anchor.diff:      (setf (sys.int::io-port/8 (+ (ata-controller-command controller)
                                    +ata-register-device+))
             (logior (ecase (ata-device-channel device)
  -                    (:master 0)
  -                    (:slave +ata-dev+))
  +                    (:device-0 0)
  +                    (:device-1 +ata-dev+))
                     +ata-lba+
                     (ldb (byte 4 24) lba)))
       ;; HI4: Write_command
  
positive.code:                     controller
                      :exclusive t)
      ;; Probe drives.
      (ata-detect-drive controller :master)
      (ata-detect-drive controller :slave)
      ;; Enable controller interrupts.
      (setf (sys.int::io-port/8 (+ control-base +ata-register-device-control+)) 0)))
  
  
negative.code:       (wr +ata-register-lba-mid+  (ldb (byte 8 8) lba))
        (wr +ata-register-lba-low+  (ldb (byte 8 0) lba))
        (wr +ata-register-device+ (logior (ecase (ata-device-channel device)
                                            (:device-0 0)
                                            (:device-1 +ata-dev+))
                                          +ata-lba+))
        ;; HI4: Write_command
        (wr +ata-register-command+ command)))
  