CLXCON2

         This reg controls when bit planes 7 and 8 are included in collision
         detection, and there required state if included. Contents of this
         register are reset by a write to CLXCON.


         BITS INITIALIZED BY RESET


         +-------+----------+-----------------------------------------------+
         | BIT#  | FUNCTION | DESCRIPTION                                   |
         +-------+----------+-----------------------------------------------+
         | 15-08 |          | unused                                        |
         | 07    | ENBP8    | Enable bit plane 8 (match reqd. for           |
         |       |          | collision)                                    |
         | 06    | ENBP7    | Enable bit plane 7 (match reqd. for           |
         |       |          | collision)                                    |
         | 05-02 |          | unused                                        |
         | 01    | MVBP8    | Match value for bit plane 8 collision         |
         | 00    | MVBP7    | Match value for bit plane 7 collision         |
         +-------+----------+-----------------------------------------------+


   Note: Disable bit planes cannot prevent collisions. Therefore if all
         bitplanes are disabled, collision will be continuous, regardless
         of the match values.