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 1⁄2-inch standard floppy disk but in 5 1⁄4-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 1⁄4-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 1⁄2-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. 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.