in order for an .iso to behave as a disc you need software emulation, you cannot get software emulation without having a running OS as easy to boot alternatives like DOS will not support emulation such as daemon tools there may be specialized software that allows for this but I don't know of any off the top of my head. Honestly just burn the iso to a CD with another computer and your fine You could just take your portable HDD to a bud and have him do it there, daemon tools is free
i duno if its from a external hdd, cause its connected via usb im assuming, and it needs to load something to detect it.
Your logic if flawed there cix, because ALL hardware needs something to detect it technically. Of course, this paradox has already been solved by the bootloader, but that's besides the point I know its possible to boot off of USBs nowadays (not as easily as CDs, but still possible). However, I don't know if this applies to external HDs
CD detection is programed into the BIOS which is firmware I've heard of USB booting as well but I don't know how they make it work unless it's supported by a new bios still I dont' see how using an .iso would work unless there something new for that as well
"The PC has to support booting from a USB flash drive. There may be anywhere from 1-3 items to change in the BIOS to make this possible..." Yep, thought so. Here is the clincher. Since you are running no OS, just the firmware off your Bios you have to have a Bios new enough to run it. Messing with the Bios is a pain...seriously consider a boot CD if it is at all possible. If you already have it supported it doesn't look any different then any normal boot disc/cd.