When I insert any floppy into my pc, the capacity is 1.38, and not 1.44. I tried the floppies on XP Home, 98SE and on couple of Dells running on XP Pro at work. The same problem exists on every machine. I tried different brands of floppies and nothing, formating them does not do anything.

The funny thing is that when I had Win 95 and ME the capacity read of the same floppies read 1.44.

I heard that this is a common problem, but is there a way to fix this?

It is all a matter of how you calculate the capacity. Most consumers don't understand the binary system so manufacturers resort to a hybrid system of reporting the capacity and translates this into a decimal system consumers can understand. They base this on a kilobyte equals 1000 and not 1024.

So, following this logic you would have 2880*0.5 kilobytes/1000=1.44. This is all in marketing and rounding things off easily for the consumer to understand.

In acutality what we really have is this: 2847*512/1024=1423.5. Now the 1423.5 gets rounded down to 1423 and when you divide that by 1024 you get1.389648438 MB. The operating system then truncates this to 1.38.

I honestly don't remember how Win95 reported the capacity and I never used ME. I hope this helps.

But then why was I able to put files over 1.38 using ME onto the same floppies.
:confused:

Now win xp or 98 SE will now even read them.

You can store up to 1,457,664 bytes on a 1.38 "meg" floppy.

That is literally 1.457 MB (1.457664 x 10^6) if you use SI units of Decimal Notation.

Or, as explained, approx 1.38 MiB if you use "Computerese" based on a binary approximation.

This size of floppy is often (erroneously) referred to as a 1.44 MB diskette. These floppies do contain 2880 x 512 byte sectors and so could be called 1.44MiB floppies.

However the first 33 sectors (1 for the MBR, 18 for the FATs and 14 for the root directory) cannot hold data and so the data capacity falls from 1.44 to 1.38 MiB.

If you add up all the bytes (and not the kilobytes or megabytes) on such a floppy they cannot exceed 1,457,664 (which is ~1.38MiB).

Its a recurring problem of understanding "Prefixes for binary multiples" as per http://physics.nist.gov/cuu/Units/binary.html and very often MB gets written when the alternative MiB would be less open to misinterpretation.

This subject brings up another interesting point about formatting since I hardly use my floppy drive that much anymore and had almost forgotten.

Remember all of those Win95 installation disks? To achieve getting the most information on disks while using the fewest number of disks, MS developed DMF (Distribution Media Format) which allowed them to put 1.7MB of data on a 1.44MB disk. MS never fully documented this as far as I know for the general public.

When 1.44's were developed in the 80's, there was a wide range of differences between manufacturers of floppy drives in regard to the servo motors being used and there wasn't any real standards to control the variances from one manufacturer to the other. That's why the 1440K standard came along as a conservative response to disk-drive variances. Eighteen 512-byte sectors of data were defined for each of the 80 tracks on a 3.5-inch diskette. This allowed for a large gap between the sectors (the inter-sector gap) to accommodate speed variations between the various drive motors of different manufacturers.

Fast forward to the 90's and manufacturers developed more reliable drives and therefore more powerful and accurate speed controllers. This provided for more reliable data on a floppy. But at the same time you still have that large inter-sector gap, so programs were developed by others to take advantage of MS's technique. Basically, the DMF standard uses narrower gaps and then you can squeeze 21 sectors of data on each track instead of 18, so by using a narrower gap you are able to achieve a total capacity of 1680K.

One such program I have used in the past is SmartFormat. You could either format a disk as 1.44 or 1.72MB. It was always recommended that you use a "high-quality, name-brand" diskette to format to 1.72MB. It never seemed to me that I ever had the right diskette because every time I would format one I would end up having "bad sectors" recorded to the disk. Almost every time I would end up with a total of 1745408 bytes, 43008 bytes of Bad Sectors for a total of 1702400 bytes of Useable space. I quess that it didn't really matter that much since these sectors were at the end of the disk and fortunately not on Track 0 and 1, which would make it unuseable. Another program out there is WinImage and there are others. Some allow you to format at different capacaties and some are limited to only being used with a specific version of the Windows OS. I have found that most of them operate best if you run them at a DOS command prompt. The only exception to this of the ones I have tried would be WinImage which runs within Windows. WinImage is shareware and it has a 30-day trial. A lot of the others out there are free.

I had always been leary of Bad Sectors on a floppy disk from my DOS days and would often not use them. But using DMF sometimes solved problems of having a file just a little over 1.44 being able to fit by using DMF and so an occasional use of it didn't seem to matter.

Shortly after MS developed DMF, CD-ROM's became more prevalent and DMF wasn't much of a concern and sort of faded into the sunset. The technique is still there if you want to use it.

I'm not sure but I think Linux has always had the capability to format at different capacities and take advantage of DMF by using device commands. The Linux gurus should be able verify this since I don't use Linux although when I do finally upgrade, my old box will be a Linux machine.

As with any of these programs caution should be exercised and you should always use high-quality diskettes. You can format almost any old disk to DMF standards, but not all of them will retain the data for very long, and it becomes more important to store them somewhere safer than with your ordinary diskettes.