numbers between 0 and 14 define the luminance.
If
you type
an
odd
number, the computer uses the color of the previous even number.
Change the 7 to
an
8 and watch the color get lighter
ye
t.
The following
program shows 128
co
lors and luminances:
NEW
1.9
REM
**
1.28
ATARI
COLORS
29
REM
**
1.6
COLORS
39
FOR
COLOR=9
TO
1.5
49
REM
**
8
LUMINANCES
59
FOR
LUMINANCE=O
TO
1.4
STEP
2
69
SETCOLOR
2
..
COLOR
..
LUMINANCE
65
PRINT
"COLOR="
;COLOR;"
LUMINANCE="
;LUMINANCE
79
REM
**
PAUSE
TO
SEE
COLOR
89
FOR
PAUSE=1.
TO
699:
NEXT
PAUSE
~9
NEXT
LUMINANCE
1.99
NEXT
COLOR
RUN
When the luminance reaches number
10
, the text disappears because
the default luminance of the text
is
also 10.
(The
default luminance
is
the luminance that the computer automatically uses unless it is
instructed to do otherwise.) Whenever the background luminance
is
the same
as
the text luminance, the text seems to disappear.
Pay
attention to background and text luminances
as
you work more with
color and luminance
in
graphics mode
O.
Type
GR.O
(which
is
an
abbreviation for graphics mode
0)
to
re
store the normal screen colors.
Change SETCOLOR 2 to SETCOLOR 4
in
line
60
and
run
the program
again. Because register 4 governs the border, the border changes
color this time instead of the background area. Type
GR.O
to restore
the
normal screen colors.
Graphics Modes 1 and 2
Graphics modes 1 and 2 provide large-size text and color options.
Graphics mode 2
is
identical to graphics mode 1 except that each
character
is
twice as tall. Mode 1 has
24
horizontal screen lines, and
mode 2 has
12.
To
enter graphics mode 1, type
NEW
1.9
GRAPHICS
1.
29
PRINT
1*6;"
GRAPHICS
MODE
ONE"
Run
the program. Graphics mode 1
is
in
orange text at the top of the
screen. At the bottom
is
a blue strip containing the word READY. The
blue strip
is
the text window and displays text
in
graphics mode
O.
Type
GR
.O to return to the
te
xt mode.
70
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