Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928 and was widely used throughout the 20th century for audio and analog data recording. Though less commonly used since the introduction of digital storage in the 1970s and 1980s, magnetic tape remains an important storage medium for backup and archival use.
Early examples of magnetic tape
The earliest magnetic tape recording devices were developed in the 1920s and 1930s. These included:
- The Blattnerphone, invented in 1928, which recorded audio signals on steel tape
- The magnetophon, developed in 1930s Germany, which used plastic tape coated with iron oxide powder
- The German BASF’s first magnetic tape recording devices in 1935
- AC biasing, invented by Fritz Pfleumer in 1936, which dramatically improved sound quality
- The Interrecord wire recorder, developed in 1942, an early dictation machine using steel wire
These early tape recorders were used for dictation, telephone recording, radio broadcast, and a variety of sound recording applications. They recorded analog signals on tape widths ranging from 1/4″ to 1″ and tape speeds from 30 to 100 ips.
Audiophile reel-to-reel tape
In the 1950s and 1960s, higher fidelity open reel tape recorders emerged for audiophile and professional use. These included:
- Ampex’s line of professional studio recorders like the Ampex 300 from 1948
- The Ampex Model 200 home audiophile recorder from 1948
- Higher fidelity recorders from companies like Ferrograph, Tandberg, Uher, and Studer
- Multitrack recorders like Ampex’s 8-track from 1957
- Analog tape formats like 7″ reels at 15 ips and 1/4″ tape on 10.5″ reels at 15 or 30 ips
These reel-to-reel recorders offered extended frequency response up to 20 kHz and low noise operation. They were used heavily in recording studios and radio stations and by audiophiles for home recording.
Compact cassette tape
In 1963, Phillips introduced the compact audio cassette tape format. Key features included:
- Small size plastic case containing two miniature open tape reels
- 1/8″ width tape running at 1 7/8 ips
- Stereo or mono recording on quality formulations like chrome and metal tape
- Portable, convenient operation
This compact cassette gained immense popularity for portable audio applications. Cassette recorders were widely used with portable stereos and boomboxes. Various formulations extended frequency response and lowered noise.
8-track tape
In 1964, Bill Lear’s 8-track tape format was introduced for automobile audio. It consisted of:
- 1/4″ magnetic tape configured in a compact cartridge
- Eight separate parallel tracks allowing continuous play
- Four programs with stereo sound per cartridge
- Tape speed of 3 3/4 ips
8-track tapes provided a convenient format for audio players in cars. Their sound quality eventually improved, but couldn’t match audiophile open reel recorders.
Digital audio tape
In 1987, Sony and Phillips introduced the digital audio tape (DAT) recorder using a new 4mm tape cassette. Key features included:
- Rotating helical scan heads like a video recorder
- Pulse-code modulation digital recording
- Extended frequency response and dynamic range
- Excellent fidelity exceeding compact discs
Though popular for professional use, DAT failed to gain traction in consumer markets due to record industry opposition, leading to its discontinuation in 2005.
VHS and Betamax videotape
Magnetic tape was also pivotal for video recording, used in formats like:
- VHS – Released in 1976, using 1/2″ wide tape in cassettes capable of up to 8 hours of recording.
- Betamax – Released in 1975, using 1/2″ tape with slightly higher quality than VHS.
- Video8 – Using 8mm tape in cassettes, released in 1985.
- Hi8 – An upgraded higher resolution 8mm format from 1988.
Of these, VHS gained widespread adoption and dominated the home video market in the 1980s and 1990s.
Backup and data tape
Magnetic tape found widespread use for bulk data storage and backup applications:
- 9-track tape – Used for mainframe computer data backup beginning in the 1960s.
- IBM 3480 cartridges – For data storage from the mid 1980s.
- DLT and LTO tape – Higher capacity single reel data cartridges introduced from the 80s to 2000s.
- IBM 3592 – For enterprise-level storage, introduced in 2003.
Tape offers advantages like long-term durability, high capacity, and low cost for infrequent access archive data. Backup tape sales have declined recently but tape is still used extensively by large organizations.
Floppy disk magnetic recording tape
Floppy disks used flexible magnetic tape disks in protective plastic cases for data storage and transfer:
- 8-inch floppies – Introduced by IBM in 1971, storing up to 500 kB.
- 5.25-inch floppies – The mini floppy, introduced in 1976, storing up to 1.2 MB.
- 3.5-inch floppies – Introduced in the 1980s, storing up to 2.88 MB.
Floppy disks became a ubiquitous medium for data storage and transfer in computing from the 1970s to 1990s. But hard drive and USB flash drives have now completely displaced floppies.
Other tape applications
Some other uses of magnetic tape include:
- Analog instrumentation recording in science and medicine
- Tape-based computer storage like UNISERVO from 1951
- Early computer numerical control systems
- Cash register and calculator recording tapes
- Magnetic stripe cards like credit cards and public transit cards
So magnetic tape has served a variety of audio, video, data storage and recording applications from the 1930s to the present day.
Notable tape types summary
Here is a table summarizing some noteworthy magnetic tape types:
| Tape Type | Key Features and Uses |
|---|---|
| Reel-to-reel audiotape | – Open reels of 1/4″ or wider tape – For studio recording and audiophiles – Fame from 1930s to 1970s |
| Compact cassette | – Enclosed tape reels in plastic case – Portable consumer audio since 1963 |
| 8-track | – Tape in self-contained cartridges – For car audio from mid 1960s into 1980s |
| Digital audio tape | – Digitally encoded high fidelity – 4mm cassettes introduced 1987 |
| VHS and Betamax | – 1/2″ tape in cassettes – Home video recording from late 1970s |
| Computer backup tape | – For enterprise data backup since 1960s – Increasing capacities and longevity |
| Floppy disk | – Magnetic tape disks in plastic cases – Ubiquitous from 1970s to 1990s |
Conclusion
Magnetic tape has served as an indispensable storage medium throughout the electronics age. Beginning in audio recording, it expanded to video, data storage, and mass-market formats like cassettes and floppies. Though it has declined in some areas, tape remains irreplaceable for backup and archiving applications. Tape’s legacy will live on as long as we need to store data.