| Types of storage | | | | moveable read/write head comprising a laser), such |
| Solid-state memory devices | | | | as:pressed CD-ROMs |
| Digital computers, in particular, make use of two | | | | WORMs, CD-R |
| forms of memory known as RAM or ROM and | | | | DVDsmulti-layer DVDs |
| although the most common form today is RAM, | | | | Printing technology |
| designed to retain data while the computer is | | | | Although not a digital storage medium in itself, printing |
| powered on, this was not always the case. Nor is | | | | hard-copies of documents and images remains a |
| active memory the only form used; passive memory | | | | popular means of representing digital data and |
| devices are now in common use in digital cameras. | | | | possibly acquires the qualities associated with original |
| Magnetic, or ferrite core, data retention is dependent | | | | documents especially their potential for endurance. |
| on the magnetic properties of iron and its | | | | More recent advances in printer technology have |
| compounds. | | | | raised the quality of photographic images in particular. |
| PROM, or programmable read-only memory, stores | | | | Unfortunately the permanence of printed documents |
| data in a fixed form during the manufacturing | | | | cannot be easily discerned from the documents |
| process, with data retention dependent on the life | | | | themselves.wet-ribbon inked printersheat sensitive |
| expectancy of the device itself. | | | | papers, such as FAX rolls |
| EPROM, or erasable programmable read-only | | | | NCR and other carbon technologiesink-jet |
| memory, is similar to PROM but can be cleared by | | | | printerswax-based inks eg. DataProducts |
| exposure to ultraviolet light. | | | | SI810water-based inksother basesmono laser |
| EEPROM, or electrically erasable programmable | | | | printerscolour laser printers |
| read-only memory, is the format used by flash | | | | Soft storage technology |
| memory devices and can be erased and rewritten | | | | The short-comings of some storage media is already |
| electronically. These devices tend to be | | | | well recognised and various attempts have been |
| extraordinarily resilient; in a 2005 destructive test, a | | | | made to supplement the permanence of an |
| USB key survived boiling in a custard pie, being | | | | under-lying technology. These "soft storage |
| run-over by a truck and fired from a mortar at a | | | | technologies" enhance their base technology by |
| brick wall. Although physically damaged after the final | | | | applying software or system techniques often within |
| test, some deft soldering restored the device and | | | | quite narrow fields of data storage and not always |
| data was successfully retrieved. | | | | with the explicit intention of improving digital |
| Magnetic media | | | | permanence. |
| Magnetic tapes consist of narrow bands of a | | | | RAID systems |
| magnetic medium bonded in paper or plastic. The | | | | Distributed systems, such as bitTorrentnetworked |
| magnetic medium passes across a semi-fixed head | | | | backup servicespublic archive repositoriesweb-site |
| which reads or writes data. Typically magnetic media | | | | archives |
| has maximum lifetime of about 50 years although this | | | | See also |
| assumes optimal storage conditions; life expectancy | | | | UK Digital Archive Strategy |
| can decrease rapidly depending on storage conditions | | | | References |
| and the resilience and reliability of hardware | | | | ^ Burk, Alan; James Kerr; and Andy Pope. "The |
| components.magnetic tape reelsmagnetic stripe | | | | Credibility of Electronic Publishing". Available at |
| cardsmagnetic cardscassette tapesvideo cassette | | | | web.mala.bc.ca |
| tapes | | | | ^ Sweeny, Latanya. "Information Explosion. Available |
| Magnetic disks and drums include a rotating magnetic | | | | at privacy.cs.cmu.edu |
| medium combined with a movable read/write | | | | ^ Sky One |
| head.floppy diskszip driveshard disks and drums | | | | ^ Adelstein, Peter Z. "Permanence of Digital |
| Non-magnetic mediapunched paper-tapepunched | | | | Information". |
| cardsoptical media (rotating media combined with a | | | | |