I have a an original Windows 7 Professional x86 iso file, straight from Microsoft. I want to make a bootable USB from this ISO. Some sources suggest that I simply dd the iso to the USB, but I don't see how that should work. The ISO's first 32768 bytes (reserved as System Area on ISO 9660 media, to be used fx for MBR) are all zeroes, so there is no MBR or anything for the BIOS to read.
So as far as I can understand, one way is to add a MBR in this System Area, so that the ISO can be both dd'ed to a USB or written to an optical media, and be bootable from both.
I think the tool isohybrid should do that trick. I don't know how it works, so I can't figure out if it should just work for all bootable (ie bootable if written to optical media) ISO 9660 files. Or does it only work for some specific/familiar iso files?
At least I can't make it work with my Windows 7 iso. I get the following error:
$ isohybrid win7.iso isohybrid: win7.iso: unexpected boot catalogue parameters