The 1.44-megabyte floppy disk drives that use 3.5-inch diskettes have been around for about 15 years. At the time of their introduction, they seemed like a miracle -- they were smaller than the standard 5.25-inch disks, but they held more data!
Here are some of the parameters that determine how much data a floppy disk can hold:
Two important things to notice are the low number of tracks on the disk and the fixed number of sectors per track. Neither one of these techniques makes very good use of the surface of the disk.
The main thing that separates a Zip disk from a floppy disk is the magnetic coating used on the disk. On a Zip disk, the coating is much higher quality (see How Tape Recorders Work for some discussion on magnetic coatings). The higher quality coating means that a Zip disk read/write head can be significantly smaller than a floppy disk's (by a factor of 10 or so). The smaller head, combined with a head positioning mechanism similar to that used in a hard disk, means that a Zip drive can pack thousands of tracks per inch on the track surface. Zip drives also use a variable number of sectors per track to make the best use of disk space. All of these things combine to create a floppy disk that holds a huge amount of data!
These links will help you learn more:
- Iomega Zip Drives
- Patent #4,415,939: Head positioning servo for disk drive
- Patent #5,768,059: Head load/unload and cleaning in a data storage device
- Patent #5,638,228: Retroreflective marker for data storage cartridge
- Patent #5,644,444: Read/write protect scheme for a disk cartridge and drive
- Patent #5,677,818: Disk Cartridge with fuzzed liner
- Patent #5,237,477: Head wiper for Bernoulli disk drive
- Patent #5,530,607: Wing attachment for head load/unload in a data storage device
- Patent #5,617,397: Movable internal platform for a disk drive
- Patent #5,650,891: Apparatus for performing multiple functions in a data storage device using a single electro-mechanical device
- How Floppy Disk Drives Work
- How Hard Disks Work
- How Bits and Bytes Work
- How Computer Memory Works
- How Removable Storage Works