Calculated Shapes
(Plotting)
Another
way
to ease the task
of
defining graphic shapes
is
to let
your
computer
design the shapes for you. This
is
how
computer
plotters
work,
and
your
MPS
1200 can function
as
a plotter too.
Any
shape
that
can be defined
by
a mathematical equation can be
calculated
and
plotted
on
the
MPS
1200.
Plotting
calculated shapes generally requires
some
fairly advanced
programming
skills,
which
are
beyond
the scope
of
this manual.
To
get
started,
however,
we'll
describe
some
general
programming
approaches
and
show
you
one
program
that produces a shape
we
call a
"squiggle."
Plotting
programs
set aside a
part
of
the
computer's
memory
to
store the dots
you
want
to
print.
In
computer
terms, that means
setting
up
an array.
In
effect, the array is the
computer's
"graph
paper. "
The
first thing to
do
in
setting up an array
is
to define
size-called
"dimensioning
the
array."
Like
graph
paper, the array
must
have
two
dimensions.
One
is the horizontal dimension (the
number
of
columns
of
dots), and the
other
is
the vertical dimension (the
number
of
printing
lines).
As
with
defined shapes, the
next
step is to
mark
which
dots are to
be
printed.
This
is
done
by
the
program.
As it calculates the shape,
it
changes the values in the appropriate array locations
from
zero to
the necessary pin
numbers.
When
all the points
in
the shape have been calculated
and
their pin
numbers
stored
in the array, the final step prints the array
on
the
MPS
1200.
Aside
from
the
programming
required,
two
other
limiting factors
with
calculated shapes are the
memory
size
and
the processing
speed
of
your
computer.
Arrays use
up
computer
memory
very
quickly.
For
example, in single density, a
one
inch square contains
4,320
dot
positions.
Using
8 dots per
column,
that
is
540 array
locations.
That
may
not
sound
like a lot,
but
since each array
location requires at least
two
bytes
of
memory,
this one-inch
square uses
up
over
1K
of
memory.
To
plot
an 8 x 8-inch
square-
less than
one
page-you'll
need
over
64K
of
memory
just
for the
array!
6-14
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