The Physics
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Angular Speed of a Floppy Disk

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Cabanela, Juan. Physics 231 Problem Set #9 Solutions [pdf]. St. Cloud State University. 21 May 2005. "A 3.5-inch floppy disk in a computer rotates with a period of 2.00 × 10−1 s. What is. (a) the angular speed of the disk… ? (Note: A 3.5-inch floppy disk is 3.5 inches in diameter.) (Problem #10.10 on p. 301 of Walker)" 300 rpm
Floppy-Disk. 21 May 2005. "Floppies spin at 300 RPM, which is from 10 to 30 times slower than a hard disk." 300 rpm
D353GU USB External Type [pdf]. Chathay Group. 21 May 2005.
 1M Mode1.6M Mode2M Mode
Disk Rotational Speed (rpm)300360300
300–360 rpm
Floppy Disk Media Specifications. Disc Interchange Service Company. 21 May 2005. "All 8" disks have 77 cylinders recorded at 48 TPI (tracks per inch), and rotate at 360 RPM."
"5.25" Floppy Disks… Rotational speed is 300 RPM for the 300 Oe media and 360 RPM for the high density 600 Oe media."
3.5" Floppy Disks… Most drives rotate at 300 RPM, but some, Sony/HP in particular, rotate at 600 RPM."
300–360 rpm
Floppy Disk. Lockergnome Encyclopedia. 21 May 2005. "The drive maintained 300 rpm at all positions." 300 rpm

The first IBM machines to use semiconductor memory (the 370s) seemed quite an improvement from the older model, yet each time the power was turned off the microcode had to be reloaded. Therefore, in 1967, IBM challenged their San Jose, California storage development center to invent a simple and inexpensive system for loading microcode into their System/370 mainframes. The norm at the time was the tape drive, yet the tapes were large and slow. David Noble, working under the direction of Alan Shugart, decided to try something else. The upshot of their work was a read-only, 8 inch (20 cm) floppy they called the "memory disk," invented in 1971. Their "memory disk" held 80 kilobytes and rotated at 360 rpm. It was revolutionary for its time for its portability, which provided a new and easy physical means of transporting data from computer to computer.

The floppy, which acquired its name from its flexibility, is a circle of magnetic material similar to any kind of recording tape; one or two sides of the disk are used for recording. The disk drive grabs the floppy by its center and spins it like a record inside its housing. The read/write head, much like the head on a tape deck, contacts the surface through an opening in the plastic shell, or envelope. The Shugart floppy held 100 kilobytes of data. Over time, the disks became much smaller and were able to store more data. The next floppy that became quite popular was the 5.25 inch floppy, which spun at 300 rpm for the 300 Oe media and 360 rpm for the high density 600 Oe media. The 3.5 inch HD (high density) floppy was the last format to be ubiquitously adopted and had a storage capacity of 1440 KB and rotated at 300 rpm.

Floppy disks were universal in the 1980s-1990s, used on home and personal computer platforms to distribute software, transfer data, and create small backups. Before the popularization of the hard drive for PCs, floppies were also used commonly to store a computer's operating system, application software, and other data. However, floppies are now being replaced with new and improved forms of storage media such as CDs. They are becoming endangered and many computer manufacturing companies are now leaving floppy disk drives off their machines.

Genna Ableman -- 2005