Atari XL User Manual

Player-Missile Graphics
173
addition control the relative priorities of the
players, missiles and the background to control
which will show when two objects overlap, and thus
obtain three-dimensional effects.
This simple program shows one player, which
appears as a vertical band on the mode 0 screen.
10 REM SET ADDRESSES FOR PLAYER 0
20 POGRAPH=53261
30 POHPOS=53248
40 POCOL=704
50
POSIZE=53256
90 REM SHOW PLAYER
100 POKE POGRAPH, 255
110 POKE POCOL, 54
120 POKE POSIZE, 3
130 POKE POHPOS, 120
The player (Player 0) is set to a vertical red band by
this program. The properties of the player are
controlled by the contents of the four registers. The
pattern of bits in location 53261 controls the
appearance of the player - the program sets it to
255 to give a solid vertical band (255 is 11111111 in
binary). Try:
POKE 53261, 170
This give four thin stripes down the screen (170 is
10101010 in binary only the positions
corresponding to the Is are shown).
The colour is controlled by location 704, which
works in the same way as the colour registers for
normal graphics. The number in the register
indicates the colour and luminance as follows:
Number = (Colour No.*16) + luminance

Atari XL Specifications

General

Brand	Atari
Model	XL
Category	Desktop
Language	English