Tagged: magneto-optical

3.5-inch magneto-optical disc (1991 – 2000s)

Magneto-optical (MO) discs were a form of optical disc used for data storage, released commercially in 1985 in a 5.25-inch format, with a 3.5-inch version becoming available in 1991.

The disc consists of a ferromagnetic material sealed beneath a plastic coating. The only physical contact is during recording when a magnetic head is brought into contact with the side of the disc opposite to the laser. By default, MO drives verify information after writing it to the disc, and are able to immediately report any problems to the operating system. This means writing can actually take three times longer than reading, but it makes the media extremely reliable. MO discs are housed in a caddy for protection from dust.

The 5.25-inch discs were available in capacities from 256 MB to 9.2 GB, split over two sides. The drives used the SCSI interface, and mainly saw use in corporate storage and retrieval, such as legal document storage and medical imaging where high reliability, long life, and (at the time) high storage capacity were required. Optical libraries were available to automate loading and storing of the disks.

Their first major use was in the NeXT Computer in 1987, which initially offered a 256 MB 5.25-inch MO drive.

The 3.5-inch discs were single-sided, with capacities ranging from 128 MB to 1.3 GB. They were available with different interfaces such as SCSI, IDE and USB and were more popular with consumers.

As with all removable storage media, the advent of cheap CD/DVD drives and flash memory has made them largely redundant. Magneto-optical disks in particular were expensive when new, and while highly reliable, the slow writing time also was a
drawback.

As of 2010, MO drives were no longer being manufactured.

Sources / Resources

MiniDisc (1992 – 2013)

MiniDisc was a magneto-optical disc format for audio, introduced by Sony in 1992.

MiniDisc, along with the Digital Compact Cassette released the same year, was intended to be a replacement for the Compact Cassette. Sony’s previous attempt to replace the Compact Cassette was Digital Audio Tape (DAT) but this had failed in the consumer market.

MiniDiscs were very popular in Japan but made a limited impact elsewhere. A smaller number of pre-recorded albums were available than other formats, and after around 1995 it faced competition from other recordable formats such as the CD-R.

An incompatible variant for data storage, MD Data, was introduced in 1993 but failed. Later, Hi-MD introduced higher capacity disks, could be used for data and audio, and was compatible with MiniDisc, however Hi-MD itself was discontinued in 2011.

The disc itself is housed in a cartridge with a shutter, and can be recordable (blank) or pre-recorded. Capacities ranged from 60 minutes to 74 or 80 minutes. Data is read to a memory buffer to prevent skipping except under extreme conditions.

The last MiniDisc players were sold in 2013.

Sources / Resources

Preservation / Migration

Hi-MD (2004 – 2011)

Hi-MD was a magneto-optical disk format for audio and data, and a development of the MiniDisc. It was introduced by Sony in 2004.

Most devices using Hi-MD are portable music players and recorders.

It has the same dimensions as MiniDisc, but with a capacity of 1 GB, allowing the use of lossless audio recording. Depending on which of the three native audio codecs are selected, capacity can range from 94 minutes in PCM mode, to 7 hours and 55 minutes in Hi-SP mode, and 34 hours in Hi-LP mode.

Most Hi-MD devices can also record to and play standard MiniDiscs.

The last Hi-MD player was discontinued in 2011.

Gallery

Sources / Resources

MD Data (1994 – early 2000s)

MD Data (which stood for ‘MiniDisc Data’) was a magneto-optical disc format, introduced by Sony in 1994 and based on the same technology as the audio MiniDisc launched in 1992.

Like the MiniDisc, MD Data consisted of a small 65 mm diameter rigid disk enclosed in a caddy with a shutter, and was recordable. Although MD Data disc caddies have the same dimensions as MiniDisc (7 cm x 6.75 cm x 0.5 cm), the caddies have some differences to MiniDiscs such as a different shutter shape, and most MD Data drives could not write to audio MiniDiscs. Some MD Data devices could play the audio from MiniDiscs via the audio-out jack, and some multi-track recorders could record to audio MiniDiscs, but only in 2-track mode.

As with other types of magneto-optical discs, there is a layer of  ferromagnetic material sealed in the disc. To record data, a laser on one side of the disc heats a spot to its Curie point. A magnetic head on the opposing side of the disc can then alter the polarity of the heated spot. When played back, the laser detects the polarisation of the reflected light. Sony claimed that discs can be recorded on repeatedly, up to one million times, and unlike other magneto-optical discs, MD Data disks were rewritten in a single pass.

MD Data discs provided 140 MB of data storage, which for the time was a significant amount for a removable data storage format (for instance, Iomega’s 100 MB Zip Drive was not launched until 1995). However, MD Data was regarded as slow (one user reported it as feeling like a single speed CD-ROM drive) and expensive (with discs around $25 in 1995), and although there was an internal and an external MD Data drive available for computers, it never took off as a computer storage format. This was despite a Sony spokesperson proclaiming on its launch ‘We think it’s the floppy disk of the future’.

Their main use was in a handful of Sony still digital cameras, a Sharp digital camera, Sony document scanners, Sony still video recorders (for medical use during investigative procedures or surgery) and some multi-track audio recording decks from Sony, Yamaha and Tascam.

In 1997, Sony announced the MD Data2 format (also known as MD View), which could hold 650 MB of data but this was only used in a Sony camcorder (the DCM-M1 or MD Discam) introduced in 1999, and even at the time the discs were reportedly difficult to source. Existing MD Data devices could not use the newer MD Data2 discs.

The last product to use MD Data was introduced in 1997, and by 2004 Sony had introduced the Hi-MD format (which was discontinued in 2011) that had a capacity of 1 GB and was compatible with audio MiniDiscs. MiniDiscs themselves lasted until 2013 when the last players were sold.

Sources / Resources

Nintendo 64DD (1999-2000)

Nintendo 64DDThe 64DD (for Dynamic Drive) is a magneto-optical disc system peripheral for the Nintendo 64, and was introduced by Nintendo in 1999.

It was intended to be Nintendo’s answer to the cheaper-to-produce Compact Disc that was used for Sony’s PlayStation. The discs the 64DD were rewritable and had a storage capacity of 64 MB. The games on normal Nintendo 64 ROM cartridges could also hook up with 64DD expansions, for extra levels, minigames, or saving personal data.

It was a commercial failure, and only nine games were released for it. It was never released outside Japan, and was discontinued in 2000.

Sources / Resources

5.25-inch magneto-optical disc (1985 – 2000s)

Magneto-optical (MO) discs were a form of optical disc used for data storage, released commercially in 1985.

The disc consists of a ferromagnetic material sealed beneath a plastic coating. The only physical contact is during recording when a magnetic head is brought into contact with the side of the disc opposite to the laser. By default, MO drives verify information after writing it to the disc, and are able to immediately report any problems to the operating system. This means writing can actually take three times longer than reading, but it makes the media extremely reliable. MO discs are housed in a caddy for protection from dust.

The 5.25-inch discs were available in capacities from 256 MB to 9.2 GB, split over two sides. The drives used the SCSI interface, and mainly saw use in corporate storage and retrieval, such as legal document storage and medical imaging where high reliability, long life, and (at the time) high storage capacity were required. Optical libraries were available to automate loading and storing of the disks.

Their first major use was in the NeXT Computer in 1987, which initally offered a 256 MB 5.25-inch MO drive.

The 3.5-inch discs were single-sided, with capacities ranging from 128 MB to 1.3 GB. They were available with different interfaces such as SCSI, IDE and USB and were more popular with consumers.

As with all removable storage media, the advent of cheap CD/DVD drives and flash memory has made them largely redundant. Magneto-optical disks in particular were expensive when new, and while highly reliable, the slow writing time also was a
drawback.

As of 2010, MO drives were no longer being manufactured.

Sources / Resources