Я ненавижу компоненты, поэтому вот код
var
RawMBR : array [0..511] of byte;
btsIO : DWORD;
begin
hDevice := CreateFile('\\.\PHYSICALDRIVE1', GENERIC_READ,
FILE_SHARE_READ or FILE_SHARE_WRITE, nil, OPEN_EXISTING, 0, 0);
if hDevice <> INVALID_HANDLE_VALUE then
begin
SetFilePointer(hDevice,512 * 0,nil,FILE_BEGIN); // replace 0 with sector that you wish to read
ReadFile(hDevice, RawMBR[0], 512, btsIO, nil);
CloseHandle(hDevice);
end;
end;