Technical information
© Jean Louis-Guérin – V1.2a – September 2014 Page 61 / 69
Here a Practical example of a disk with only 4
entries:
Dump of the directory table:
Offset 0 1 2 3 4 5 6 7 8 9 A B C D E F
0002A000 53 48 4F 52 54 20 20 20 54 58 54 20 00 0F 9B 81 SHORT TXT ..›•
0002A010 8D 3B 8D 3B 00 00 A0 8C 8C 3B 02 00 0E 00 00 00 •;•;.. ŒŒ;......
0002A020 44 54 00 58 00 54 00 00 00 FF FF 0F 00 43 FF FF DT.X.T...ÿÿ..Cÿÿ
0002A030 FF FF FF FF FF FF FF FF FF FF 00 00 FF FF FF FF ÿÿÿÿÿÿÿÿÿÿ..ÿÿÿÿ
0002A040 03 52 00 59 00 20 00 4C 00 4F 00 0F 00 43 4E 00 .R.Y. .L.O...CN.
0002A050 47 00 20 00 4E 00 41 00 4D 00 00 00 45 00 2E 00 G. .N.A.M...E...
0002A060 02 41 00 4D 00 50 00 4C 00 45 00 0F 00 43 20 00 .A.M.P.L.E...C .
0002A070 4F 00 46 00 20 00 41 00 20 00 00 00 56 00 45 00 O.F. .A. ...V.E.
0002A080 01 54 00 48 00 49 00 53 00 20 00 0F 00 43 49 00 .T.H.I.S. ...CI.
0002A090 53 00 20 00 41 00 4E 00 20 00 00 00 45 00 58 00 S. .A.N. ...E.X.
0002A020 54 48 49 53 49 53 7E 31 54 58 54 20 00 92 9D 81 THISIS~1TXT .’••
0002A0B0 8D 3B 8D 3B 00 00 A0 8C 8C 3B 03 00 0E 00 00 00 •;•;.. ŒŒ;......
0002A0C0 53 48 4F 52 54 46 4C 44 20 20 20 10 00 72 A3 81 SHORTFLD ..r£•
0002A0D0 8D 3B 8D 3B 00 00 A4 81 8D 3B 04 00 00 00 00 00 •;•;..¤••;......
0002A0E0 42 41 00 4D 00 45 00 00 00 FF FF 0F 00 68 FF FF BA.M.E...ÿÿ..hÿÿ
0002A0F0 FF FF FF FF FF FF FF FF FF FF 00 00 FF FF FF FF ÿÿÿÿÿÿÿÿÿÿ..ÿÿÿÿ
0002A100 01 4C 00 4F 00 4E 00 47 00 20 00 0F 00 68 46 00 .L.O.N.G. ...hF.
0002A110 4F 00 4C 00 44 00 45 00 52 00 00 00 20 00 4E 00 O.L.D.E.R... .N.
0002A120 4C 4F 4E 47 46 4F 7E 31 20 20 20 10 00 4E A7 81 LONGFO~1 ..N§•
0002A130 8D 3B 8D 3B 00 00 A8 81 8D 3B 05 00 00 00 00 00 •;•;..¨••;......
0002A140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Relevant information:
Entry 1 at 0x2A000 is a file entry (FA at 0x2A00B = 0x20 – Archive bit). As the file has a short
name it is entered directly in the DOS file name field. In this case “SHORT.TXT”
Entries 2 to 5 starting at 0x2A020 are dummy LFN entries (FA at 0x2A02B = 0x0F – RO + Hidden
+ System + Volume). This is where the long name is coded using UTF-16 Format. The name is
scattered in each record (shown in blue above). The first byte of each entry is the sequence
number.
Entry 6 starting at 0x2A020 is the actual descriptor for the file (FA at 0x2A02B = 20) with the long
file name. The name field contains a short (and unique) 8.3 equivalent of the long name. In this
case “THISIS~1.TXT”.
If we now remove the first file with the long file name, the directory table is modified as follow:
Offset 0 1 2 3 4 5 6 7 8 9 A B C D E F
0002A020 E5 54 00 58 00 54 00 00 00 FF FF 0F 00 43 FF FF åT.X.T...ÿÿ..Cÿÿ
0002A030 FF FF FF FF FF FF FF FF FF FF 00 00 FF FF FF FF ÿÿÿÿÿÿÿÿÿÿ..ÿÿÿÿ
0002A040 E5 52 00 59 00 20 00 4C 00 4F 00 0F 00 43 4E 00 åR.Y. .L.O...CN.
0002A050 47 00 20 00 4E 00 41 00 4D 00 00 00 45 00 2E 00 G. .N.A.M...E...
0002A060 E5 41 00 4D 00 50 00 4C 00 45 00 0F 00 43 20 00 åA.M.P.L.E...C .
0002A070 4F 00 46 00 20 00 41 00 20 00 00 00 56 00 45 00 O.F. .A. ...V.E.
0002A080 E5 54 00 48 00 49 00 53 00 20 00 0F 00 43 49 00 åT.H.I.S. ...CI.
0002A090 53 00 20 00 41 00 4E 00 20 00 00 00 45 00 58 00 S. .A.N. ...E.X.
0002A0A0 E5 48 49 53 49 53 7E 31 54 58 54 20 00 92 9D 81 åHISIS~1TXT .’••
0002A0B0 8D 3B 8D 3B 00 00 A0 8C 8C 3B 03 00 0E 00 00 00 •;•;.. ŒŒ;......
We can see that not only the entry for the actual file at 0x2A0A0 is marked as erased (0xE5) but all the
dummy LFN entries (0x2A020, 0x2A040, 0x2A060, 0x2A080) are also marked as erased.