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Printing
With
Dot Gmphics
650
DATA 56,56,56,12~,12~,24~,24$3,224,224,192
660
DATA
128,0,0,0,0,0,0,0,0,0
147
Plotting
with
Radix
This section
of the manual
gets into more serious
BASIC
pro-
gramming
just because
it's required
in order to have the computer
act as a plotter
driver.
Don't be intimidated;
while it's beyond
the
scope of this manual
to teach BASIC,
if you try the examples
and
take it slowly
you should
be doing
some fancy
plotting
of your
own before
you know it.
If designing
and calculating
dot graphics
images
by laying
them out on graph paper
seems
too tedious
to you, then let the
computer
do the work
for you! With your computer
doing the
calculations
and Radix plotting
the output, you can come up with
some terrific
business
graphs,
charts,
and mathematical
function
plots.
The best way to do this is to set up an array in memory.
This is
your "graph paper."
The first thing to do is to determine
how big
you want your output to be; this will determine
the size of your
array. (If you have grandiose
plans to fill an entire page with plot-
ter output, you better have lots of memory
in your computer.
With
60
dots per inch horizontally
and
72
dots per inch vertically,
it
takes at least
540
bytes of memory
for each square inch of plotted
area.
That
doesn't
sound
so bad-but
an area
8 inches
square
requires
over 32K!)
Your array should be two-dimensional
(just like graph paper)
where
one dimension
will be the number
of columns
of dots and
the other dimension
is the number
of printing
lines (remember
that you can have up to eight rows of dots per printed
line).
Here's
a program
that will use calculated-shape
graphics
to
plot a circle.
As you'll see, by changing
a few lines it can be used to
plot virtually
any shape.
10 I General purpose RADIX plotting program.
20
'
30
'Set program constants.
40
MAXCOLI =
75
: MAXROW% = 14
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