=August 2021}}
[[File:DDS2 tape with scale.jpg|thumb|A DDS-2 cartridge.]]
[[File:DDS Streamer inside.jpg|thumb|DDS Streamer inside]]
[[File:DDS4 Cartritge IMG 8918.jpg|thumb|DDS Cartridges]]
[[File:HP Tape.jpg|thumb|A DAT 72 cartridge]]
[[File:DAT 160 logo.svg|thumb|DAT 160 logo]]
[[File:DAT 72 Tape Drive Front, Wiki, EN.jpg|thumb|DAT-72 tape drive, front panel]]

; DDS-1: Stores up to 1.3 GB uncompressed (2.6 GB [[Data compression|compressed]]) on a 60 m cartridge or 2 GB uncompressed (4 GB compressed) on a 90 m cartridge. The DDS-1 cartridge often does not have the -1 designation, as initially it was the only format, though cartridges produced since the introduction of DDS-2 may carry a -1 designation to distinguish the format from newer formats. A media recognition system was introduced with DDS-2 drives and cartridges to detect the medium type and prevent the loading of an improper medium. From 1993, DDS-1 tapes included the media recognition system marks on the leader tape&mdash;a feature indicated by the presence of four vertical bars after the DDS logo.
; DDS-2: Stores up to 4 GB uncompressed (8 GB compressed) on a 120 m cartridge.
; DDS-3: Stores up to 12 GB uncompressed (24 GB compressed) on a 125 m cartridge. DDS-3 uses [[PRML|PRML (Partial Response Maximum Likelihood)]] to minimize electronic noise for a cleaner data recording.
; DDS-4: DDS-4 stores up to 20 GB uncompressed (40 GB compressed) on a 150 m cartridge. This format is also called DAT 40.
; DAT 72: DAT 72 stores up to 36 GB uncompressed (72 GB compressed) on a 170 m cartridge. The DAT 72 standard was developed by HP and [[Certance]]. It has the same form-factor as DDS-3 and -4 and is sometimes referred to as DDS-5.
; DAT 160: DAT 160 was launched in June 2007 by HP, stores up to 80 GB uncompressed (160 GB compressed). A major change from the previous generations is the width of the tape. DAT 160 uses 8&nbsp;mm wide tape in a slightly thicker cartridge while all prior versions use 3.81&nbsp;mm wide tape. Despite the difference in tape widths, DAT 160 drives can load DAT-72 and DAT-40 (DDS-4) cartridges. Native capacity is 80 GB and native transfer rate was raised to 6.9 MB/s, mostly due to prolonging head/tape contact to 180° (compared to 90° previously).<ref>{{cite web|url=http://www.dat-mgm.com/about |title=DAT Technology |access-date=2013-03-31 |publisher=DAT Manufacturers Group |url-status=bot: unknown |archive-url=https://web.archive.org/web/20130531190032/http://www.dat-mgm.com/about%20DAT/DAT%20technology/ |archive-date=2013-05-31 }}</ref> Launch interfaces were [[Parallel SCSI]] and [[USB]], with [[Serial Attached SCSI|SAS]] interface released later.
; DAT 320: In November 2009 HP announced the DAT-320 standard, which stores up to 160 GB uncompressed (marketed as 320 GB assuming 2:1 compression) per cartridge. Native transfer rate was raised to 12 MB/s.

=== Generations ===
{| class="wikitable" style="text-align:right"
|+ DDS generations
! Format
! Date
! abbr="Width" | Tape<br />width<br/>(mm)
! abbr="Track" | Track<br />pitch<br />(μm)
! abbr="Length" | Tape<br />length<br />(m)
! abbr="Capacity" | Native<br />capacity<br />(GB)
! abbr="Compressed" | Capacity assuming<br />2:1 compression<br>(GB)
! abbr="RPM" | Drum rotation<br />speed<br />(RPM)
! abbr="Speed" | Data transfer<br />speed<br />(MB/s)
|-
! DDS-1
| 1989
| 3.81
| 13.6
| 60/90
| 1.3/2.0
| 2.6/4
| 2000, 2551
| 0.183
|-
! DDS-2
| 1993
| 3.81
| 9.1
| 120
| 4.0
| 8
| 4000, 4400, 5737, 8500
| 0.360-0.720
|-
! DDS-3
| 1996
| 3.81
| 9.1
| 125
| 12.0
| 24
| 3825, 4252
| <1.5
|-
! DDS-4
| 1999
| 3.81
| 6.8
| 150
| 20.0
| 40
| 11400
| 1.0-3.2
|-
! DAT-72
| 2003
| 3.81
| 5.4
| 170
| 36.0
| 72
| 8609.7, 10000
| 3.2
|-
! DAT-160
| 2007
| 8
| 6.8
| 154
| 80
| 160
| 6457
| 6.9
|-
! DAT-320
| 2009
| 8
|
| 153<ref>{{cite web |url= http://h30094.www3.hp.com/product/sku/10209877/mfg_partno/Q2032A |title= HP DAT 320 320GB Data Cartridge - DAT & DDS tape cartridges - HP: Q2032A |publisher= Hewlett-Packard |access-date= 2013-12-31 |archive-url= https://web.archive.org/web/20140101091210/http://h30094.www3.hp.com/product/sku/10209877/mfg_partno/Q2032A |archive-date= 2014-01-01 |url-status= dead }}</ref>
| 160
| 320
|
| 12
|-
! (Gen 8)
| canceled
| 8
|
|
| ~300
| ~600
|
| ≥16
|}

=== Future ===
The next format, Gen 8, was canceled.{{cn|date=October 2022}}