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The other day I accidentally stepped on one of my Zip
disks and broke the case. Since I broke it, I decided to open
it up and look inside. I was amazed to find that the disk
inside looks almost exactly like the disk inside a floppy
diskette. Why can a Zip disk store 250 megabytes when a floppy
disk can store only 1.44 megabytes?
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
#4,415,939: Head positioning servo for disk drive
#5,768,059: Head load/unload and cleaning in a data storage
#5,638,228: Retroreflective marker for data storage
#5,644,444: Read/write protect scheme for a disk cartridge
#5,677,818: Disk Cartridge with fuzzed liner
#5,237,477: Head wiper for Bernoulli disk drive
#5,530,607: Wing attachment for head load/unload in a data
#5,617,397: Movable internal platform for a disk drive
#5,650,891: Apparatus for performing multiple functions in a
data storage device using a single electro-mechanical device
Floppy Disk Drives Work
Hard Disks Work
Bits and Bytes Work
Computer Memory Works
Removable Storage Works
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