SPCR

I woke up from a nap today with a startling revelation. I will share it with you, free of charge.

The width of a 5.25" drive is 5.75".
The width of a 3.5" drive is 4".

The "drive size" refers to the width of FLOPPY DISKS - not drives!

2.5" drives are 2.75" wide. What does the 2.5" refer to? Good question, because to my knowledge 2.5" floppy disks never existed (2.0" disks did, see: http://en.wikipedia.org/wiki/Video_Floppy ). Perhaps the original 2.5" drives really were 2.5", but standardization resulted in a different size, while the 2.5" name stuck?

It was the size of the magnetic disk inside the floppy. You know, that black thing inside the plastic
http://scienceblogs.com/startswithabang ... y_disk.jpg

3.5" floppies are actually 90mm (3.54") wide. The disk itself is 85.8mm (3.38").

The inch-based nickname of all these form factors usually do not indicate any actual product dimension (which are specified in millimeters for more recent form factors), but just roughly indicate a size relative to disk diameters, in the interest of historic continuity.

http://en.wikipedia.org/wiki/Hard_disk_drive


Andy