Making a bootable CD-ROM

Posted on 1998-11-28
Last Modified: 2013-12-28
How do I make a CD bootable?
Question by:steath_acid
  • 2
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Expert Comment

ID: 1648080
Directions can be found here:

Author Comment

ID: 1648081
Nope I would like to boot the CD without a floppy I knew how to do that, I am trying to eleminate the slow floppy drive.

Accepted Solution

harley47 earned 50 total points
ID: 1648082
1. Make an image file from a bootable floppy (or hard) Disk
For preparing the bootable floppy disk, you can make a multi-booting menu in config.sys. The CDROM drivers and mscdex.exe should also be placed in the config.sys and autoexec.bat, and it's better to use several different drivers in the multi-booting menu, so you can use this CD in many different CDROM drives. If you do not include the CDROM drivers, then you will only find a simulated A: drive after booted from the CD. If you have set that driver, then you will find a simulated A: and a normal CDROM (for example: E:). Just remember: the simulated A: is handled by BIOS, it's a restoring of osboot.img, the other files "outside" the bootable image can only be found after the CDROM drived.
Steps for making an image file from that disk:
Two methods:
I. Use Norton's DISKEDIT.EXE. Procedures of mouse clicking are:
1. Object -> Drive -> A (or B or C)
2. Object -> Physical Sector -> OK
3. Tools -> Write Object to -> To a File -> ( setting file name ) -> Yes
The file name is supposed to be OSBOOT.IMG.
II. Use getbtimg.exe
You can get this file : It's much faster than NU's diskedit.exe.
2. Make a file named BOOTCAT.BIN
(You can also download it from directly and skip the following procedures for making this file.)
1. Create a file of 2048 bytes in any form.
2. Use diskedit.exe to edit its hex codes with the beginning like this:
01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 AA 55 55 AA
88 02 00 00 00 00 01 00 BB
The rest of this file must be filled with hex 0.
( The last "BB" has no meaning. It's only used for noting where to place the address codes of osboot.img.)
3. Create the ISO File
(Someone asked me what is an "ISO file"? If you are new in this field of CDR, I suggest you read the readme or help of your favorite CDR software firstly! You can easily understand what it means. For WinOnCD 3.0, it's a "*.raw file", and it's the same as EasyCD Pro's "ISO file".)
Use any CDR software you like. But there is one important thing , the 2 files we have just made must be located at the first place of the ISO image file. You can achieve this by " drag and drop " these two files to the window of the CDR software firstly. (It's better to drag bootcat.bin firstly, then drag osboot.img secondly.) And after that, drag the other files and directories which will be written on the CD. This is because I have an experience when I put these 2 files at the last place of the ISO file, it will not be bootable in IDE CDROM drive, but boots very well in SCSI CDROM drive. If I put them at the first place, then bootable both. I don't know why this happened. I guess it's caused by the BIOS that has some bugs for handling bootable CD.
4. Modify the ISO File
Start Norton's diskedit.exe.
(1). Find ASCII string "bootcat". After it is found , put your active cursor at character "b" , move the cursor up 2 lines and right 1 space. Write down the next 4 bytes. For example, the cursor on the left screen is located at 15 00 00 00 , then write down "15 00 00 00" on a paper for later use.
(2). Find ASCII string "osboot". Place cursor on "o", then use the same method to find that 4 bytes. I suppose it is "16 00 00 00".
(3). Find Hex string "AA 55 55 AA", that is the sector occupied by BOOTCAT.BIN file. You will find a "BB" in the 3rd row of this sector on the left screen , from this place fill in the 4 bytes got from finding "osboot" ASCII string (eg: 16 00 00 00)
88 02 00 00 00 00 01 00 BB
Changed to : 88 02 00 00 00 00 01 00 16 00 00 00
And that "02" at the 2nd byte in this row means it's a 1.44 mb floppy bootable image, If you use other media, change it like this:
01 1.2 mb floppy disk
03 2.88 mb floppy disk
04 Hard disk
(4). Edit sector 17 of the ISO file:
Press home key to go back to the beginning ( sector 0 ) of this ISO image file. Then press PageDown key to offset 34816( Decimal), this is the beginning of sector 17. Replacing the hex codes from the beginning of this sector with the following:
00 43 44 30 30 31 01 45 4C 20 54 4F 52 49 54 4F
20 53 50 45 43 49 46 49 43 41 54 49 4F 4E 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 BB
Notice the "BB" in the 5th row from the beginning of this sector, it's the beginning place to put the address codes of bootcat.bin . ( The "BB" has no meaning. It's only used for noting where to place the address codes of bootcat.bin, you can type the address codes directly from the place of "BB".) In our example, it's 15 00 00 00, so, make the 5th row like this:
00 00 00 00 00 00 00 BB
Changed to : 00 00 00 00 00 00 00 15 00 00 00
The rest of this sector ( ended at offset 36863 ) should be replaced by "0".
5. Burn this ISO file to a blank CD
Of course, you have to use "Disc from an image file" writing option in your CDR software. (Someone told me he made a disc only containing a single file named xxx.iso, obviously, it can't boot anyway! ) You can also burn other datas in the second (or any further) session, and it will be still bootable.
6. Test the bootable CD
For IDE CDROM, you just have to change the setting of booting sequence in BIOS to "CDROM, C, A", then reboot the PC with the CD in CDROM drive.
For SCSI CDROM, firstly, the booting sequence in BIOS of motherboard should be changed to "SCSI, IDE". If the BIOS hasn't this option, then you just have to set all the IDE HD to "None". Secondly, enter the BIOS setting of your SCSI card. For example, in Adaptec's AHA 2940U, go into "Advanced Configuration Options", enable the options of "Host Adapter BIOS (Configuration Utility Reserve BIOS Space)" and "BIOS Support for Bootable CDROM". Then reboot the PC.

Hope this helps


Expert Comment

ID: 1648083
You didn't READ the link that I posted.
If you had, you would know that there is no floppy used when booting with the CD.
As with harley's proposed answer, the two boot files are copied from a floppy.

Author Comment

ID: 1648084
Fine though you may be right sorry but if you really want teh points i post you a question otherwise sorry.

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