Found
int 0x13
with
mov ah,0x42

Help. if you know what it is

IBM/MS INT 13 Extensions - EXTENDED READ
AH = 42h
DL = drive number
DS:SI -> disk address packet (see #00272)
Return:CF clear if successful
AH = 00h
CF set on error
AH = error code (see #00234)
disk address packet's block count field set to number of blocks
successfully transferred

See Also: AH=02h - AH=41h"INT 13 Ext" - AH=43h"INT 13 Ext"


Format of disk address packet:

Offset Size Description (Table 00272)
00h BYTE size of packet (10h or 18h)
01h BYTE reserved (0)
02h WORD number of blocks to transfer (max 007Fh for Phoenix EDD)
04h DWORD -> transfer buffer
08h QWORD starting absolute block number
(for non-LBA devices, compute as
(Cylinder*NumHeads + SelectedHead) * SectorPerTrack +
SelectedSector - 1
10h QWORD (EDD-3.0, optional) 64-bit flat address of transfer buffer;
used if DWORD at 04h is FFFFh:FFFFh

Thanks

Thats not all. I also found AH=40,AH=41,AH=45 in WinNT bootsector
(I Disasembled it ).

I would prefer http://www.ctyme.com/intr/int-13.htm