##### FAT Time

The time values in a FAT file system can be found in the directory ('folder' in modern terminology) entries. The times recorded on disk are in LOCAL time (i.e. the appropriate time zone and DST setting has been applied).

1980 is the default year for FAT dates which means that the epoch date for this particular time encoding is therefore 1980-01-01 00:00:00.00

The largest FAT date is 2107-12-31 23:59:59.99

When recorded on disk FAT times take a number of different formats. These formats have one or more of the following constituents:

- Date (2 byte number)
- Time (2 byte number)
- Milliseconds (1 byte number)

The 'created' date in FAT takes the form of Milliseconds followed by Time followed by the Date part and so is a 5 byte entity. This has a granularity of 10ms.

The 'modified' date takes the form of the Time part followed by the Date part and is therefore a 4 byte entity. This has a granularity of 2s.

The 'accessed' date in FAT is just the Date part and is therefore just a 2 byte entity. This has a granularity of 24hrs

Because DOS and Windows were only ever intended for Intel (and compatible) processors the numbers comprising each constituent part are recorded on disk in little endian format. For example a created time would appear on disk thus:

--------------------------------------------------------

| ms | time component | date component |

--------------------------------------------------------

| ms | time LSB | time MSB | date LSB | date MSB |

--------------------------------------------------------

| byte 1 | byte 2 | byte 3 | byte 4 | byte 5 |

--------------------------------------------------------

(MSB = most significant byte, LSB = least significant byte)

FAT times can be found in locations other than the FAT files system. For example, some Internet Explorer URL records (found in index.dat files) have FAT dates but the sequence on disk is different to that shown here, in this case the date component is first (bytes 1 and 2) and the time component comes afterwards (bytes 3 and 4).

##### FAT Time Resources

- Wikipedia Entry