Atari XL User Manual

140 The Ateri XL Handbook
6 Then use the command XIO 18, #6,0,0, "S:".
This program draws a solid rectangle on the mode 5
display in colour number 1, with its corners at (5,
5), (75, 5), (5, 75)
and (75,75):
10
REM FILL WITH XIO
100
GRAPHICS 5
110 COLOR 1
120
PLOT 75,
35
130
DRAWTO 75, 5
140
DRAWTO 5,
5
150
POSITION 5,
35
160
POKE 765, 1
170
XIO 18, #6,
0, 0,
"S:"
You can fill shapes other than rectangles, within
certain limits:
1 The bottom of the shape must be horizontal, and
2 The top must be horizontal, or slope down to the
right.
This is because of the way the shapes are filled.
The XL fills in the colour by drawing horizontal
lines to the right from a line between the top left-
hand corner and the bottom left-hand corner, as far
as the line defining the right-hand edge. This
means that if the top of your shape slopes up to the
right it won't all get filled. If the bottom left-hand
coner is higher than the bottom right-hand corner
then not all the shape is filled. If the bottom. left-
hand corner is lower than the bottom right-hand
corner then the colour spills out across the full
width of the screen.
The next program uses XIO to fill random blocks
on the screen, producing instant abstract art. The

Atari XL Specifications

General

Release Year	1983
CPU	MOS Technology 6502C
Graphics	ANTIC, GTIA
Sound	POKEY (4 channels)
Storage	Cassette tape
Ports	Cartridge
Operating System	Atari BASIC
CPU Speed	1.79 MHz
RAM	64 KB