Tagged: digital

5.25-inch ‘flippy’ disk (1976 – mid 1980s)

Flippy disk was a nickname given to single-sided floppy disks that had a second write-enabled notch cut into the sleeve so that the second side could be written to by a single-sided disk drive. Generally, these were 5.25-inch minifloppy disks, but 8-inch floppy disks could be modified in the same way, and this was possible because most of the openings on the sleeve of the disk were duplicated on both sides. It was a way of doubling the capacity of a floppy disk at a time when disks were expensive, although of course they had to be removed from the drive and turned over to access the extra capacity.

When the 5.25-inch minifloppy disk was introduced in 1976, all drives were single-sided. Double-sided drives were introduced in 1978, but suffered from early reliability problems. It wasn’t until 1982 that double-sided drives were supported by IBM PC-DOS in version 1.1. Drives such as Apple’s Disk II and the Commodore 1541 remained single-sided.

The second write-enabled notch could be made by hand, or special ‘disk doubler’ rectangular hold puncher could be bought to do the job. Flippy disks were also sold ready-made, and software was distributed on flippy disks that might have different programs on each side, or the same program but for different operating systems. Flippy disks sold for use in double-sided drives needed to have two index holes on either side of the hub hole.

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Open reel instrumentation and data logging tape (1949 – 2000s)

Magnetic tape was first used for data logging and instrumentation recording in 1949, when Jack Mullins installed modified Ampex Model 300s at Point Mugu Naval Air Station and at Edwards Air Force Base, both in southern California.

Tape has been heavily used since then for military, industrial, government and research applications. The Inter-Range Instrumentation Group (IRIG) set the standards for instrumentation tape recorders.

Instrumentation recorders were built to much more stringent standards than other tape recorders, and recorders that used direct, FM and PCM recording have been available.

On ¼-inch wide tape, there are typically 4 tracks, whereas on ½-inch tape there were 7, or sometimes even 14, tracks. On 1-inch tape, there were 14 or 28 tracks. Tape is usually wound on the reel with the recording surface facing towards the hub (the opposite of audio tape). Metal NAB reels were often used, for reels between 10.5 and 16-inches, but 7-inch plastic reels with cine spindle hubs have also been used.

Instrumentation recorders also used tape in cassette form, including systems that recorded onto S-VHS tape, and the Digital Instrumentation Recorder from Sony that used the SD1 cassette.

Instrumentation and data logging systems now use hard disks or flash memory for storage.

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Digital Data Storage (DDS) (1989 – 2007)

Digital Data Storage (DDS) was introduced in 1989, and used a version of Digital Audio Tape (DAT) for storing data.

DDS used helical scanning on magnetic tape, and stored between 1.3 GB in the first generation (DDS-1) and 36 GB uncompressed on the fifth generation (DAT 72) launched in 2003.

During its life, DDS competed against formats such as Linear Tape-Open (LTO), Advanced Intelligent Tape (AIT), VXA, and Travan, and over 18 million DDS drives were sold.

Generally, DDS drives can read and write to media of one or perhaps two previous generations only, so DDS-4 drives cannot read or write from DDS-1 tapes. DDS drives cannot read or write to media from later generations.

Two later generations (DDS-160 and DDS-320) both use 8mm wide tape in a slightly thicker cartridge, whereas the first five generation of DDS used 3.81 mm tape (often labelled as 4mm DDS).

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Preservation / Migration

media stability 3obsolescence 3Whilst DDS drives are still available secondhand, a single drive cannot read more than three generations of DDS.

The earliest tapes are now nearly 30 years old


DVCPRO (1995 – early 2010s)

DVCPRO (also known as DVCPRO25 or D-7) is a variation of the DV format, and was introduced by Panasonic in 1995 for professional and broadcast use.

In common with all DV formats, DVCPRO uses tape that is ¼-inch (6.35 mm) wide, but DVCPRO uses metal particle (MP) tape rather than metal evaporate. DVCPRO also adds an analogue audio cue track and a control track to make editing easier.

DVCPRO50 was introduced in 1997 and used two DV codecs in parallel, doubling the data rate over the original DVCPRO to 50 Mbps. DVCPRO50 decks can use DVCPRO tapes, but the tape is run at twice the speed so capacity is halved.

In 2000, Panasonic launched DVCPRO HD for high-definition recording. This had a data rate of 100 Mbps and competed with Sony’s HDCAM.

Panasonic stopped selling equipment using video tape around 2013.

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Memory Stick Micro (M2) (2006 – 2009)

Memory Stick Micro (M2) was the smallest form factor of the Sony Memory Stick family. It was introduced as a joint venture with SanDisk in 2006 and is just one-quarter of the size of the Memory Stick Duo. Typical uses include PDAs and mobile phones.

Adaptors were available to allow Memory Stick Micro cards to be used in Memory Stick and Memory Stick Duo slots, and Sony produced an M2 to USB adaptor.

Cards were available from 64 MB to 16 GB capacities.

In 2009, Sony announced that Sony Ericsson phones would use microSD cards instead of Memory Stick Micro, and by 2011, the Memory Stick Micro was no longer available on the Sony UK website.

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3.25-inch floppy disk (1983 – mid-1980s)

The 3.25-inch disk was a floppy disk introduced in 1983 for use in the Tabor TC 500 Drivette disk drive. It was a double-sided disk, with an unformatted capacity of 500 KB.

It was similar in design to the 5.25-inch minifloppy disk, and in fact the drive could replace the 5.25-inch disk drive in a PC using the same cable. In addition to the Tabor Drivette, there was a prototype 3.25-inch disk drive system for the Coleco Adam computer (that at that time was using High Speed Digital Data Pack tape drives) and a 3.25-inch drive was used in the rare Seequa Chameleon 325 computer.

Producers of the disks included Tabor, Dysan, and 3M. However, Dysan seems to have been the main producer of disks, which it labelled as the ‘Flex Diskette’, since like the 5.25-inch disk, the disk’s envelope was flexible.

The 3.25-inch disk came about at a time when there were a number of competing designs of microfloppy disk, such as the 3.5-inch microfloppy and the 3-inch Compact Floppy, and it doesn’t seem to have lasted very long in the marketplace.

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Preservation / Migration

media stability 5obsolescence 5

Ultra Density Optical (UDO) (2003 – )

Ultra Density Optical (UDO) is an optical disc data storage format that uses phase-change, and blue laser technology (similar to Blu-ray) to store substantial amounts of data on a disc in a cartridge very similar to the older 5.25-inch magneto-optical disc format that it was developed to replace.

UDO discs were first announced by Sony in 2000, and launched by Sony and Plasmon in 2003 with a capacity of 30 GB. UDO 2 was launched in 2007 with a capacity of 60 GB.

UDO discs are available in rewritable format, or as write once in which case the phase change method used means the data cannot altered once written (True WORM) making it very stable for long-term storage. A third format became available in 2005, Compliant WORM, that allows specific data on the disc to be destroyed while leaving other files intact.

As of 2017, UDO drives and discs are still available but since 2008 all brands of UDO disc have been manufactured by Mitsubishi in Japan.

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2-inch floppy disk (LT-1) (1989 – early 1990s)

The 2-inch LT-1 disc was introduced in 1989 for use in the Zenith Minisport notebook computer, the only device that used it. Although very similar to the 2-inch Video Floppy, the two discs are not interchangeable.

The Zenith Minisport was a very lightweight laptop, with good battery life and DOS 3.3 built into ROM for fast booting. It came with 1 or 2 MB of RAM, and except for the HD version did not have a hard drive.

The LT-1 discs, which were made by Fujifilm, had a capacity of 793 KB, similar to the double-sided, double-density 3.5-inch microfloppy disk, but a lot less than the high-density 3.5-inch microfloppy disk that was becoming the industry standard. Because the LT-1 discs were only used in one model of computer, they were more expensive than other disc designs, and there was no way to read the discs on other devices.

To get around the problem of file transfer due to the unusual disc design, an external 3.5-inch microfloppy disk drive was available, and the Minisport could also transfer files via serial cable to another PC using a program called FastLynx.

The Minisport only seems to have been produced for a couple of years.

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Roland Music Style Card (1989 – 1991)

The Roland Music Style Card was a ROM card containing programmed music rhythms to extend those available in the E-series ‘intelligent synthesisers’ made by Roland.

The first of the ‘intelligent synthesisers’ was the E-20, released by Roland in 1988 as the first product of Roland’s new European arm, and was aimed at the high-end home market. A number of variations of the first-generation E-series were released, such as the cut-down E-5, and the enhanced E-30 and Pro-E (an ‘intelligent arranger’).

For the first generation of the E-series, the cards were prefixed with TN-SC1 and there were 14 Music Style Cards in the first series released between 1989 and 1991.

There was a subsequent series of Music Style Cards with a slightly different shape and prefixed TN-SC2 for later E-series synthesisers such as the E-35, E-56 and E-70.

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DASH (Digital Audio Stationary Head) (1982 – mid-1990s)

Sony introduced the DASH (Digital Audio Stationary Head) in 1982 for use in professional recording studios. The DASH system could record two-channel audio on ¼-inch tape, or 24 or 48 tracks onto ½-inch tape, and DASH recorders were produced by Sony, Studer and TASCAM.

The tape itself looked identical to standard NAB open reel analogue tape, but tape for use in DASH and the competing (and incompatible) ProDigi format systems used metal-particle tape which was not suitable for use in analogue systems due to the faster wear on the heads. Several companies produced open reel metal-particle tape for digital audio systems, and some examples included 3M Scotch 275, Ampex 467, EMTEC 931 and Sony own-brand tape. Metal-particle tape was even more expensive than oxide-based tape for analogue systems.

Unlike some other digital audio recording systems using tape such as DAT or U-Matic which used helical scanning, the DASH and ProDigi systems used a stationary recording head.

The audio was encoded as PCM, and included error correction, and all DASH recorders were capable of using 16-bit resolution with a 44.1 or 48 kHz sampling rate, with a couple of models capable of 24-bit 48 kHz operation.

DASH and ProDigi were the two main open-reel digital audio recording systems in use from the early-1980s to the mid-1990s, but eventually the falling price of hard-disk space, as well as more compact systems such as ADAT, made them less viable.

Although DASH was a digital system, it still had the disadvantage of having to wind through the tape to find a particular point, and wear could still be a problem. Poorly maintained machines or tape, dust, or fingerprints could render tapes unusable despite the error correction system.

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Preservation / Migration

media stability 5obsolescence 5