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  From the September 2008 Issue of Prestwood eMag
 
Removable Storage Technology:
Removable Disks - a brief overview & history
 
Posted 10/8/2007 on 10/8/2007 and updated 9/3/2008
Take Away: Wherever would we be without portable, inexpensive removable media? From the old, eight-inch floppy, to the latest Blue Ray DVD format, little spinning disks have provided computer users with convient, off-line storage. This is a brief overview and history of the various disk formats that have come, gone, and are - for the moment - sticking around.

KB100696

The table, below, is not exhaustive. It's limited to those disk formats that were/are important to personal computer users.

Name (somewhat generic) Size A little history
Floppy 8" It all started here: In 1969, an IBM Product Manager named Alan Shugart was tasked with creating an inexpensive and convenient removable storage format faster than the then common tape drives. The result was an 8-inch flexible plastic envelope containing a magnetic disk. It was a  read-only proposition with a whopping 80 Kb capacity.

Shugart left IBM for Memorex, and, in 1972 Memorex released their 650 disk, a hard-sectored, 175 Kb read/write disk similarly packaged. In 1973,  IBM followed with a 250 Kb,  soft sectored disk of similar design.

Also in 1973, Shugart founded his own company and they produced an 800 Kb disk.  These became a sort of microcomputer industry standard for a while.  I well remember getting my first 8-inch floppy drive.  I paid $175 for it - used - and thought I was in pig heaven, having lived with cassette tape as the storage media for my home-brewed S-100 machine.

Burroughs Corp, meanwhile, developed a dual sided 8" with 1G capacity.
Minifloppy 5-1/4" Around 1976, various smaller  incarnations (around 5 inches) of the floppy began to appear,  beginning with 90 Kb (hard sector) and 110 Kb (soft sector). Initially single-sided, people used to cut  a second write-enable slot and index hole on the other side of the plastic housing so they could flip the disk  over to get double the storage. In 1978 Tandon introduced a double-sided disk,  drive, and double density format: 360 Kb. In 1984, with the  introduction of the IBM PC/AT, 1,200 Kb was attained.

I well remember getting repeated calls from the secretary at one of my client's offices.  She'd carefully save her word processing files, but the next time she tried the disk, her files were gone.  I investigated everything I could think of, but could find nothing wrong with her machine, her software, or her box of fresh disks.

One day I arrived unexpectedly and spotted the problem: She was affixing her floppy disks to a file cabinet with refrigerator magnets!  I've heard the same story from one tech after another.
Floppy 3-1/2" HD The 8-inch and 5-1/4 inch floppy drivers were mechanically complex, relatively expensive  - and could be unfriendly to careless users.  Further, the "floppiness" of the disks exposed them to physical damage in the hands of the ham-fisted.

As early as 1973, various companies were experimenting with hard plastic cased disks,  in various sizes hovering around 3 inches square.  A plethora of different types and formats appeared.  The one that "won" ubiquity was 1.44 Kb, 3-1/2, HD (high density)  standardized in 1989.

Although virtually obsolete today, it lives on as the "Save" button image on virtually every program's toolbar that you see.
Zip Drive/Disks About 3-1/2" Even an abbreviated history of removable media would be incomplete without mentioning these abominations from Iomega, introduced in 1994. Capacity started at 100 Mb, then went to 250 and 750 Mb.  They held great promise for large capacity and convenience.  Those factors, coupled with aggressive promotion made the things fairly popular.

They may have started out as a good product.  I don't really know.  But about the time they were gaining critical mass, incredible numbers of these gadgets failed with the now infamous "click of death," a telling noise that predicted imminent failure - if failure hadn't already happened - and led to a class action lawsuit against Iomega.
Jazz Drive About 4" Another Iomega product, the Jazz Drive had much greater capacity than the Zip Drive, starting out at 1 and 2 Gb - and promised to be quite a bit faster - nearly as fast as a "real" hard drive.  I bought one. I found the device and media (essentially a two-platter removable hard drive) to be expensive - and unreliable. One of the worse purchases I've ever made.
CD-ROM, CD-R, CD-RW 12 CM All of the above used magnetic media - and suffer from its vulnerabilities to nearby magnetic fields - and age. Optical storage is a revolutionary leap forward, first popularized by music on CD.  Today, it's virtually impossible to purchase a new machine without an optical reader/burner.

Typical disk capacities are 650MB & 700MB - with 800 & 900 around.
Mini CD 8 CM Designed to be played - or burned - in ordinary CD players, these have a capacity of 23.4 Mb.  They're frequently used to provide device drivers for a variety of computing peripherals, like Bluetooth adapters, etc. If you have something to distribute - and it will fit, these can be pretty cool.
DVD 12 CM Available as read-only (like the movies you rent), read/write, and rewriteable - pretty much like CDs - DVD optical disks offer even greater capacity. Single layer 4.7G, dual layer: 8.5 G
HD DVD 12 CM The march toward denser and denser data storage marches on.  HD DVD offers 15 G in single layer,  30 G in dual layer.

Beware before taking the leap into this next generation of optical storage.  Unlike the situation with CD and DVD, this new DVD format has not yet claimed the throne.  There's an industry battle between HD DVD and Blue Ray  DVD, below.

It's much like the old rivalry between Sony's Beta video tape format and VHS:  The best technology is not guaranteed to win.
Blue Ray 12 CM Using a blue-colored laser, rather than the more common red laser to burn the data, Blue Ray discs attain 25 G in single layer, 50 G in dual layer.

What's the difference between DVD, HD-DVD, and Blue Ray? This is a brief overview and history of the various disk formats that have come, gone, and are - for the moment - sticking around.

  • Blue Ray 
  • HD DVD 
  • DVD 
  • Mini CD 
  • CD-ROM, CD-R, CD-RW 
  • Jazz Drive 
  • Zip Drive/Disks 
  • Floppy 
  • MiniFloppy 
  • 8" Floppy

A historical overview of removable storage devices, including dates of introduction, pertinent information, and capacities.

KB Post Contributed By Wes Peterson:

Wes Peterson is a Senior Programmer Analyst with Prestwood IT Solutions where he develops custom Windows software and custom websites using .Net and Delphi. When Wes is not coding for clients, he participates in this online community. Prior to his 10-year love-affair with Delphi, he worked with several other tools and databases. Currently he specializes in VS.Net using C# and VB.Net. To Wes, the .NET revolution is as exciting as the birth of Delphi.

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Printed 9/24/2020