Magnetic tape was first invented for recording sound by Fritz Pfleumer in 1926 in Germany, based on the invention of magnetic wire recording by Valdemar Poulsen in 1898. A wide variety of recorders and formats have developed since. Magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I.

Magnetic tapes were made of a plastic or metal surface, with a thin electromagnetic layer that can be polarised and thus record binary data. Characters of information are recorded sequentially and can be written in different densities. The most used densities were 200, 556, 800 and 1600 characters per inch (79, 220, 315, 640 characters per centimeter) of tape.

Data was written in blocks. The characters in a block are written one after another without a pause. Blocks are separated by 19mm spaces of empty tape, to reduce the possibility of errors. Characters written to the tape comprise either of 6 or 8bit, with the addition of another bit reserved for error checking. So there are two types of tape, one with 7 tracks and the other with 9 tracks.

When data is read from or written to the tape, it unwinds from its reel and winds on the auxiliary reel, passing by the writing and reading heads. The breaking mechanism stops the tape as needed. From the main reel, the tape goes into a vacuum column, where photoelectric indicators ensure the right ammount of tape in the column. Dependent on the rotation direction, pressure or negative pressure is made in the perforated driving rollers. On the picture (left) is clearly visible the pneumatic principle of reading / writing data to the tape.

In the museum you can see:

• Graham Magnetics Ultimag introduced in 1980 and
• 3M SCOTCH 777gp tape, year 1968