Tagged: data

DVD-ROM (1997 – )

DVD-ROM (Digital Versatile Disc – Read-Only Memory) is a read-only high-capacity optical disc format. DVD-Video is a form of DVD-ROM, but DVD-ROM usually refers to DVD discs for data storage. Microsoft were the first major corporation to release software on DVD-ROM in 1997.

Capacities range from 4.7GB (for a single-sided, single-layer disc) to 17GB (for a double-sided, dual-layer disc).

DVD-ROM drives are backwards compatible with CD-ROM discs, and can read rewritable DVD media such as DVD-R/DVD+R and DVD-RW/DVD+RW.

Since around 2007, DVD drives (along with optical disc drives generally) have been disappearing from laptops and of course were never available in tablets. Despite this, a lot of computer software is still available on DVD-ROM.

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Preservation / Migration

Blu-ray Disc Recordable (BD-R) (2006 – )

Blu-ray Disc Recordable (BD-R) is a write-once high-capacity optical disc, and a type of Blu-ray Disc that can be read in all Blu-ray Disc drives. The similar BD-RE is a rewritable version.

BD-R drives can be found in computers and personal video recorders (PVRs).

Disc capacities are 25 GB for single-layer discs, 50 GB for double-layer discs, 100 GB for triple-layer, and 128 GB for quadruple-layer.

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MiniDVD-R (1997 – )

The MiniDVD-R is a smaller (8cm) version of the DVD-R. MiniDVD-R discs can be used in the same way as 12cm DVD-R discs to hold computer data, but their most common use was in DVD-based camcorders from around 2003 to the early 2010s.

A standard MiniDVD-R could hold 30 minutes of video, with double-layer discs offering 60 minutes (with a compatible camcorder).

The use of MiniDVD-R discs in camcorders made it easier to watch the resulting video on standard tray-loading DVD players (providing the disc was ‘finalised’ in the camcorder first).

Many DVD camcorders could also use other types of DVD discs, such as MiniDVD+R, MiniDVD-RW, MiniDVD+RW and MiniDVD-RAM.

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Phase-change Dual (PD) disk (1995 – 1998)

Introduced by Panasonic in 1995, the Phase-Change Dual (PD) disk is a rewritable optical disc similar to later technologies like CD-RW. They have a capacity of 650MB and could be rewritten 500,000 times.

Like DVD-RAM disks, they are enclosed in a protective cartridge.

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Quantum GoVault (2006 – )

The GoVault is a removable hard disk cartridge system introduced by Quantum in 2006 and aimed at the small business market. The cartridges consist of a 2.5-inch hard disk drive in a rugged case that is claimed can withstand drops of up to 1 metre onto a hard surface. The GoVault dock can be internal (using either the 3.5 or 5.25-inch form factors) or external.

Initial capacities were 40GB, 80GB or 120GB, with 160GB and 320GB versions being released later.

GoVault is intended for data backups, and although more expensive than tape, has the advantage of being capable of being accessed in the same way as any other hard disk drive.

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StorageTek T10000 / T10000 T2 (2006 – )

StorageTek T10000 is a line of magnetic tape formats for high-capacity data storage, typically used with large computer systems and often with a robotic tape library. The T10000 line was first introduced in 2006.

The first two tape drives in the line, the T10000 and T10000B, offered a capacity of 500 GB and 1 TB respectively on the same cartridge. A later version of the cartridge introduced in 2011, the T10000 T2, allowed for capacities of 5 TB and 8.5 TB in the T10000C and T10000D drives.

The T10000 is a cartridge format, containing a single-reel of ½-inch tape, similar to formats such IBM 3480 and Digital Linear Tape. The T10000 uses serpentine recording and the cartridges contain an RFID tag for information such as volume serial numbers.

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DVD-R (1997 – )

DVD-R is a recordable optical disc format based on DVD and developed by Pioneer in 1997. It is supported by most DVD players and is approved by the DVD Forum. It is similar to, but incompatible with, the newer DVD+R standard

A double-sided DVD-R typically has a storage capacity of 4.7 GB but a dual-layer double-sided version with a capacity of 8.5 GB, DVD-R DL, was released in 2005. DVD-R is generally used for non-volatile data storage or video applications. A smaller 8cm version of DVD-R (miniDVD-R) is also available for use in camcorders.

Double-sided DVD-R discs are composed of two 0.6 mm acrylic discs bonded to each other, one containing the laser guiding groove and coated with the recording dye and a silver alloy or gold reflector. On single-sided discs, the unused side is simply a blank to make up the thickness to 1.2mm.

Many DVD drives are hybrid drives (normally labeled ‘DVD±RW’) and can read and write to both DVD-R and DVD+R. However, because the DVD-R format has been in use since 1997, it has had a five-year lead on DVD+R which wasn’t introduced until 2002. As such, older DVD players are more likely to favour the DVD-R standard exclusively.

Unlike DVD+R, DVD-R discs do not need to be formatted before being recorded by a compatible DVD video recorder.

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Preservation / Migration

Jacquard Loom card (1801 – 1990s)

The Jacquard Loom was a mechanical loom for cloth weaving, first demonstrated by Joseph Marie Jacquard in 1801. It used a chain of punched cards laced together to allow the loom to create complex patterns.

Any number of the cards could be chained together into a continuous sequence, with each card corresponding to one row of the design. Each position on the card corresponds to a ‘Bolus’ hook which can either be raised or stopped dependent on whether the hole is punched out of the position on the card or not. The hook raises or lowers the harness, which carries and guides the warp thread so that the weft will either lie above or below it.

Modern Jacquard looms are controlled by computers in place of the original punched cards, and can have thousands of hooks.

Charles Babbage was aware of Jacquard loom cards, and planned to use cards to store programs in his Analytical engine, first described in 1837. Later in the 19th Century, Herman Hollerith used the idea of storing information on cards to create the punched card tabulating machine which he used to input data for the 1890 US Census.

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Business card CD-ROM (1998 – )

Shaped Compact Discs first appeared in the mid-1990s, the first being The Flaming Lips CD single entitled ‘This Here Giraffe’ released in 1995.

Business card size (or credit card size) CD-ROMs followed from around 1998 and were produced by several companies in both the US and Europe. They are generally 80mm wide, and between 58 and 68mm long. They may be rectangular, or may be rounded off to a similar size as the Mini CD.

Capacity is a lot less than that of full-size CD-ROMs, somewhere between 30 and 100 MB, but for the purpose they were originally intended, as an enhanced form of business card, or for distributing company information like annual reports and promotional material, this was sufficient.

They will play in most Compact Disc drives, using the smaller recess on tray-loading drives. They won’t work in slot-loading drives.

A particular type of business card CD-ROM was known as the bootable business card (BBC), and generally contained a distribution of Linux that a computer could be booted from.

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2.5-inch hard disk drive (1988 – )

Hard disk drives consist of one of more rigid disks (or platters) with magnetic heads arranged on a moving actuator arm to read and write data to the surfaces.

The 2.5-inch form factor is one of the two dominant types on the market, with the 3.5-inch form factor being the other. 2.5-inch hard disk drives were introduced in 1988 by PrarieTek and have become most common in laptops and other mobile devices, as well as game consoles such as the PlayStation 3 and Xbox 360.

They are normally 9.5mm high with a single platter, but taller drives with two or more platters have been produced, as well as smaller sizes (a 5mm version by Western Digital was introduced in 2013 for use in UltraBooks).

Whilst not strictly speaking removable media, 2.5-inch hard disk drives form the basis for many external hard disk drives such as those connected by USB, and docks are available to read hard disk drives without installing them.

Solid-state drives using flash memory are beginning to replace hard disk drives for uses where speed, power consumption and durability are more important considerations, such as in tablet computing.

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