Displaying Characters on a Bit Mapped Screen—The CHAR
Command
So far, the example program has operated in standard bit map
mode. Bit map mode uses a completely different area of memory
to store the screen data than text mode (the mode in which you
enter programs and text). If you enter bit map mode, and try to
type characters onto the screen, nothing happens. This is
because the characters you are typing are being displayed on
the text screen and you are looking at the bit map screen.
Sometimes it is necessary to display characters on the bit map
screen, when you are creating and plotting charts and graphs.
The CHAR command is designed especially for this purpose. To
display standard characters on a bit map screen, use the CHAR
statement as follows:
220 CHAR 1,11,24,“GRAPHICS EXAMPLE”
This displays the text “GRAPHICS EXAMPLE” starting at line 25,
column 12. The CHAR command can also be used in text mode,
however it is primarily designed for the bit map screen.
Creating a Sample Graphics Program
So far, you have learned several graphics statements. Now tie the
program together and see how the statements work at the same
time. Here’s how the program looks now. The color statements in
lines 70,110,140,170,190 and 210 are added to display each
object in a different color.
6-12
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