anchor.diff:        (setf (isa-pic-irq-mask +ps/2-aux-irq+) nil))
       ;; Flush data FIFOs.
       (ps/2-flush-input :key)
  -    (ps/2-flush-input :aux)
  -    (format t "Config word: ~8,'0B  KEY: ~S  AUX: ~S (after setup)~%"
  -            (ps/2-read-config)
  -            *ps/2-key-port-working*
  -            *ps/2-aux-port-working*)))
  +    (ps/2-flush-input :aux)))
   
   (defun ps/2-write (port byte)
     (ecase port
  
positive.code:       (setf (io-port/8 +ps/2-control-port+) +ps/2-enable-aux-port+)
        ;; This bit should be clear now, for a dual-channel controller.
        (setf config-byte (ps/2-read-config))
        (format t "Config word: ~8,'0B (after aux enable)~%" config-byte)
        (when (logtest config-byte +ps/2-config-aux-clock+)
          (setf single-channelp t))
        (ps/2-input-wait "disable-aux")
  
negative.code:     (ps/2-write-config (logior (ps/2-read-config)
                                 (if *ps/2-key-port-working* +ps/2-config-key-interrupt+ 0)
                                 (if *ps/2-aux-port-working* +ps/2-config-aux-interrupt+ 0)))
      (setf *ps/2-key-port-working* t
            *ps/2-aux-port-working* t)
      ;; Enable ports.
  