Floppy disk
From Mac Guides
A floppy disk, or simply floppy, is a data storage device used primarily in the 70's, 80's and 90's (although they are still used occasionally today, primarily with Windows computers). Apple was the first major computer manufacturer to stop including floppy drives with its computers, when it introduced the original iMac in 1998.
Floppies have been available in a number of sizes, although most people are familiar with the 3.5-inch variety (most of which had a capacity of 1.44 MB, although larger ones were developed). Before this, Apple used 5.25-inch floppies.
Floppy disks are named so not because the disk in itself is floppy - its casing makes it reasonably sturdy - but because the magnetic part of the disk which stores the data is floppy.
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Common Types
These are the most common types of floppy disks used in the Apple world as well as in varying PCs: ===5.25"===i The first floppy disks to be commonly used contained a 5.25-inch diameter flexible magnetic media with a 1-inch hole for the spindle. This disk was contained inside a square flexible plastic shell. This type was the predominant type of floppy used by the Apple II series, and later the IBM PC. It was essentially replaced by the 3.5" disk with the introduction of the Macintosh for Apple, and later in the PC world with IBM's PS/2. These large disks have a small index hole just outside the main spindle hole that the drive used to determine where the 'beginning' of the disk is. Apple DOS systems did not require this hole. These disks were marked as read-write by a notch cut out in the side of the disk at a certain location. They could be marked read-only by taping over that notch. (Pre-cut notches were standard in store-bought disks, whose packaging usually included pre-cut tape segments for marking the disk read-only. Commercial software disks tended to have no pre-cut notch, and if one wished to format the disk for other use, you had to cut the notch out by yourself. Likewise, when using a double-sided disk in a single-sided drive, a notch had to be cut for each side.)
- 'Low Density': 120 KB Single Sided, 240 KB Double Sided
- 'Double Density': 180 KB Single Sided, 360 KB Double Sided
- 'High Density': 1200 KB Double Sided only
Twiggy
- The 'Twiggy' was a 5.25" disk used by Apple in the original Lisa computer. It put the read/write for each disk side placed on opposite ends of the drive, and had a double sided capacity of 860 KB. (This was well before the introduction of the 'High Density' 1.2 MB 5.25" disk.) Its major downfall was reliability. Both the drives, and the disks, were prone to errors. This disk and drive was officially termed 'FileWare' by Apple, but it is much more commonly known as 'Twiggy'.
3.5"
The main type of floppy disk still reasonably common today contains a 3.5-inch diameter flexible magnetic media with a metal platter in the center with a small hole for the spindle, and a second for the track marker. This is contained inside a square hard plastic shell with a metal shutter to cover the hole for the read/write head. This made these disks much more tolerant of physical abuse than the older 5.25" disks. 3.5" disks are marked read-only by the use of a small shuttered hole on the top of the disk. A small plastic shutter could be slid to open the hole, marking the disk as read only, or blocking the hole, marking it as read-write. Commercial software often had no shutter, leaving the hole open constantly. This could be remedied by use of a piece of tape covering the hole.
- 'Double Density': 360 KB Single Sided, 720 KB Double Sided (Apple used a custom recording technique to format these disks at 400 KB or 800 KB. Apple-formatted disks cannot be read in standard PC drives. This technique involved speeding up or slowing down the speed at which the floppy spun in the drive, allowing more data to be placed onto it)
- 'High Density': 1440 KB Double Sided only
- 'Extended Density': 2880 KB Double Sided only(Introduced by NeXT in 1991, this type was common in IBM's high end computers for a few years, then largely abandoned.)
Floppy Alternatives
In recent years, there have been many alternatives to the floppy disk introduced. Some of the more common ones are:
- Zip Disk: A 3.5" disk (although not the same form factor as the 3.5" floppy) that contains 100 MB, 250 MB, or 750 MB of data.
- CD-R, CD-RW: A writable form of the CD-ROM format.
- USB flash drive: Sometimes called a 'thumb drive', or incorrectly referred to as a 'memory stick', these drives use flash memory and are available in many different capacities.;
Criticisms
During the 1990s floppy disks became more and more incapable of storing common files, due to the increasing size of most software. Much software was released on multiple floppies, which proved a hassle to use. Additionally, floppy disks were prone to corruption, much more so than more modern alternatives.

