Floppy disk

Alternatively referred to as a floppy or floppy disk, a floppy diskette was originally created in 1967 by IBM to help have an alternative to buying hard drives that were extremely expensive at the time and were not thought of as something to be used with a standard computer. Below is a brief history of each of three major floppy diskettes. Today, these disks have been replaced by writable discs and USB thumb drives.

8" Disk

The first disk was introduced in 1971. The disk was 8" in diameter with a magnetic coating, enclosed in a cardboard case with the capacity of one megabyte. Conversely to hard drives, the heads touched the disk, like in a cassette or video player that wears the media down over time.

5.25" Disk

First started development in 1976 and later became a standard in 1978, these disks were first released with only 160KB of disk space. These diskettes were commonly used in 1980's and began stop being used in the early 1990's.

5.25" Single Side - 160KB
5.25" Double Side - 360KB
5.25" Double Side High Density - 1.2MB

5 1/4" floppy diskette5 1/4" floppy disk diagram

The 5 1/4" floppy diskette was really floppy (flimsy), hence the name. As you can see in the above illustration, the 5 1/4" floppy does not have many involved components. First, you will notice the write protection tab that would be found on diskettes that allowed information to be written to them. To write-protect the diskette, a piece of tape is placed over the hole, or if there is no hole the diskette is already write-protected.

Second, notice the large hole in the center of the floppy diskette. This hole allowed the platter within the floppy to be rotated allowing the information to be read from the read/write access hole.

Third, notice the index hole, this hole was the computer's way of knowing where the starting point of the sector was on the diskette by physically having a hole punched in the film disc within the plastic casing.

Finally, the write access hole is where the computer floppy drive would write the information to the diskette.

3.5" Disk

Created by IBM in 1984, these diskettes were first introduced with a total capacity of 720KB. The 1.44MB floppy diskettes were used widely in the 1990's and were seldom found or used by 2000.

3.5" Double Density - 720KB
3.5" High Density - 1.44MB (Why it's 1.44MB)
3.5" Extended Density (IBM ONLY) - 2.88MB

Below is a graphic of a 3.5" floppy diskette. As can be seen by the picture below, this particular diskette is clear, which enables you to see inside of the diskette. You can notice that the floppy has a circular cloth that is located on both sides of the floppy; this cloth helps clean and protect the magnetic disk within the diskette.

Clear 3.5" floppy diskette

3.5" floppy diskette diagram

In the above diagram, notice the small write protect tab. This tab enables the floppy disk to be switched from write-protected and unwrite-protected. Move the tab to the top position, creating a hole, makes the disk write protected. This means that nothing can be written or deleted from the diskette. Moving the tab to the bottom position allows the disk to be un-write protected, which means the diskette can be written too, erased, or have information deleted from the diskette. Some diskettes, which are cheaper diskettes, will be missing this tab. To write information to the diskette you have to place a piece of scotch tape over the hole.

Second, the top-right hand of the back of the floppy you will notice a small hole. This tells the computer if the diskette within the computer is a High Density diskette.

Third, the circular metal disk in the middle of the floppy diskette. This is used to rotate the magnetic medium within the floppy disk casing.

Finally, there is a metal door that can be moved left and then will snap back to its original position. This door is used to allow the read/write head within the floppy drive to have the capability of accessing the magnetic medium within the casing. Once the diskette is removed, this door will snap back into position, helping to prevent anything from getting on the magnetic medium and destroying it. This also makes these types of diskettes more reliable than the earlier 5.25" diskettes.

Related pages

Also see: Floppy cable, Floppy drive terms, Floppy disk drive