Eltorito.sys - Hardware independent Dos CD-Rom device driver
Last updated: Oct 28, 2002
Important notice: the development and maintenance for this page has stopped. Please don't contact me about this page! I'm leaving the page as it is, for reference...
What is Eltorito.sys?
Eltorito.sys is a Dos CD-Rom device driver for use in making
PC-bootable CD-Roms that (should) boot on any interface
(Atapi and SCSI).
Eltorito.sys will only work when your
CD-Rom is in "no emulation" mode,
it will not work in floppy or harddisk emulation mode!
To get your CD-Rom in "no emulation" you
use some bootstrap loader,
like isolinux.bin or diskem1x.bin!
Eltorito.sys (together with diskemu.bin
was originally developed by Gary Tong. Bart took over the
diskemu/eltorito project in May 5, 2001. Diskemu.bin (or diskem1x.bin) is
not being developed anymore, eltorito.sys is (when needed).
Use this link to download the current version of
To use the eltorito.sys driver the best thing is to follow
and only use the "cdrom.img" bootimage, just leave
out the other boot images like cdrom, msnet and tomsrtbt.
Oct 28, 2002
- I've worked together with some people at Dell to fix their BIOS problems.
They say that they got their BIOSes fixed.
They gave me a very nice notebook (Latitude C400) for my efforts... I wanna thank Dell for that!
Jul 29, 2002 - v1.4
- Major bugfix.
There was a bug in the drive number scan routine that would start the scan
from a "wild" value left in DL register (jump to wrong label).
I synchronized the drive number scan with the subroutine used in ettool.com
(that one worked OK, now also easier to maintain...) so it is fixed!!!
Thanks to Pete Woytovech from Dell for helping me fix this!
Jun 28, 2002 - v1.3b
Jun 27, 2002 - v1.3
- Did some more "workarounds", should work now even on Compaq and
Dell PC's with the worst possible BIOSes.
Jun 6, 2002 - v1.2
- Eltorito.sys does now also finds the correct driver number for the
booted CD-Rom on a Dell PC with very buggy BIOS. The Dell BIOS does
not clear the carry flag after a succesfull eltorito status call (int13/ax=4b01h).
Eltorito.sys now ignores the carry flag, and looks at the specification packet size field.
Other PC's also using Phoenix BIOS version 1.10, or alike maybe also
benefit from this "workaround".
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