(3 1/2 inch or 90mm floppy). Floppy diskette, very popular in the 1990s, used for data storage. They are 8.9 cm x 9.3 cm in size and eventually replaced 5 1/4-inch floppy disks.
The most popular floppy disks come in two densities: the low-density ones hold 720KB, while the high-density ones hold 1.44MB.
They are now considered obsolete and have been replaced by optical disks and flash drives.
Other names used in the past: Micro diskette, Micro disk, Micro floppy, 3-inch floppy disk.
For more information read: floppy.
History and Characteristics of the 3½ Inch Floppy Disks
In the early 1980s, several manufacturers released drives for small floppy disks in various formats. Eventually, a consortium that brought together 21 companies in the industry agreed to create the standard size of 3 inches (90 mm wide) for these diskettes, also known as Micro diskette, Micro disk or Micro floppy.
At that time there were two versions: 360 KB (released in 1983 and single-sided) and 720 KB (released in 1984 and double-sided). Then in 1986 the most popular format was released, High Density Duplex (HD) with a capacity of 1.44 MB.
While in Macintosh computers, single-sided 3-inch floppy disks with 400 KB capacity were used. Then in 1986 the double-sided 800 KB was released. Later Macs were able to read and write PC-format 1.44 MB HD disks.
All 3-inch floppy disks had a rectangular hole in one corner which, if closed, allows the disk to be written to (number 1 in the image).
Those 1.44MB HD drives have a second hole, which simply indicates that it is a drive of that capacity (it cannot be closed).
On IBM-compatible PC computers, all three densities of 3-inch floppy disks are backwards compatible: high-density drives can read, write, and format low-density media.
It is possible to format a drive to the wrong density, resulting in a drive that does not work properly.
1. Write protect notch, 2. Center base, 3. Movable cover, 4. Plastic chassis, 5. Paper ring, 6. Magnetic disk, 7. Disk sector
Special 3-inch high-capacity discs
Special high-capacity 3-inch disks were launched, but with less acceptance, due to the arrival of optical disks and later flash memories:
– 3-inch ED, released in 1987, with a capacity of 2.88 MB
– 3-inch Floptical (LS), released in 1991, with a capacity of 21 MB
– 3-inch Superdisk (LS-120), released in 1996, with a capacity of 120 MB
– 3-inch Superdisk (LS-240), released in 1997, with a capacity of 240 MB
– 3-inch HiFD, released in 1998 and 1999, with capacities of 150 MB and 200 MB.
Related:
How to install a floppy drive
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