It works fine for me in qemu and VirtualBox. I don't need to select anything special. But I am not able to see the qemu/VirtualBox CD drive.
Thanks for fdubcd.iso.gz. Got it working under VMWare (Player 3.0.1) with the same behaviour (T: => emulated CDROM drive; cannot see physical CDROM drive).
I can see the difference is that fdubcd.iso.gz uses isolinux as the bootloader, which in turn boots fdubcd.img using memdisk, whereas my fdubcd.iso uses fdubcd.img as the boot image. My tiny brain is exploding under all this complexity.
Do you know why the former assigns T: => emulated CDROM drive, while the latter assigns T: => physical CDROM drive?
I found a bug in the implementation of mdiskchk.com in autoexec.bat
Got it! Updated autoexec.bat.
Anyway, I think this approach has potential for those booting from USB CDROM drives or memory stick but have problems getting their source devices recognized under FreeDOS. There might be side effects though that will require further testing, plus we need to write scripts to generate fdubcd.iso.gz, plus we need to settle on the steps to add customized FreeDOS apps so that upgrading to a new version of UBCD is as easy as possible, so let's explore this in the next release.