ISOBOOT is automatically used if a linux ISO file is not contiguous and the ISO file is smaller than the \_ISO\CONTIG.ISO file (if present) and if the filename of the linux ISO is recognised by the isoboot.g4b batch file code!
ISOBOOT is also used if the E2B USB drive is write-protected or E2B is booted from a CD/DVD, because ISOBOOT does not modify the contents of the boot drive.
Tip: If you hold down the SHIFT key before pressing ENTER in the E2B Menu, it will run ISOBOOT on that file immediately, even if the file is contiguous. This provides an easy way to test ISOBOOT with your ISO file.
isoboot.g4b is a grub4dos batch file that attempts to boot from a linux ISO by using linux 'cheat codes' which specify the name of the ISO file, so that linux can find and access the files inside the ISO file. This is similar to the 'old' standard way of booting ISOs (as used by YUMI, SARDU, PenDriveLinux, XBoot, etc.).
As these cheat codes change from distro to distro and even from version to version, it may not always work. 
ISOBOOT is a 'final attempt' to try to boot a linux ISO before E2B gives up!
E2B would probably be able to boot it just fine if the ISO file was contiguous.
If you are experienced with these cheat codes and grub4dos, you can make your own version of isoboot.g4b:
1. Copy the \_ISO\e2b\grub\isoboot.g4b file to the \_ISO folder
2. Edit the \_ISO\isoboot.g4b file using NotePad (it will now always be used instead of the E2B version)
e.g. an ISO file with 'mint' in it's filename will run the code under the :.isomint label.
You can edit the lines under the :.isomint label and change the kernel parameters
if exist seed     && echo kernel %kernel%   %seed% boot=casper  iso-scan/filename=%ISOSCAN% -- > (md)0x220+1
echo initrd %initrd%  >> (md)0x220+1

To suppress the pause when isoboot runs, use (v1.78+)

set NOSUG=1


set redir=> nul

in your \_ISO\MyE2B.cfg file.

  • NOSUG will also prevent QRUN.g4b file extension suggestions from being displayed as well as the pause during isoboot.
  • redir suppresses most E2B informational (non-essential) messages in E2B.