Editing Computer data storage (section)

=== Other storage media or substrates ===
; Vacuum-tube memory: A [[Williams tube]] used a [[cathode-ray tube]], and a [[Selectron tube]] used a large [[vacuum tube]] to store information. These primary storage devices were short-lived in the market, since the Williams tube was unreliable, and the Selectron tube was expensive.

; Electro-acoustic memory: [[Delay-line memory]] used [[Longitudinal wave|sound waves]] in a substance such as [[mercury (element)|mercury]] to store information. Delay-line memory was dynamic volatile, cycle sequential read/write storage, and was used for primary storage.

; [[Optical tape]]: is a medium for optical storage, generally consisting of a long and narrow strip of plastic, onto which patterns can be written and from which the patterns can be read back. It shares some technologies with cinema film stock and optical discs, but is compatible with neither. The motivation behind developing this technology was the possibility of far greater storage capacities than either magnetic tape or optical discs.

; [[Phase-change memory]]: uses different mechanical phases of [[phase-change material]] to store information in an X–Y addressable matrix and reads the information by observing the varying [[electrical resistance]] of the material. Phase-change memory would be non-volatile, random-access read/write storage, and might be used for primary, secondary and off-line storage. Most rewritable and many write-once optical disks already use phase-change material to store information.

; [[Holographic data storage]]: stores information optically inside [[crystal]]s or [[photopolymer]]s. Holographic storage can utilize the whole volume of the storage medium, unlike optical disc storage, which is limited to a small number of surface layers. Holographic storage would be non-volatile, sequential-access, and either write-once or read/write storage. It might be used for secondary and off-line storage. See [[Holographic Versatile Disc]] (HVD).

; [[Molecular memory]]: stores information in [[polymer]] that can store electric charge. Molecular memory might be especially suited for primary storage. The theoretical storage capacity of molecular memory is 10&nbsp;terabits per square inch (16&nbsp;Gbit/mm<sup>2</sup>).<ref>{{Cite web|url=https://www.sciencedaily.com/releases/2009/02/090219141438.htm|title=New method of self-assembling nanoscale elements could transform data storage industry|archive-url=https://web.archive.org/web/20090301235710/https://www.sciencedaily.com//releases//2009//02//090219141438.htm|archive-date=1 March 2009|website=sciencedaily.com|date=1 March 2009|access-date=18 June 2011}}</ref>

; Magnetic photoconductors: store magnetic information, which can be modified by low-light illumination.<ref name="Náfrádi 2016"/>

; [[DNA digital data storage|DNA]]: stores information in DNA [[nucleotide]]s. It was first done in 2012, when researchers achieved a ratio of 1.28&nbsp;petabytes per gram of DNA. In March 2017 scientists reported that a new algorithm called a DNA fountain achieved 85% of the theoretical limit, at 215&nbsp;petabytes per gram of DNA.<ref>{{cite news|last1=Yong |first1=Ed|title=This speck of DNA contains a movie, a computer virus, and an Amazon gift card|url=https://www.theatlantic.com/science/archive/2017/03/this-speck-of-dna-contains-a-movie-a-computer-virus-and-an-amazon-gift-card/518373/|access-date=3 March 2017|work=The Atlantic|url-status=live|archive-url=https://web.archive.org/web/20170303010826/https://www.theatlantic.com/science/archive/2017/03/this-speck-of-dna-contains-a-movie-a-computer-virus-and-an-amazon-gift-card/518373/|archive-date=3 March 2017}}</ref><ref>{{cite web|title=Researchers store computer operating system and short movie on DNA|url=https://phys.org/news/2017-03-short-movie-dna.html|website=phys.org |access-date=3 March 2017|url-status=live|archive-url=https://web.archive.org/web/20170302221126/https://phys.org/news/2017-03-short-movie-dna.html|archive-date=2 March 2017}}</ref><ref>{{cite web|title=DNA could store all of the world's data in one room|url=https://www.science.org/content/article/dna-could-store-all-worlds-data-one-room|publisher=Science Magazine|access-date=3 March 2017|date=2 March 2017|url-status=live|archive-url=https://web.archive.org/web/20170302225525/http://www.sciencemag.org/news/2017/03/dna-could-store-all-worlds-data-one-room|archive-date=2 March 2017}}</ref><ref>{{cite journal|last1=Erlich|first1=Yaniv|last2=Zielinski|first2=Dina|title=DNA Fountain enables a robust and efficient storage architecture|journal=Science|date=2 March 2017|volume=355|issue=6328|pages=950–954|doi=10.1126/science.aaj2038|pmid=28254941|url=https://zenodo.org/record/889697|bibcode=2017Sci...355..950E|s2cid=13470340}}</ref>