Double-Density Plot Mode; Horizontal Graphics - Double Density - Texas Instruments 880 User Manual

•
6.2.2 Horizontal Raster Data Format/
Double-Density Plot Mode
In double-density plot mode (Figure 6-2), data
lines containing the ENQ (>05) control character
provide the even dot location pattern, and data
lines containing the EOT
(>04)
control character
provide the odd dot location pattern of the hori-
zontal raster graphic. To print a double-density
plot for any given line of data, a line of odd dot
location pattern must be entered before a line of
even dot location pattern. Both dot patterns are
then merged to create a double-density row of
dots printed at half the speed of the single density
plot.
Either of two line termination characters cause the
Model 880 to start printing. Each line termination
character that follows a row of data initiates the
DATA INPUT (HEX): 7E 60 74
04 OA
4A 4D 7C
05
OA
7E
=
0 1 11 1 1 1 1 01
60
=
0
4A
=
0 1 10 0 1 0 1 01
4D
0
PRINTED OUTPUT:
LEFT
MARGIN
111 0
11 0 0
1st
BYTE LSB 2nd BYTE LSB
II'
Ji'
1
2 3 4
5
6
1
2 3 4
•
•
*
#
•
#
*
# • # • #
*
• •
• * • *
•
•
• • • • • • • • • • • • •
• • • •
*
=
EVEN DOT LOCATION
#
=
ODD DOT LOCATION
printing of the partial plot data. The line feed char-
acter, LF (>OA), causes the line to print and the
paper to move up nine dots. The form feed char-
acter, 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.
In this plot mode, bytes that are outside the right
margin are discarded.
When more than one odd dot pattern is received,
data is saved in the same row until terminated, or
an even pattern is entered.
Figure 6-2 shows a double-density plot of horizon-
tal raster data.
0 0 0 01
74
=
0 111 1 0 1 0 01
1 1 0 11
7C
0 111 1 1 1 0 01
3rd BYTE LSB
II' 5
6
1
2 3 4
5
6
• • • •
# •
• •
• *
#
* • * • *
#
• • • • • •
•
• •
•
•
•
•
• • • •
2222627-29
Figure 6-2.
Horizontal Graphics - Double Density
6-5