All the Details of various
versions of MBR and
OS Boot Records

These pages will probably always be in a state of flux (change) as I keep gathering new data for Boot Records, filling in Assembly code comments and adding important topics related to booting up your box!


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HELP: If you live in the USA and have an old 32MB (or larger) SDRAM Memory DIMM (PC100/10ns) to donate, we could sure use it!  Our present system is an AMD K6-2 at 400MHz (which was also donated... Thank you again Rob!), but we're unable to test a new OS that requires a minimum of 128MB RAM (we need at least 32MB more in the last empty slot); plus a number of applications that are severely limited without more memory. We've FLASHED the BIOS on this old M577 Motherboard twice already!!

Personalized Data Recovery help via E-Mail for a reasonable fee.

Index to MBR and OS Boot Records (with COLOR highlighting):

Start Here:

   As either a review or an introduction (for those who need to know definitions and explanations of these terms), it's strongly suggested that everyone  START HERE :  Understanding Disk Drive Terminology [for both Hard and Floppy Disk drives]. These terminology pages include many useful details (even experienced techs should read them!) such as: How do you calculate the exact capacity of a floppy disk or hard drive?, Why do some utilities show less drive capacity than what's printed on the HDD?, What do MiB and GiB mean? and Do you know that partitioning a drive on a computer with a BIOS made earlier than 1999 will most likely waste drive space for an archaic structure known as the Test Cylinder?

Understanding Partition Tables
-- A new page that's still being worked on but very useful as is!

Some Miscellaneous Topics:

An Introduction to Data Recovery.

How To Permanently Erase ALL the DATA On A Hard Disk -- without destroying it!

How to change your BOOT.INI Menus under Win2000/XP

How many Sectors are on a Hard Drive? -- Contains useful tables for picturing the contents of your hard drive.

HDD and OS Disk Limits: 32GB, 64GB, 137GB etc.!!!

Free Software:

References. Links. Free Tools, Utilities and Boot Managers:
 MBR, Partition Table and Boot Record Tools and Links .

MBRs (Master Boot Records)

All about FDISK.EXE -- Covers all versions of Microsoft's FDISK executables. UNIX/Linux and other OSs have similar 'fdisk' programs that are not as dangerous to your data as Microsoft's FDISK; read the next selection about how it destroys data!  [NOTE: Under Windows™ 2000/XP, you do not have an FDISK program for setting up your drives.  Instead, you must use: 1) The install CD when setting up a new system, 2) the Disk Management "MMC Snap-In" program, 3) An old Win98 Boot Diskette for FAT32 partitions only, or 4) possibly the Recovery Console's command: fixmbr (on the install CD).]

The Windows 2000/XP MBR -- The MBR created by a running Windows 2000 or XP OS (specifically Disk Management) when used to install a completely blank hard drive on your system; includes details about the Win 2k/XP Disk Signature bytes!

The Windows MBR for FAT32 -- The MBR created by FDISK from Windows 95B (or OSR2), Windows 98/98SE and even Windows ME.

The Standard MBR --- This is the Master Boot Record that's placed on the first sector of any hard disk partitioned by FDISK.EXE (or FDISK.COM) from all versions of MS-DOS back to MS-DOS 3.30 (including DOS 6.22 and MS-Windows 95 "A" also known as MS-DOS 7.0).

This is also the same as the Standard IPL (or MBR) code used by the Ranish Partition Manager, TestDisk and some boot managers when there's a problem that requires the MBR code to be written again.

Notes on DOS 3.30 and an early (1988) OEM version -- The Master Boot Record created by the NEC® (Revision 3) version of MS-DOS 3.30's FDISK was slightly different than that of all the other MS-DOS 3.30 MBRs (in order to allow it to have 8 Partition entries in its Partition Table). Some important points about DOS MBRs in general are also included here.

The Ranish MBR/Compact Boot Manager -- Single sector MBR replacement included with the Ranish Partition Manager.
Preliminary Listing.


The IBM® Personal Computer™ DOS 2.00 MBR and How Similar it is to the Standard MBR (of DOS 3.30) --- The Master Boot Record created by IBM®'s DOS 2.00; showing each byte of code that's different from the Standard MBR.


OS Boot Records

All about SYS.COM - Shows details of all versions of Microsoft's SYS.COM program which can be used to create both Hard Disk and Floppy Disk OS Boot Records.  [ NOTE: Under the Windows™ 2000/XP/2003 OSs, Hard Disk Boot Records are created by: 1) the install process, 2) the OSs Disk Management program, or 3) possibly by using the Recovery Console command: fixboot. ]

1) The Basics: Floppy Disk Boot Records

MSWIN4.1 (Windows 98) Floppy Disk Boot Record
For Booting the underlying MS-DOS 7.1 of the Windows 98 Operating Systems from a Floppy Diskette. Preliminary Listing.

MS-DOS 5.0 Floppy Disk Boot Record -- For Booting the MS-DOS 5.0 to 6.22 Operating Systems from a floppy diskette.
Preliminary Listing.

MS-DOS 3.30 Floppy Disk Boot Record -- For Booting the DOS 3.30 Operating System from a floppy diskette.
[Sorry, may never bother with this one.]

2) Hard Disk OS Boot Records

The NTFS Boot Record: Boot Sector - The Windows 2000 (NT5.0) and XP (NT5.1) Boot Record; including the NTFS BPB (BIOS Parameter Block). Link to "The Disk Editor View page" to view the Record as it would be seen in a disk editor.

The NTFS Boot Record: Bootstrap Code - The Windows 2000 (NT5.0) and XP (NT5.1) "Bootstrap" Sectors. . . which we refer to as the NTLDR Section of the NTFS Boot Record Preliminary Listing !

MSWIN4.1 Boot Record - For the Windows 95B, 98 and 98SE and ME OS (or FAT32) Boot Records; including the BPB (BIOS Parameter Block).

Boot Managers (MBRs)

LILO (Linux Loader) Boot Manager's MBR --  This used to be the only Boot Manager for the Linux OS, and it is still the best choice for many Linux projects such as a Linux Boot Disk Rescue System.

GRUB - The GRand Unified Boot Manager! --  This one is now the default Boot Manager for some distros such as Red Hat. You may even consider using this Boot Manager for Microsoft OSs (after installing a small Linux /boot partition for the GRUB executable and support files); this is how The Starman runs his own multi-boot system.

The Windows™ 2000/XP/2003 BOOT.INI Menu system
This is related to various system files, such as NTLDR, which may even appear in a Windows 98/ME partition if you install Win XP/2000/2003 onto the same computer!

The Ranish Advanced Boot Manager -- well, for now, I've decided that this code isn't as important as other managers!


Confused? Send me an e-mail if you have a specific question about the MBR or other Boot Records...


Last Update: June 1, 2004.

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