Magnetic stripe card (1964 – )

A magnetic stripe card is a means of storing data on a card using a band of magnetic material, which is read when the card is passed by a reading head. They are commonly used for things like bank cards and travel tickets.

They first saw use on the London Underground in 1964, where they were used for travel tickets. They were further developed by IBM into the familiar plastic credit card format, and the standard for credit cards was adopted in the US in 1969, and internationally a couple of years later.

On plastic cards, the magnetic stripe is hot stamped on the plastic, while on cardboard cards, the magnetic stripe is applied with magnetic slurry paint or in the form of a hot foil stripe.

The magnetic stripes are usually either high-coercivity (usually nearly black in colour) or low-coercivity (usually light brown in colour). High-coercivity stripes require higher amount of magnetic energy to encode, and are harder to erase making them suitable for bank cards. Low-coercivity stripes require a lower amount of magnetic energy to record, and hence the card writers are much cheaper but the cards are easier to erase giving them a shorter lifespan. This makes them more suitable for applications such as train tickets.

Cards with magnetic stripes may also contain an integrated circuit (making them ‘smart cards’) with RFID tags or a magnetic field for proximity reading, or metal contacts to electrically connect the card to the reader.

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Punched card (1890 – 1980s)

Punched cards (also known as IBM cards or Hollerith cards) were used to control automated machinery or for data processing and consisted of stiff card with holes in predefined positions to represent data or commands.

Prior to their first use for data processing in the 1890 US census using cards designed by Herman Hollerith, forms of punched cards were used to control Jacquard textile looms and mechanical organs.

The cards used in the 1890 US census had round holes, 12 rows and 24 columns. In 1928, IBM developed the 80 column card, using rectangular holes, and this doubled the data that could be stored on a card. The 80 column card became the dominant type, but other formats were available.

IBM and its competitors developed a variety of machines for creating, sorting, and tabulating punched cards and by the 1950s the punched card had become ubiquitous in industry and government. They were the primary medium for data entry, data storage, and processing even before the advent of the digital computer, and millions were created every day. They were a write-once medium, and groups or ‘decks’ of cards formed programs or collections of data. Users could create cards using a desk-sized keypunch with a typewriter-like keyboard. A typing error generally necessitated repunching an entire card.

During the 1960s however, magnetic tape began to replace punched cards as the primary means for data storage. Even so, punched cards were still commonly used for data entry and programming until the mid-1980s.

The first punched cards were blank, but subsequent cards usually had printing such that the row and column position of a hole could be identified, and cards could also carry other printed information such as logos. Some cards had one upper corner cut so that cards not oriented correctly, or cards with different corner cuts, could be easily identified.

A standard 80 column punched card contains 80 bytes, so 99,981 boxes of 2,000 cards would be required to contain the same amount of data as a single 16 GB microSD card.

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Magnabelt (1961 – 1972)

Magnabelt was a magnetic belt format for dictation, introduced by IBM in 1961 with the IBM Executary 214 dictation machine. The belts were made of mylar with a ferromagnetic material deposited on its recording surface.

Early Executary models used a 4-inch wide belt, while later ones used 3-inch belts. Both desktop and portable models were available.

IBM manufactured Executary machines until 1972.

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IBM PCjr (1984 – 1985)

The IBM PCjr (PC junior) was introduced in early 1984 and was an attempt by IBM to enter the home computer market.

It was not fully compatible with the existing IBM PC, and much software written for the PC did not run on the PCjr, but it did offer built-in colour graphics and 3 voice sound, along with a wireless infra-red keyboard, the ability to use a TV set as a monitor, two joystick ports and two ROM cartridge ports. Plugging in a cartridge caused the PCjr to reboot automatically and run the software. Data could be saved via a 5.25-inch floppy disk drive (only included in the more expensive model).

Sales were slower than expected. One reason given was the inferior ‘chiclet’ keyboard, which made typing difficult (although IBM changed the keyboard in July). Another reason was it’s cost, which was twice as much as a Commodore 64. Through expensive advertising and lower prices, sales picked up during Christmas 1984, but fell sharply afterwards and it was discontinued by March 1985.

USB flash drive (2000 – )

USB memory stickUSB flash drives are a data storage format originally introduced commercially in 2000 by Trek Technology (under the name ThumbDrive) and by IBM (under the name DiskOnKey, developed by M-Systems). The DiskOnKey offered storage of 8 MB, more than five times the capacity of the then-common floppy disk. As the name suggests, they consist of flash memory with, in most cases, a standard type-A USB connection.

USB flash drives are (usually) smaller and faster than floppy disks or CD-ROMs, and are more durable and reliable because they have no moving parts. Additionally, they are immune to magnetic interference (unlike floppy disks), and unharmed by surface scratches (unlike CD-ROMs).

USB flash drives draw power from the computer via the USB connection. Some devices combine the functionality of a digital audio player with USB flash storage; they require a battery only when used to play music.

Some USB flash drives may have novelty housing, or may be integrated into other items such as watches or pens.

Because they can hold so much data in an easily portable (and easily lost) format, from around 2004 versions of USB flash drives with hardware encryption became available alongside standard USB flash drives.

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Preservation / Migration

media stability 1obsolescence 1The biggest risks are data rot in drives unused for many years, physical damage to the disk, lost passwords for encrypted drives, or unsupported encryption software.

IBM Magstar MP 3570 (1996 – 2002)

The IBM Magstar MP 3570 was a magnetic tape cassette format introduced in 1996. It was designed for mid-range computer systems, for the tapes to be handled by automated tape libraries, and to have fast data access.

The format used 8mm wide metal particle tape with 128 tracks. The original tapes, called B-type, had a capacity of 5GB uncompressed. The follow-on C-type tapes had the same capacity, but were faster. The final tape media, called C-XL, had a capacity of 7GB uncompressed.

Slower tape formats with higher capacities proved more successful, and the IBM 3570 technology did not enjoy a large market penetration.

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IBM 3480 (1984 – 2004)

IBM introduced the 3480 tape cartridge format in 1984 for use on the IBM System/370 computers, to replace the existing 9-track tape reel format.

It consisted of a rectangular cartridge containing a single reel of ½-inch chromium dioxide tape. The take-up reel is inside the drive. By employing 18 recording tracks, data transfer was much faster than 9-track tape, and a cartridge could store 200 MB.

Various manufacturers made drives, and tapes were transferable between different manufacturer’s drives.

In 1986, hardware-based data compression allowed for 400 MB per cartridge, renamed as the IBM 3490. This was followed by the IBM 3490E format in 1991, employing 36 tracks, and allowing up to 2400 MB with hardware-based data compression.

The IBM 3480 family of formats was superseded by the IBM 3590 or Magstar family, and the last IBM 3480 family drives were manufactured in 2004.

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9-track tape (1964 – 2003)

9-track computer tape was introduced in 1964 for use with the IBM System/360, replacing 7-track tape. The tape itself is ½-inch wide, with 8 data tracks and one parity track, all parallel.

To load a tape, the protective ring is removed from the outside of the tape reel, and the reel installed on the supply hub. The tape leader is then threaded through the various roller assemblies and onto the take-up reel.

In most drives, a vacuum system provided a physical buffer by storing a short length of tape in the vacuum column under relatively low tension, to avoid damage or stretching of the tape due to tape snatch. Tapes included an end-of-tape (EOT) foil strip. When EOT was encountered, the unit would either halt or rewind the tape onto the supply reel.

9-track tapes commonly had densities of 800, 1600, and 6250 cpi, giving approximately 20 MB, 40 MB and 140 MB respectively on a standard 2,400 feet (730 m) reel.

It was used for over 30 years, but drive production ceased in 2003, tape production having ended in 2002.

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Microdrive (1999 – early 2010s)

Microdrive was a miniature hard-drive format designed to fit in a CompactFlash Type II slot and was launched by IBM in 1999.

Initial capacity was 170 MB, but this eventually increased to 8 GB.

Other manufacturers have released similar drives, usually referred to as 1-inch drives or CompactFlash drives due to trademark issues.

Microdrives were also embedded into devices such as certain iPods and other music devices, and PDAs. Because they are mechanical devices, they are more sensitive to shock and temperature changes than flash-based media,

As of 2011, Microdrives are viewed as obsolete, having been eclipsed by solid-state flash media in storage capacity, durability, physical size, and price.

8-inch floppy disk (1971 – early 1980s)

The 8 inch floppy disk (or diskette) was a magnetic storage disk for data that was introduced commercially by IBM in 1971.

It was designed by a team in IBM as an inexpensive way to load data into the IBM System/370, and was initially simply a read-only bare disk (the ‘Memory Disk’) holding 80 KB of data.

By the time of it’s commercial launch, it had been enclosed in a plastic enveloped lined with fabric, to protect the disk and minimise the problems caused by dust.

The first read-write version was introduced in 1972 by Memorex, and could hold 175 KB on 50 tracks (with 8 sectors per track). It was hard-sectored and had 8 sector holes (and an index hole) on the outer diameter.

Further improvements led to teflon-lubricated fabric liners, teflon-coated disks and an eventual increase in capacity to 1.2 MB in the double-sided double density (DSDD) version in 1977.

It was eventually displaced by the 5.25-inch minifloppy disk introduced in 1976.

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Preservation / Migration

media stability 1obsolescence 1