Revision as of 10:41, 7 December 2006 view source Combuster (talk \| contribs) 1,490 edits m fixed spacing ← Older edit		Revision as of 23:42, 29 December 2006 view source osdev>Jhawthorn No edit summary Newer edit →
Line 1: File Allocation Table (FAT) was introduced with DOS v1.0 (and possibly CP/M), supposedly written by Bill Gates. FAT is a very simple filesystem which is nothing more than a singular linked list of clusters. FAT filesystems use very little memory and is one of, if not the, most basic filesystem in ~~existance~~existence today. == About FAT == Line 17: FAT32 was introduced to us by Windows95-B and Windows98. FAT32 solved some of FAT's problems. No more 64kb max clusters! FAT32, as its name suggests, can handle a maximum of 4gig clusters per partition. This enables very large hard disks to still maintain very small cluster sizes and thus reduce slack space between files. ~~''Correct -~~N.B. FAT32 is actually only FAT28. ~~Top~~The top 4 bits are, ~~currently "Undefined" (~~according to Microsoft's specification), "Undefined". ~~Note that this~~This does not mean 'that the top four bits should be "0"~~' - they should be honored~~. ~~This means that if you need to alter~~When a FAT entry, ~~and~~is altered the top 4 bits ~~contain 1001, you~~ should ~~write~~be itleft ~~back to disk containing 1001 and not 0000~~unchanged.~~'' -- djhayman~~▼ ''Is FAT32 really able to handle 4G clusters ? last time i looked to a FAT table, it looked to have last 4 bits cleared all the time, including the 'end of chain' tag, giving me the feeling that it was somehow more a "FAT28" than "FAT32"'' -- PypeClicker ▲''Correct - FAT32 is actually only FAT28. Top 4 bits are currently "Undefined" (according to Microsoft's specification). Note that this does not mean 'top four bits should be "0"' - they should be honored. This means that if you need to alter a FAT entry, and the top 4 bits contain 1001, you should write it back to disk containing 1001 and not 0000.'' -- djhayman == Implementation Details == Line 364 ⟶ 362: (8- 2) sectors * 512 Bytes per sector = 3072 Bytes (decimal) C00 Bytes + 4200 Bytes = 4E00 Entry value of seventh cluster is 4E00. ==See ~~Links~~ Also== === External Links === * http://scottie.20m.com/fat.htm * from raw bits to directory listing (code posted) in the [[Topic:11247\|forum]]

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