next up previous contents
Next: NTFS Up: FAT Previous: Cluster Sizes

Directory Entries

In the original FAT file system used by MS-DOS and Windows prior to Windows 95, a directory entry consists of 32 bytes of information, as shown in Figure 5.1. [Kin94]

FAT Directory Entry

Figure: A FAT file system directory entry [Kin94]

While filenames on a FAT file system consist of eight characters plus a three character extension, the VFAT file system used by Windows 95 supports up to 259 characters. The additional characters are stored in additional 32 byte directory entries. In addition, two bytes are used for each character of the filename. A VFAT directory entry is shown in Figure 5.2. [Kin94]

VFAT Directory Entry

Figure: A VFAT file system directory entry [Kin94]

In order to load your files, the file system has to locate the correct directory entry on the disk. FAT starts at the top of the list and reads through the entries one at a time until the desired file is located. [Pro95]

Barnett Hsu