and then decide how to react for each location. Since HITCLR and collision detection is real-time, Display List Interrupts can divide the display into sections with HITCLR used at the beginning of each section and separate collision evaluation at the end of each section. When the "fifth Player" option is enabled (See PRIOR/GPRIOR register) the only change is the Missiles 0 to 3 switch from displaying the color of the associated Player object to displaying the value of COLPF3. The new "Player's" collisions are still reported for the individual Missiles. Player/Missile to Playfield Collisions Each bit indicates a pixel of the Player/Missile object has intersected a pixel of the specified Playfield color object. There is no collision registered for the background color. Obscured intersections will also register collisions. If a Player/Missile object priority is behind a Playfield color register and another Player/Missile object priority is higher (foreground) than the Playfield, and the foreground Player/Missile pixels obscure both the Playfield and the Player/Missile object behind the Playfield, then the collision between the Playfield and both the background and foreground Player/Missile objects will register. High-resolution, 1/2 color clock pixel modes (ANTIC Modes 2, 3, and F) are treated differently. The "background" color rendered as COLPF2 where pixel values are 0 does not register a collision. High-resolution pixels are rendered as the luminance value from COLPF1. The pixels are grouped together in color clock-wide pairs (pixels 0 and 1, pixels 2 and 3, continuing to pixels 318 and 319). Where either pixel of the pair is 1 a collision is detected between the Player or Missile pixels and Playfield color COLPF2. GTIA modes 9 and 11 do not process playfield collisions. In GTIA mode 10 Playfield collisions will register where Playfield pixels use COLPF0 through COLPF3 M0PF $D000 Read Missile 0 to Playfield collisions M1PF $D001 Read Missile 1 to Playfield collisions M2PF $D002 Read Missile 2 to Playfield collisions M3PF $D003 Read Missile 3 to Playfield collisions P0PF $D004 Read Player 0 to Playfield collisions P1PF $D005 Read Player 1 to Playfield collisions P2PF $D006 Read Player 2 to Playfield collisions P3PF $D007 Read Player 3 to Playfield collisions Missile to Player Collisions Missiles collide with Players and Playfields. There is no Missile to Missile collision. M0PL $D008 Read Missile 0 to Player collisions M1PL $D009 Read Missile 1 to Player collisions M2PL $D00A Read Missile 2 to Player collisions M3PL $D00B