FInding the System (preferences) folder...

[Thad.Humphries@p0.f716.n109.z1.FidoNet.Org (Thad Humphries)]

Maybe I'm just being stupid, but how do I find the volume number of the
> Boot (System) Volume.
> I need that to call #_FindFolder, I think.
> "TANSTAAFL" Rich lynch@ils.nwu.edu

I might not understand all you are trying to do, but I stumbled across a ccl command when trying to build a load file that worked regardless of the hard disk name:

(def-logical-directory "CS681;" 
  (concatenate 'string (cadr (pathname-directory (ccl::startup-directory)))
               ":Development:CS681:"))


ccl::startup-directory returns the directory where MCL 2.0b1p3 is and 
(cadr (pathname-directory (ccl::startup-directory)) extracts the hard drive name from that.  My book is at home, but I believe the Files chapter tells you how to get a volume number from that.

Being "hidden" in ccl::, this might not work with future releases.  And, of course, if MCL isn't on the drive with the booted System folder, this won't help you find the current Preferences folder.