583-622



     printer suffers from this malady as well) happens when your drive
     times out, or the timer value reaches zero. This has been cured
     by the new OS "B" version ROMs.

583-622        247-26E        LINBUF
     Forty-byte character line buffer, used to temporarily buffer one
     physical line of text when the screen editor is moving screen
     data. The pointer to this buffer is stored in 100, 101 ($64, $65)
     during the routine.

623            26F            GPRIOR
     Priority selection register, shadow for 53275 ($D01B). Priority
     options select which screen objects will be "in front" of others. It
     also enables you to use all four missiles as a fifth player and
     allows certain overlapping players to have different colors in the
     areas of overlap. You add your options up as in location 559,
     prior to POKEing the total into 623. In this case, choose only one
     of the four priorities stated at the beginning. BAK is the
     background or border. You can also use this location to select
     one of GTIA GRAPHICS modes nine, ten, or eleven.

     Priority options in order                      Decimal   Bit
     Player 0 - 3, playfield 0 - 3, BAK
         (background)                                   1      0
     Player 0 - 1, playfield 0 - 3, player 2 - 3,
       BAK                                              2      1
     Playfield 0 - 3, player 0 - 3, BAK                 4      2
     Playfield 0 - 1, player 0 - 3, playfield 2 -3,
       BAK                                              8      3
     Other options
     Four missiles = fifth player                      16      4
     Overlaps of players have 3rd color                32      5
     GRAPHICS 9  (GTIA mode)                           64      6
     GRAPHICS 10 (GTIA mode)                          128      7
     GRAPHICS 11 (GTIA mode)                          192     6, 7

     It is quite easy to set conflicting priorities for players and
     playfields. In such a case, areas where both overlap when a
     conflict occurs will turn black. The same happens if the overlap
     option is not chosen.
     With the color/overlap enable, you can get a multicolor player
     by combining players. The Atari performs a logical OR to colors
     of players 0/1 and 2/3 when they overlap. Only the 0/1, 2/3
     combinations are allowed; you will not get a third color when
     players 1 and 3 overlap, for example (you will get black instead).
     If player one is pink and player 0 is blue, the overlap is green. If
     you don't enable the overlap option, the area of overlap for all