For russian variant of this document, see later.
᪨ ਠ  㬥 室   䠩.

MBR loader description.
~~~~~~~~~~~~~~~~~~~~~~
     For now, this text is only available in russian. It will be translated to
english later.


ᠭ MBR-稪.
~~~~~~~~~~~~~~~~~~~~~~~

       稪    室   㫥 ᥪ ࢮ ⪮
᪠  (MBR)    ।祭  㧪 ᥪ ⨢ ࠧ  
ࠧ      ஬   㪠 ⪮ ᪥. MBR, 㧨 
ࢮ  ⪮  ᪠,    ,    ⪮ ᪠ த
㧪  .    ࠭ ⪮ ᪥ 㦠 ᥪ ⨢
ࠧ,   ࠧ  । ஬.  ᫥饣 ⪮ ᪠
    ࠧ      ய뢠      ᥪ MBR 
ࢮ  ⪮ ᪥. ⨢ ࠧ ।  ࢮ  ⥫
ࠧ    ⠡  ࠧ (Partition table  PT). ᫨   ࠢ
80h,  ࠧ ⠥ ⨢, ᫨   ࠢ 00h,  ࠧ ⨢.

       㧪   ࢨ筮 (primary)  ᪮ (logical) ࠧ 
  ஬  ।祭  BootPart  MBR-ᥪ, 饥 ࠧ 
1    ᯮ  MBR  ᬥ饭 0x1bb  砫 ᥪ.  
ய뢠   MBR  ⠭ 稪. ᫨   ࠢ , 
  ,   稪  । ⨢ primary-ࠧ ⪮
᪠,    㧨      ᥪ,  ।    ࠢ. ᫨ 
BootPart 㫥,    㪠 稪 ਭ㤨⥫쭮 
㧮  ࠧ,  ᪨   ࢨ,  ஢  ⨢ 
⠡  ࠧ.    ⮬  砥  ஢ 祭  BootPart. ᫨
BootPart    祭    1    4,      ᫮  ࠪ  
primary-ࠧ.  ᫨    祭    5  ,  BootPart - 4 
஬ ᪮ ᪠  Extended ࠧ.

      ࠧ, ⠪  ᨬ쭮 祭  BootPart ࠢ 255, 
᫮  ᪨  ᪮        0    255  -  4  =  251.  ,
-ᨬ      3  primary-ࠧ  1 extended  251 ᪨
  extended.

       稪 ᯮ LBA  㧪 ᥪ஢  ⪮ ᪠ 
,  ᫨ LBA ন.  ⨢ 砥 ᯮ 㭪 BIOS
 ⥭ ᥪ஢   CHS.

     । ⠡楩 ࠧ,  ᬥ饭 0x1bd, 室  ForceLBA. ᫨
   ࠢ ,  LBA ᯮ ਭ㤨⥫쭮.

     ।  ForceLBA    ᫥  BootPart,    ᬥ饭 0x1bc, ᯮ 
BootDev.    ।  䨧᪮ ன⢮,  ஬ ᪠ 㧮
ࠧ    ᥪ஬.  祭  ⮣    ࠢ  ⪮ ᪠ 
ଠ  int  13h. ਬ,  ⪨    80h, ன 81h 
.  .    㬮砭      ࠢ 80h,  , ந 㧪 
ࢮ ⪮ ᪠  ⥬.

       ࠧ ᯮ 稭  ᫥饣  ForceLBA , 
ᬥ饭  0x1be,  ,  ᮣ᭮  ⠭, ⮨  4- ⥫ ࠧ
ࠧ஬  16  .

     稢  ᥪ  ᨣன  MBR,  ࠢ  0x55aa.      
।祭    ஫  楫⭮ MBR,  ⠪  㤮⢠  ᪥
MBR  ᥪ஢  ⠭   襬 ⪮ ᪥.

       稪  뢮    ਩    ᮮ饭. ࢮ
ᮮ饭  --  "R"  (ࢠ  㪢  ࠧ  "Read error") 뢮  訡
⥭  ᪠,    ,  ᫨   LBA,  CHS   ᯥ譮  
⥭ ᥪ  ᪠.

     饭  "P"  砥  "Partition not found"  뢮, : 1) 
  ⨢  ࠧ   ⠡ ࠧ 2)   ७ ࠧ 
  BootPart  >  4  3)  ᬠਢ  楯  EBR  (Extended boot records),      !!! Fix it
稪    襫  뫪  ᫥ EBR  ⥪ EBR, ᮣ᭮ 祭
  BootPart,   ᫥. 4)   ⥫ 㦭 ࠧ
  EBR  (    祭  ⮬  ⨢  80h).  5)  ⥫  MBR
primary-ࠧ ⮨  㫥   뢠  ࠧ.

     稪    ᪥  (BIOS int 19h 㦠    0x7c0:0x0)
६頥  ᥡ      0x60:0x0  । ࠢ   .
०    稪  (  0x7c0:0x0    0x7e0:0x0  ࠧ஬   ᥪ)
ᯮ        㧪  ᥪ஢.        ६
㦠  MBR  ࢮ  ⪮  ᪠, MBR ᫥饣 ⪮ ᪠, 1-
EBR,  2-  EBR, ..., n- EBR , , ᥪ 㧮筮 ࠧ. ᫥
⮣, ࠢ । ᥪ.

     ࠭⢮   0x7e0:0  0x800:0 ᯮ MBR-稪,  ⠪
ᥪ஬,    ࠭    ६.  ⥪  MBR-稪, 
ᥪ஬ ᯮ ⠪: ss = 0,  ⥪ 樠  0x7bff.

      稪, 㧨 ᥪ, "ࠢ" 祭 hiddensectors
  BPB, ਡ    ࢮ ᥪ  ᪮ ᪠ (⮣
ᠬ ᥪ,  室 EBR,    63 ᥪ  ᥪ). 
  ᮮ⢥騥  BPB ᥪ MBR-稪   䨧᪮
᪠    ,  ᮮ⢥騩  㪢  ᪮  ᪠.   樨
믮          㧪   OS/2      ᪨   ᪮ 
Extended-ࠧ.     樨  믮  OS/2  boot  manager  
㧪  OS/2    ᪨  ᪮.     ⮬,   ᪨ ᪮
祭  hiddensectors  ࠢ  63,    primary-ࠧ  ࠢ ᬥ饭
᪠  砫 䨧᪮ ᪠. ⮬ 筮 ଠ쭠 㧪 
⮫쪮    primary-᪮.  ⮡  OS/2   㧨  ᪮ ᪠ 
⮡  (᫨  ᯮ  pre-LVM    OS/2) 砫 ࠢ쭮 㪢
㧮筮 ᪠, 㦭   ஭ boot manager'.   
⢮    ⬥,  㬥 㧨 OS/2  ᪮ ᪠: 1)
OS/2  bootmanager  2)  ⬥ VPart  Veit' Kannegieser' 3) AirBoot 
Martin'  Kiewitz'.    ᯨ᮪      訬 MBR-稪,
  믮  ஫  -⬥.   MBR-稪  ⫨稥 
饣  ⬥      롮 㧮筮 ࠧ,
  ⮣ 롮 㦠 ࠧ   㤥 ந  FreeLdr,
  㤥  믮  㭪樨  OS Loader'  bootmanager' ६ 
㤥   㧨   blackbox'.   (  ,    㤥  த  
६    OS/2  bootmanager'    os2ldr  ६.    ⠪
ᮢ饭  bootloader'   bootmanager'    GNU GRUB,  
⨬  ᫥  筮  ਭ樯.  २⢮  ⠪ 室 ०
ᥣ    ⮬,            롨      㧪,  
ࠧ  ࠬ  ,        ।  
१  config.sys.  ஬  ⮣,    ᬮ  롨      ᪮쪮
ᨩ/ᡮப   os2ldr,  ⠪ 祭 㤮.).

(c) Valery  Sedletski aka valerius
(c) ਩ 檨 aka valerius,
osFree project, 2006, Oct 10.
