One way to recover from a “missing operating system” message

Prerequisites: You’ll need a Windows 98 Startup Disk 

I was trying to install Red Hat Linux 8 over DeLi Linux and in the process I somehow corrupted the Master Boot Record (mbr).  I probably ruined the boot up code in the hard drive when I issued “fdisk /mbr ” .    After that, I simply could not install anything into my hard drive.  Everytime I tried to boot up the computer straight from the main hard drive(C:), without the Win 98 Startup Disk, I was getting “Missing operating system.” messages.  Even after multiple fdisk /mbr commands, I still couldn’t fix the hard drive or initialize the mbr properly.  I couldn’t even format the C: drive with a DOS “format c: /s” command.

Lucky for me, there is a program called DEBUG.EXE in the Windows 98 Startup Disk that helped me out.  By the way, Startup Disks built by Windows XP don’t have this program.  When booting the computer using the Win 98 Startup Disk, copies of useful programs are copied to the C: drive including DEBUG.EXE.  Using this program, I was able to clear out the MBR on the hard drive.  This article will describe how I did this.

Caution/Disclaimer: Doing the following will cause your hard drive to start from scratch and you will lose data that was originally on your hard drive. I’m not responsible for any loss of data.

1. Boot the computer using a Windows 98 Startup Disk.  During boot, programs will be copied to your main drive (C:) including one called DEBUG.EXE
2. After boot completes, change to the C: drive by typing “C:” at the A:> prompt
3. Enter “debug” at the C: prompt
4. At the “-” prompt, type ‘a’ to start the assembly editor
5. Enter the following assembly code instructions:
6. mov dx,9000
   mov es,dx
   xor bx,bx
   mov cx,0001
   mov dx,0080
   mov ax,0301
   int 13
   int 20
7. then press ‘g’ to execute
8. If everything goes right, a critical area in your hard drive containing the MBR has now been cleared to zeroes and is ready for a fresh new Operating System installation.