Commodore Plus 4 - Page 200

188 Programming Graphics
50 Start the y-coordinate of each column at zero.
60 Go through the eight available shades for each color.
70 Set the foreground color to the current color and shade.
80 Draw a box with the foreground color and fill it with color.
90 Adjust the y-coordinate for the next box.
100 Use the next luminance value.
110 Adjust the x-coordinate for the next column.
120 Use the next color value.
130 Change the foreground color to black and write "HIT KEY" on the screen.
140 Wait for a keypress and return to text mode.
Text Mode
The normal mode of the Plus/4's operation is text mode. In text mode, you can
PRINT alphanumeric and graphic characters onto the Plus/4 screen. When you
need to return to text mode after using another graphic mode, use
GRAPHIC 0.clear flag
The 0 tells the Plus/4 to return to text mode. The clear flag is an optional
parameter. If it is 1, the text screen is automatically cleared. If it is not present or is
0, any text previously placed on the text screen remains there. You can also return
to text mode by using the GRAPHICCLR command. This command also frees
the 12K reserved for the graphics screen for use by your program.
In text mode there are three possible color sources. The background and
border of the screen are colored with
COLOR 0, color, luminance
for the background, and
COLOR 4, color, luminance
for the border. The color of the characters themselves can be controlled with
COLOR 1, color, luminance