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Floppy Disks and Drives

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Computer Maintenance

History of the Floppy Disk Drive The floppy disk drive (FDD) was invented at

IBM by Alan Shugart in 1967. The first floppy drives used a 12-inch, and then an 8-inch disk (later called a “diskette” as it got smaller), which evolved into the 5.25-inch disk that was used on the first IBM Personal Computer in August 1981. The 5.25-inch disk held 360 kilobytes, compared to the 1.44 megabyte capacity of today's 3.5-inch diskette.

The 5.25-inch disks were dubbed “floppy” because the diskette packaging was a very flexible plastic envelope, unlike the rigid case used to hold today's 3.5-inch diskettes.


History of the Floppy Disk Drive

By the mid-1980s, the improved designs of the read/write heads, along with improvements in the magnetic recording media, led to the less-flexible 3.5-inch, 1.44-megabyte (MB) capacity FDD in use today. For a few years, computers had both FDD sizes (3.5-inch and 5.25-inch). But by the mid-1990s, the 5.25-inch version had fallen out of popularity, partly because the diskette's recording surface could easily become contaminated by fingerprints through the open access area.


History of the Floppy Disk Drive


The invention of hard disks relegated floppy disks to the secondary roles of data transfer and software installation. The invention of the CD-ROM and the Internet, combined with the increasingly large size of software files, is threatening even these secondary roles. The floppy disk still persists, basically unchanged for over a decade, in large part because of its universality; the 3.5-inch, 1.44 MB floppy is present on virtually every PC made in the last 10 years, which makes it still a useful tool.

Note: In 2004 all the major manufacturers started shipping all new systems without floppies. They are still available as an add-on item.

Disk Size

The original disks were 12" in diameter and could be damaged easily.

IBM came out with 8" disks that had protective shells on them.

5-¼" disks were an improvement in the design.

The newest floppy disks are 3-½" and have a hard shell.


Floppy Capacity Designations (5-¼"):

DS:DD – Double-Sided, Double-Density (360KB)

DS:HD – Double-Sided, High-Density (1.2MB) Designations (3-½")

DS:DD – Double-Sided, Double-Density (720KB)

DS:HD – Double-Sided, High-Density (1.44MB)

DS:EHD – Double-Sided, Extra High-Density (2.88MB)


Floppy Drive Connections

All floppy drive cables allow you to connect 2 drives to each system.

Designated by A: and B: The position on the cable determines

whether it is A: or B: The drive type is set in CMOS. Always connect pin 1 on the cable to pin 1

on the drive.


Cable Positions


Uses a Ribbon Type cable with 34 pins.

All drives after the twist are A: (#3).

Drives in the middle are B: (#2).

The end plugs into the motherboard (#1).

Power Connectors

5-¼" drives use a Molex connector.

3-½" drives use a Berg connector.

Can be inserted one way only


Floppy Drive Basics


The floppy disk’s current role is in these areas:

Data Transfer: The floppy disk is still the most universal means of transferring files from one PC to another. With the use of compression utilities, even moderate-sized files can be shoehorned onto a floppy disk, and anyone can send anyone a disk and feel quite confident that the PC at the other end will be able to read it. The 3.5" floppy is such a standard, in fact, that many Apple and even UNIX machines can read them, making these disks useful for cross-platform transfer.

Floppy Drive Basics



Small File Storage and Backup: The floppy disk is still used for storing and backing up small amounts of data, probably more than you realize.

Floppy Drive Basics



Software Installation and Driver Updates: Many new pieces of hardware still use floppies for distributing driver software and the like. While floppy drives still have a useful role in the modern PC, there is no denying their reduced importance. Very little attention is paid to floppy “performance” any more, and even choosing makes or models involves a small fraction of the amount of care and attention required for selecting other components.

Parts of a Floppy Disk DriveA floppy disk is made from a thin piece of plastic coated with a magnetic material on both sides. The tracks are arranged in concentric rings so that the software can jump from “file 1” to “file 19” without having to fast forward through files 2-18. The diskette spins like a record and the heads move to the correct track, providing what is known as direct access storage.


In the illustration above, you can see how the disk is divided into tracks (brown) and sectors (yellow).

Parts of a Floppy Disk Drive Read/Write Heads: located on both sides of a

diskette, they move together on the same assembly. The heads are not directly opposite each other, in an effort to prevent interaction between write operations on each of the two media surfaces. The same head is used for reading and writing, while a second, wider head is used for erasing a track just prior to it being written. This allows the data to be written on a wider “clean slate,” without interfering with the analog data on an adjacent track.

Drive Motor: A very small spindle motor engages the metal hub at the center of the diskette, spinning it at either 300 or 360 rotations per minute (RPM).


Parts of a Floppy Disk Drive

Head Actuator: the device that physically positions the read/write heads over the correct track on the surface of the disk. Floppy disks generally contain 80 tracks per side. The actuator is driven by a stepper motor.

Stepper Motor: this motor makes a precise number of stepped revolutions to move the read/write head assembly to the proper track position. The read/write head assembly is fastened to the stepper motor shaft.


Parts of a Floppy Disk Drive

Mechanical Frame: a system of levers that opens the little protective window on the diskette to allow the read/write heads to touch the dual-sided diskette media. An external button allows the diskette to be ejected, at which point the spring-loaded protective window on the diskette closes.

Circuit Board: contains all of the electronics to handle the data read from or written to the diskette. It also controls the stepper-motor control circuits used to move the read/write heads to each track, as well as the movement of the read/write heads toward the diskette surface.


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