Bernoulli Box

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230 MB Bernoulli disk
20 MB Bernoulli disk

The Bernoulli Box (or simply Bernoulli, named after Daniel Bernoulli) is a high-capacity (for the time) removable floppy disk storage system that is Iomega's first widely known product. It was released in 1982.


The drive spins a PET film floppy disk at about 3000 rpm, 1 μm over a read-write head, using Bernoulli's principle to pull the flexible disk towards the head as long as the disk is spinning. In theory this makes the Bernoulli drive more reliable than a contemporary hard disk drive, since a head crash is impossible.

The original Bernoulli disks came in capacities of 5, 10, and 20 MB. They are roughly 21 cm by 27.5 cm, similar to the size of a sheet of A4 paper.

The most popular system was the Bernoulli Box II, whose disk cases are 13.6 cm wide, 14 cm long and 0.9 cm thick, somewhat resembling a 3 12-inch standard floppy disk but in 5 14-inch form factor. Bernoulli Box II disks came in the following capacities: 20 MB, 35 MB, 44 MB, 65 MB, 90 MB (late 1980s), 105 MB, 150 MB, and in 1993, 230 MB. There are five types of drives, grouped by the maximum readable capacity: 20 MB, 44 MB, 90 MB, 150 MB, and 230 MB. The interface is usually SCSI. Drives were available as either internal units, which fit into standard 5 14-inch drive bays, or as external units with one or two drives in a self-contained case connected to the host computer via external SCSI connector. The disks have a physical switch similar to that on 3 12-inch standard floppy disks to enable and disable write protection.


PC Magazine in 1984 stated that the Bernoulli Box "... combines the advantages of [standard] floppy- and hard-disk systems without their drawbacks." It reported no software-compatibility problems and cited the box's durable design.[1] Bruce Webster of BYTE wrote favorably of the peripheral in February 1986, reporting that "I have not had a single glitch or lost file" in nine months of constant use.[2]


Iomega's later removable-storage products such as the Zip floppy disk and Jaz and Rev removable hard disks do not use the Bernoulli technology.


  1. ^ Vaughan, Frank; Aarons, Richard (1984-09-18). "The Bernoulli Solution". PC Magazine. p. 148. Retrieved 25 October 2013.
  2. ^ Webster, Bruce (February 1986). "Programming Tool and the Atari ST". BYTE. p. 331. Retrieved 9 May 2015.

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