The origins of magnetic tape...

Recording on magnetic tape was developed in Germany during the second world war. One of its initial uses was the recording of music which was subsequently broadcast to the public via radio transmissions. At the end of the war the Allies were aware of these recorded broadcasts and made a great effort to uncover the magnetic tape data technology as they recognized its potential in all areas of recording.

These early recordings were achieved by the German technicians and scientists by coating a thin acetate sheet with iron oxide crystals suspended in a polymer binder. When passed over a magnetic recording head audio electrical signals in the head aligned the magnetic iron oxide partials. When the tape was subsequently passed over a similar play back head the aligned magnetic iron oxide partials educed a small electrical signal in the play back head which was amplified and reproduced the original audio signal. Various techniques were used to obtain the optimum output of reproduced sound. The most successful was to apply a high frequency signal above the audio range at the time of recording. This was call “bias” and is still used today for analog recordings.

During the late 40's and early 50's British and American scientists as well as the the original German scientists developed this technology which was used for audio analog recording, resulting in many applications including the initial recording of the sound track on 35 mm films as well as professional audio recording in 1/4” tape. The final sound track was converted to an optical system on the copy of the film released to the cinema.

By the mid 50's using saturating recording without bias it was found binary digital recording on magnetic tape was a viable solution as an alternative to punched paper tape and cards for the input and output of data from the early digital computers. This spawned the proliferation of many formats of digital recording. There was a clear need for a standard format which IBM pioneered. This was the 1/2” magnetic tape format which became the defector method of recording of input and output data using magnetic tapes. These early tapes are sill archived and Data Recovery Specialists Ltd. are regularly requested to recover the data from later generations of these tapes.