Commodore 16 User Manual page 38

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When you RUN this program, the screen background changes to a light
blue, and the spectrum of Commodore 16 colours is shown at each
luminance level. You'l notice that black is the same at all luminance
levels.
NOTE: Like most of the BASIC graphic terms reviewed in this
chapter. COLOR may be referred to as a statement or command
interchangeably
.
THE GRAPHIC COMMAND
The graphics you've seen so far use only the keyboard without really
taking advantage of your computers capabilities. The BASIC language
of your Commodore 16 contains commands to draw shapes and forms
through programs. To use the graphics-related commands of your
computer, you must enter a new mode, the GRAPHIC mode. Graphic
mode can be considered the drawing mode, since all the drawing
commands are "activated". You can't use these commands until you
specify exactly what graphics mode you want to use you specify
which type of graphics mode you want by using the GRAPHIC
command. There are three different modes: normal text, high-
resolution graphic and multi-colour graphic modes. With the
GRAPHIC command, you can even have part-text, pail-graphic screens
that !el you can write on one part of the screen and draw on the rest.
The command to enter this new mode is GRAPHIC.
In general tne GRAPHIC command looks like this:
GRAPHIC mode, clear :4-- this pail is optional
Mode number Effect
0 Text
1
High-resolution graphics
2 High-resolution graphics + text
3
Multi-colour graphics
4 Mullicolour graphics + text
Clear number Effect
0
Don't clear screen
1 Clear screen
To switch from the normal graphics (of text mode) to high-resolution,
just type the command GRAPHIC 2,1 and press
irrupt
The screen
goes blank and the cursor reappears near the bottom of the screen.
Your Commodore 16 screen is divided into 2 separate sections: the top
for graphics and the bottom five lines for text. If you don't want the
bottom live lines for text, you can use the command GRAPHIC 1,1,
but you won't be able to see any commands you type. You can switch
back and forth from graphics to text using the GRAPHIC command
The command GRAPHIC 0 switches the screen back to text, while
GRAPHIC 2 switches back to high-res without erasing the screen
Adding ,1 after the command erases the screen.
There is another way to clear the high-resolution screen. The
command SCNCLR erases the screen without changing the graphic
mode Once you use kgh-resolution graphics, the computer sets aside
10K of memory for your nigh-res screen, This memory is taken from
the BASIC program area. When you are through using graphics, you
can reclaim this memory by using the command GRAPHIC CLR.
HIGH RESOLUTION GRAPHICS
Your Commodore 16 screen contains 25 rows of 40 characters each,
or 1000 total character positions on the screen Each character is
formed out of single dots, with 8 rows of 8 dots each making an entire
character. Your screen has a total of 320 dots on each row, and 200
rows of dots. or 64.000 dots all together The high resolution graphics
on your Commodore 16 give you control over every single dot
Using normal graphics, you have limited control over the individual
dots. Drawing a racing stripe or a playing card is a nice little exercise,
but your creation is limited to using the characters (letters, graphic
symbols, etc.) on your computer keyboard. You can still create all
kinds of shapes and figures. but just a fraction of what you could do if
you could control each dot by itself. The high resolution graphics
capability of your Commodore 16 lets you do just that. Resolution
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