anchor.diff:                ;; Key press.
                 (cond ((eql key :shift)
                        (setf *ps/2-keyboard-shifted* t))
  +                    ((eql key :control)
  +                     (setf *ps/2-keyboard-ctrled* t))
  +                    ((eql key :meta)
  +                     (setf *ps/2-keyboard-metaed* t))
                       ((characterp key)
  +                     (when *ps/2-keyboard-ctrled*
  +                       (setf (char-bit key :control) t))
  +                     (when *ps/2-keyboard-metaed*
  +                       (setf (char-bit key :meta) t))
                        (return key))
                       ((null key)
                        (write-string "Unknown keycode #x")
  
positive.code: (defclass ps/2-keyboard-stream (stream-object) ())
  
  (defvar *ps/2-keyboard-shifted* nil)
  (defun ps/2-read-char (fifo)
    (loop
       (let* ((scancode (ps/2-read-fifo fifo))
  
negative.code:        (cond ((logtest scancode #x80)
                ;; Key release.
                (when (eql key :shift)
                  (setf *ps/2-keyboard-shifted* nil))
                (when (eql key :control)
                  (setf *ps/2-keyboard-ctrled* nil))
                (when (eql key :meta)
                  (setf *ps/2-keyboard-metaed* nil)))
               (t ;; Key press.
                (cond ((eql key :shift)
                       (setf *ps/2-keyboard-shifted* t))
                      ((eql key :control)
                       (setf *ps/2-keyboard-ctrled* t))
                      ((eql key :meta)
                       (setf *ps/2-keyboard-metaed* t))
                      ((characterp key)
                       (return t)))))
         (incf (ps/2-fifo-head fifo))
  