> What's the difference, if any between the two different FAT formats?
Not much. They're both disk-space allocation schemes used in computer file systems for Microsoft PC operating systems. FAT actually stands for File Allocation Table. The main difference is that FAT16, the old FAT, was invented 20-25 years ago when operating system software engineers didn't have a good idea of how big and cheap the hard drives in PC's were going to get, and the computers they worked with were a lot slower. So they designed the original FAT to accommodate hard drives up to a size they then considered reasonable, 2 Gigabytes, which at that time was larger than anything they could imagine (software engineers are sort of dumb, though they are totally convinced of the contrary). That 2GB limitation stems mostly from the choice of a 16-bit number to hold the maximum number of "clusters" of disk blocks that reside on any single FAT-organized disk drive. Since 65,536 is the largest 16-bit number, under the older FAT16 file system, that's the largest total number of "clusters" that any file system can have in the aggregate of all its files (in the case of your flash card, that's the number of 512-byte memory units that can be allocated to all the images on the card). What's a "cluster"? That's the unit of disk space that can be allocated to a file at any one time, and it's expressed as a number of 512-byte disk sectors. 512 bytes is arbitrary for a flash card but wasn't arbitrary for a disk drive. (Not sure but probably not arbitrary for a microdrive.) FAT clusters can vary in size. The smallest a cluster can be is 1 disk sector, or 512 bytes, and the largest it can be (under the old FAT) is 64 disk sectors, or 32,768 bytes. When you multiply all those together, the biggest possible FAT file system consists of 65,636*64*512=2,147,483,658 bytes, or 2 Gigabytes, of storage space. Keep in mind that when FAT was invented for 20-year-old personal computers, one spreadsheet or word-processing document was way smaller than one little jpeg image from a mid-range digital camera is today. FAT16 and DSLR's weren't meant for each other. Companies just used FAT as the digital camera standard because it was free, simple, and well-exercised after 20 years of 24/7 global use. The FAT32 variant is a minor redesign of the FAT system that Microsoft did in the mid-80's after they realized that hard drives were going to grow without bounds, and rapidly outgrow the old FAT. The reason it's called FAT32 is that a 32-bit number, the largest of which is 4 billion and something, became the maximum number of clusters in a file, and the clusters got bigger too. FAT32 is still used a lot in computers running older versions of Windows; its virtue is that it can now handle large amounts of disk space but it's still simple. In newer versions of Windows, like 2000 and XP, more grown-up computer-science file systems like NTFS are used by default, although the FAT systems are still supported. (Same general story applies in the Macintosh world.) FAT32 can organize storages space smaller than 2GB with no problem--it just uses up a tiny bit more housekeeping space for its tables that becomes unavailable to images. However the older FAT16 *CANNOT* organize spaces larger than 2GB for the reasons outlined above. > Should I format my 1GB compact flash card to FAT32? > You should just let your camera format the card, and it will format it to whatever it's comfortable with. Let the camera decide--you don't need to. Just don't try to format a card bigger than 2GB with old FAT. When in doubt, use FAT32, but in general you won't ever be in doubt if you just let the camera decide for you. Early digicams, including some DSLR's like the D30, don't know about FAT32, they only know old FAT. (This was basically the camera manufacturers repeating the software engineers' 1982 error, for the same reason: smaller flash cards and slower microprocessors in the cameras). With those cameras, you could either avoid storage cards larger than 2GB (why put a 4GB microdrive in a D30?) or, better still, replace the camera with a good one. --Ken S. * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
