I created a Windows PE RAM disk (CD-ROM) from the instructions on technet. I'm on a Windows 7 x64 system and my "reference" system is the same. I changed the boot priority to CD-ROM first on the reference system, but it comes up with an error message like
The boot device is not recognized
The instructions in step 2 leaves out one important step. You must copy a
boot.wim
into thesources
directory. The command would be something likeI've taken the liberty of scripting the entire process (for ISOs on x86 and x64 architectures with imagex support). You can pick up the scripts on my github repo or as a chocolatey package.
(Shamelessly copied from a comment at the bottom of the technet article.)