As
you
may
recall
from
Chapter
2,
the
print
head consists
of
nine
pins stacked
one
above the other.
The
print
head can therefore
print
columns
of
up
to nine dots at a time.
For
most
graphics applications
however, the
bottom
pin
in
the
print
head
is
not
used because
most
computers
send data
to
their
printer in
eight-bit
"bytes".
This
is
the
most
commonly
used
system
for
dot
graphics,
known
as
"eight-
pin
dot
graphics."
Another
form
of
graphics, seven-pin
dot
graphics, uses only seven
of
the nine pins
on
the
print
head.
This
is
the
form
of
graphics used
on
older
Commodore
printers such
as
the
MPS
801
and
MPS
803.
There
are
many
commercial
programs,
books
and magazine arti-
cles
which
use and explain seven-pin graphics.
The
MPS
1200 can
handle seven-pin
as
well
as
eight-pin
graphics. Seven-pin graphics
is
covered in detail
in
Chapter
7.
You
can also use all nine pins
on
the
MPS
1200
print
head for
graphics.
Nine-pin
graphics is quicker than using
eight-
or
seven-
pin,
but
is a
bit
more
difficult to code.
7-Pin 8-Pin 9-Pin
128
•
128
•
64
•
64
•
1
•
32
•
32
•
2
•
16
•
16
•
4
•
8
•
16
•
32
•
8
•
8
•
'\
4
•
4
•
2
•
2
•
1
•
1
•
64
•
+ 128
Not used
•
128.
chr$()chr$( )
~
128-9-pin ON
0-9-pin OFF
Figure 6-1.
Dot
Graphics
Pin
Comparison
As
you
can see in Figure 6-1, the pin
numbers
are reversed in
Commodore
seven-pin graphics.
To
avoid confusion due to this
difference
and
since
Commodore
mode
uses this type
of
dot
graph-
ics exclusively, it is covered in a separate chapter.
6-2
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