Commodore Plus 4 - Page 204

198 Programming Graphics
100 In the thirteenth column, print a reversed space, 13 cursor rights, and
another reversed space.
110 Do next line.
120 On the fifteenth line in the thirteenth column print 15 reversed spaces.
130 Print three cursor down commands.
140 Print a color change to black, space over, and print HIT KEY.
150 Wait for a key. Then change background and border colors to normal
values.
High-Resolution Mode
The graphics mode that provides maximum resolution on the Plus/4 is accessed
with the command:
GRAPHIC 1 filear flag
The clear flag is optional (1 clears the high-resolution screen, 0 or absence leaves
the screen intact).
This statement creates a bit-mapped screen on which the programmer can use
the Plus/4's graphics statements: BOX, CIRCLE, DRAW, and PAINT. A
section of memory (12K bytes) is set aside for this use and is therefore not
available for the BASIC program. The text screen area of memory is left intact.
Therefore, you can PRINT on the text screen behind the graphics screen, and the
PRINTed data are revealed when you return to text mode.
The Split-Screen You can create the bit map and view the upper portion of it
and the lower five lines of the text screen simultaneously with the command:
GRAPHIC 2,clearflag
Again, both the text and the bit-map areas of memory are reserved. The use of
this statement merely reveals the lower five lines of the text screen and conceals
the corresponding portion of the bit map. When the clear flag is set to 1, both the
graphics and text screens are cleared and the text cursor is placed at the left of the
first visible text line.
The Coordinate System The high-resolution screen is normally addressed with
a 320 by 200 coordinate matrix. The horizontal (or x) coordinate ranges from 0 at