Coleco Adam High Speed Digital Data Pack (1983 – 1985)

The Coleco Adam was a home computer introduced by Coleco in 1983. It was available as a standalone computer, or could be bought as an expansion pack for the ColecoVision game console.

Like other home computers of the time, the Coleco Adam used a tape drive as one means to store programs and data, but this was not a standard Compact Cassette drive. The dual ‘Adam High Speed Digital Data Pack’ tape drives used a slightly modified type of Compact Cassette that ran at much higher speed than usual, had a different configuration of holes in the shell, and used thicker tape. These could store 256 KB, and ran at 20 inches per second (ips) when reading/writing and and 80 ips when rewinding. Blank Digital Data Packs  were supplied pre-formatted and could not be formatted by the user.

As well as the Digital Data Pack drives, the Adam had a ROM cartridge slot that accepted all ColecoVision cartridges as well as its own (it could play ColecoVision games even as a standalone computer). Later in production, a 5.25-inch disk drive was made available as an accessory.

The Coleco Adam had other unusual features such as a dedicated daisywheel printer (that also contained the power supply), built-in word-processing software, and the CP/M operating system as an option.

Unfortunately, delays in its introduction, and build quality issues led to it being discontinued in 1985. One particular problem was that tapes left in the drives or near the machine when it was turned on could suffer data loss.

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Compact Cassette Type IV (Metal) (1979 – late 1990s)

The Type IV or metal-formulated Compact Cassette was introduced in 1979 by 3M under the trade name Metafine, and addressed a number of problems with previous tape formulations.

Standard Compact Cassettes (Type I or ferric-oxide) typically had poor high frequency definition, with pervasive tape noise (hiss). Type II (chromium dioxide) had much better frequency reproduction and very low noise but at the expense of some output level and low frequency solidity. Type III (ferro-chrome) was an attempt to restore some low frequency firmness but whilst Type III worked as a concept, it was not enough of an improvement to be taken up by the market.

Type IV was a completely new formulation using pure metal particles instead of metal oxides. This created a hard-wearing tape with superior frequency response and greater dynamic range.

It also had some disadvantages such as excess wear on tape heads, and they were expensive to buy. By the mid-1980s, metal tape did begin to catch on and was adopted by a lot of enthusiasts.

For tape recording equipment that was capable of using metal tape, there were extra indentations in the top of the cassette to identify it as Type IV and select the correct bias and equalization. On equipment without metal tape settings, it was possible to playback cassettes, but recordings would not be successful.

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Tape-slide set (1960s – 1980s)

Tape-slide sets usually consist of a set of 35mm slides with accompanying audio on Compact Cassette. These were most often used for education and training purposes, but have also been used for tourism and art.

Later slide projectors could be automatically advanced by an inaudible tone on the tape, but often the presenter would hear an audible tone and have to advance to the next slide manually. On some tapes, one side would have audible tones for the older projectors, and the other side would have the subaudible tones for automatic projectors, while others combined both types on the same side.

At a time when tape players and slide projector were common, they were a relatively inexpensive way to produce educational materials, and could be viewed by a large group. Self-contained units such as the Kodak Caramate were available for instances where a small number of people wanted to view a presentation, and these included a slide projector, a cassette player, and a built-in screen.

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Filmstrip (1940s – 1980s)

Filmstrips were a form of multimedia usually used for training or educational purposes, combining a sound recording with a strip of still images on 35mm film.

From the 1940s to 1980s, filmstrips provided an easy and inexpensive alternative to 16mm projector educational films, requiring very little storage space and being very quick to rewind for the next use.

Like 16 mm film, a filmstrip was inserted vertically down in front of the filmstrip projector aperture, rather than horizontally as in a slide projector. Therefore, the frame size is smaller than normal 35 mm film. Two image frames of a filmstrip take up the same amount of space as a single 35mm frame, including its guard band, so that a 25 exposure 35mm film can contain fifty filmstrip images.

Typically, a filmstrip’s running time was between ten and twenty minutes and narration was provided by a 33⅓ rpm record, or from the early 1970s, a Compact Cassette tape. At the appropriate point, a tone would sound, signaling the instructor to advance to the next frame. In the 1970s, filmstrips projectors were produced that could automatically advance the film when a 50 Hz subaudible tone recorded on the tape was detected. On some tapes, one side would have audible tones for the older projectors, and the other side would have the subaudible tones for the newer automatic projectors, while others combined both types.

By the 1980s, the increasing affordability of video players meant a decline in filmstrip use.

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Music cassette (1965 – 2003)

Music cassettes (Musicassettes or MC for short) were Compact Cassettes used for pre-recorded music distribution.

Pre-recorded music cassettes were available in Europe from 1965, initially through the Philips Record Company, and as fidelity improved they became one of the predominant formats for pre-recorded music between the late 1970s and early 1990s. The Advent 201 introduced in 1971 was the first Compact Cassette recorder to use Dolby type B noise reduction and chromium dioxide (CrO2) tape, resulting in the format being taken more seriously for music use, and starting the era of high fidelity cassettes and players

By the late 1970s, music cassettes supplanted the 8-Track as the main in-car entertaiment format, and in the 1980s, its popularity grew as a portable music format with the introduction of personal stereo systems based on the Sony Walkman. Sales of music cassettes overtook those of LPs in 1984.

Between 1985 and 1992, the music cassette was the most popular format in the UK for album sales, and cassette singles were introduced to compete against the 7-inch single, but were not as successful.

Around 1992, sales of music cassettes were overtaken by the Compact Disc, and this was also the year that sales of music cassettes peaked. By 2001, music cassettes accounted for just 4% of pre-recorded music sales, with most major US music companies discontinuing by the end of 2003.

Cassettes remained popular for in-car entertainment audio into the 2000s, as cassettes and their players were typically more rugged and resistant to dust, heat, and shocks than Compact Disc, but the reduction of in-car noise levels, the general heightening of consumer expectations meant that during the 2000s, the CD player replaced the cassette player as the default audio component in the majority of new vehicles in Europe and America.

In recent years, music cassettes have seen a small revival with some independent record labels issuing releases in this format due to its low cost and the difficulty in sharing tape music over the internet.

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Compact Cassette Type II (Chrome / High-Bias) (1970 – 2000s)

The Type II or chromium dioxide Compact Cassette was introduced to the market in 1970 by BASF.

Chromium dioxide provided an increase in high frequency response over the often rather muffled tone of the existing Type I ferric cassette, but took a while to take off as mainstream audio equipment available in the 1970s couldn’t make full use of the improvement in sound quality and it was only in the 1980s that chrome tapes become mass market.

Recording onto blank chromium dioxide tape ideally required the use of high-bias, and an EQ setting of 70μS. Pre-recorded music cassettes were often made to be played at 120μS (the same as ferric tape) to ensure wider compatibility.

An alternative formulation based around a cobolt / iron oxide was introduced in the mid-1970s and by the 1990s even BASF moved onto this substitute for chrome, although it was still labelled as chrome and was still high-bias.

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1+1 music cassette (early 1980s)

The 1+1 music cassette was a short-lived variation on the usual music cassette by Island Records in the early 1980s. It consisted of the complete album on both sides of the cassette, but Side 2 could be recorded over by the owner of the cassette (and the record-protect tab for Side 2 was left intact for this purpose)

As the cassette used chrome tape, this effectively meant that for the price of the album, the purchaser also got space to record a second album on good quality tape. Being chrome tape meant that ideally the tape should be recorded at a higher bias setting than ferric tape, but if this facility was not available on the tape recorder, the recording would not come out well.

Side 1 was also on chrome tape, but used ferric equalisation, so could be played back on any tape player.

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Streamer cassette (late 1980s – late 1990s)

Streamer cassettes were a variant of the Compact Cassette, specially designed for data storage (but different from standard cassettes used for data storage with early home computers) and had  a typical tape speed of 90 inches per second. Cassette tape streamers could be used with personal computers to make hard disk back ups.

They look almost identical to a normal Compact Cassette with the exception of a notch about ¼-inch wide and deep situated on the top edge of the cassette. Streamer cassettes also have a re-usable write-protect tab on only one side of the top edge of the cassette, with the other side of the top edge having either only an open rectangular hole, or no hole at all.

The whole of the ⅛-inch tape width is used for data, so there is only one ‘side’, but data is stored in four tracks in serpentine fashion.

Streamer cassettes could hold anywhere from 50 to 160 MB of data.

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Compact Cassette Type III (Ferro-chrome) (mid 1970s – early 1980s)

Ferro-chromium or Type III Compact Cassettes were produced between the mid-1970s and early 1980s, and were an attempt to rectify the problems inherent in Type I and Type II cassettes. Type I (Ferric) tapes had poor definition in the higher treble regions whereas Type II (Chrome) tapes were quite flimsy around the bass regions of the sound spectrum. Type III combined a layer of ferric oxide with a layer of chromium dioxide. Theoretically, this would offer the user the enhanced high frequency definition of chrome, plus the fuller bass of the regular ferric tape.

The bias of Type III was somewhere between Type I and Type II, but mass market tape decks now had the dilemma of whether or not to add a Type III bias setting to their machines, and there was not enough of an improvement to warrant this. When Type IV metal tape arrived in 1979, ferrichrome was rendered technically pointless as well as technically flawed.

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Compact Cassette for data (1975 – late 1980s)

Early microcomputers often used punched tape for data storage, until in 1975 Jerry Ogdin and Les Solomon co-authored an article in Popular Electronics magazine about using inexpensive Compact Cassettes with audio tones to represent the binary data.

Many home computers of the late 1970s and early 1980s subsequently used cassettes for data storage as a cheaper alternative to paper tape or the floppy disks increasingly used in high-end microcomputers.

Typical speeds of loading were from 500 to 2000 bits per second, although some games used special, faster-loading routines, up to around 4000 bit/s. A rate of 2000 bit/s equates to a capacity of around 660 KB per side of a 90-minute tape.

Any type of Compact Cassette could be used, but smaller length cassettes such as C10 and C15 were produced for recording data.

Floppy disk storage become more prevelant by the mid-1980s, but cassettes remained popular for 8-bit computers such as the Commodore 64 and ZX Spectrum, particularly in the UK. Reliability of cassettes were variable, and multiple attempts to load programmes were sometimes required.

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