anchor.diff:      :linux :unix))
   
   (defparameter *architecture-features*
  -  '(:amd64 :x86-64 :x86_64 :i686 :i586 :pentium3 
  -    :i486 :i386 :pc386 :iapx386 :x86 :pentium4
  +  '(:amd64 (:x86-64 :x86_64 :x8664-target) :i686 :i586 :pentium3 
  +    :i486 (:i386 :pc386 :iapx386) (:x86 :x8632-target) :pentium4
       :hppa64 :hppa :ppc64 :ppc32 :powerpc :ppc :sparc64 :sparc))
   
   ;; note to gwking: this is in slime, system-check, and system-check-server too
  
positive.code: 
  
  (defparameter *implementation-features*
    '(:allegro :lispworks :sbcl :openmcl :cmu :clisp :ccl
      :corman :cormanlisp :armedbear :gcl :ecl :scl))
  
  (defparameter *os-features*
  
negative.code: operating system, and hardware architecture."
    (or *implementation-specific-directory-name*
        (setf *implementation-specific-directory-name*
              (labels ((fp (thing)
                         (etypecase thing
                           (symbol
                            (let ((feature (find thing *features*)))
                              (when feature (return-from fp feature))))
                           ;; allows features to be lists of which the first
                           ;; member is the "main name", the rest being aliases
                           (cons
                            (dolist (subf thing)
                              (let ((feature (find subf *features*)))
                                (when feature (return-from fp (first thing))))))))
                       (first-of (features)
                         (loop for f in features
                               when (fp f) return it))
                       (maybe-warn (value fstring &rest args)
                         (cond (value)
                               (t (apply #'warn fstring args)
                                  "unknown"))))
                (let ((lisp (maybe-warn (first-of *implementation-features*)
                                        "No implementation feature found in ~a." 
                                        *implementation-features*))
  