I believe that the statement that 3.5 inch floppy disks "are metric" refers to the standard that defines floppy disks. I don't know where to find the standard, but all the manufacturer's pages I can find all give the following for the case outer dimensions: 94 x 90 x 3.3 mm. None of them given any dimension in inches under the specifications.
It's not surprising that the actual disks be narrower than the nominal 90 mm. This sort of thing is common in engineering and manufacturing. For example, screws are almost always SHORTER than their nominal length, and holes are normally DEEPER than their nominal depth. It's just a way to make sure the parts fit together. Has anyone found / checked the actual governing standard? John On Monday 05 April 2004 11:28, Gavin Young wrote: > I don't understand why people say that a 3.5 inch floppy is not really 3.5 > inches. When I measure my floppy disks to the nearest 1/32 of an inch, the > dimentions are 3 1/2 in. by 3 5/8 inches. Thus one side is truly 3.5 > inches. Some prometric websites say that instead of 3.5 inches it is really > 90 mm, however my disks measure 89 mm x 93 mm. It is the opening to the > floppy drive bay that is 90 mm wide (the disk has to be slightly smaller or > else it won't slide into the drive)! Prometric people need to get the facts > straight if they are to be credible to nonmetric people.
