6.2
HORIZONTAL
RASTER
GRAPHICS
Horizontal graphics data
can
be
printed at a den-
sity
of
60
dots per inch, single density plot mode,
or
120
dots per inch, double-density plot mode.
The vertical density
is
144
dots per inch.
6.2.1
Horizontal
Raster
Data
Format/Single-
Density
Plot
Mode
In single-density plot mode (Figure 6-1), a line
of
data containing the control character ENQ (>05,
or
hexadecimal 05), indicates that data from the
left margin
is
horizontal raster data.
Bit 7
of
all graphics data bytes must
be
set
(1)
for
the data
to
be treated
as
graphics data; that is,
valid characters
for
graphics data are from >40
to
>7F. The
low
6 bits are plot data.
The least significant bit (bit
1)
is
plotted
at
the
left
on the paper, and the remaining plot data bits (2,
3, 4, 5, and
6)
are plotted,
in
order,
to
the right
of
bit
1.
A line feed (>OA) ends a
row
of
data bits and the
next byte
of
graphics data contains the first six
plot data bits
to
appear on the next row. When the
printer
has
stored nine rows,
it
prints all
of
them
and moves the paper up nine rows
so
that the
tenth row
of
dots
will just touch the ninth row.
When a
row
of
raster data
is
longer than the line
width,
extra characters
are
discarded.
Line termination characters
LF
and
FF
cause the
Model
880
Printer
to
start printing.
Two
or more
consecutive
line feeds,
LF
(>OA), cause the line
to
be
printed and the paper
to
be
moved at the
current vertical pitch. A single
line feed does
not
cause printing unless the last data received was
for the ninth print row. A form feed,
FF
(>OC),
causes the line
to
print and the paper
to
move
to
the top
of
the next form. The carriage return,
CR
(>00),
causes no printing or paper motion
but
allows the
row
of
data
to
be
changed by the next
data
line received.
When a data
line does
not
contain the graphics
data character, the remainder
of
the rows
are
filled
with
"blanks"
(>40), and the line
is
printed. The
printer
is
now
back
in
the character print mode,
and the paper
is
moved for the next line
of
the cur-
rent vertical pitch.
GRAPHICS
DATA
BYTE
6-4
M~B
-~-I-;:-
-5- -4-
-3-
-2-
Ysl
DATA
INPUT (HEX): 4A
4D
7C
05
OA
7E
40
05
OA
4A
~
0
,
10
0
7E
~
0
,1,
,
PRINTED OUTPUT:
LEFT
MARGIN
,
,
o ,
01
4D
~
0
, ,
01
40
~
0
PLOT
DATA
+
o ,
,
o
,1
7C
~
0
+
000
o
01
,1,
,
'st
BYTE
LSB
2nd BYTE
LSB
3rd BYTE
LSB
'"
'"
'"
1 2
4
6 1
3 4
6 1 2
4
• * •
* • *
••
• • * • * • * • * • * •
,
Figure 6-1.
Horizontal
Graphics
-
Single
Density
, 0
01
2222627·28
..
To Next Page
Loading...