IBM Proprinter Emulation
58
Graphics
Graphics mode gives the user complete control over every dot position on the paper. Graphics may be
printed with various horizontal densities from 60 to 240 dpi, and a vertical density of 72 dpi.
Each byte of graphics data represents a vertical column of eight dots, with the MSB (most significant
bit) corresponding to the top wire of the print head. Turning a bit on causes a dot to be printed. The
bit values corresponding to each wire of the print head are shown below:
wire 1
128
(80 hex)
wire 2
64
(40 hex)
wire 3
32
(20 hex)
wire 4
16
(10 hex)
wire 5
8
(08 hex)
wire 6
4
(04 hex)
wire 7
2
(02 hex)
wire 8
1
(01 hex)
The appropriate bit values are added together to fire the desired wires. For example, a byte of graphics
data with the value 128 (80 hex) will fire the top wire, wire 1. A value of 192 (C0 hex) will fire the top
two wires, wires 1 and 2. A value of 11 (0B hex) will fire wires 5, 7 and 8.
Each graphics sequence contains two bytes (
n1
and
n2
) that specify how many bytes of graphics data
follow. The first byte,
n1
, can specify values up to 255. If that is sufficient, then
n2
is set to zero. For
values greater than 255,
n2
comes into play. The
n2
byte specifies multiples of 256. For example, to
specify 520 bytes of graphics data,
n1
= 8 and
n2
= 2. The bytes of graphics data are strung together to
create a graphics line that is eight dots high
,
and
n1
+ (
n2
x 256) dots long. Be sure to provide the
amount of graphics data that you specify, because the printer will not leave graphics mode until it has
accepted the specified number of data bytes.
If “Data Bits” is set to “7” in the interface setup menu, beware of potential problems in graphics mode.
Since the MSB (most significant bit) will always be turned off, it will not be possible to fire the top
wire of the print head. Worse yet, the value of
n1
or
n2
may be changed. For example, if
n1
specifies
200 bytes of data, and its MSB is turned off, the printer will only expect 72 bytes of data. It will exit
graphics mode, and then try to print the remaining 128 bytes of graphics data as normal text characters.
The result will surely not be pretty. To avoid such problems, the use of an 8-bit I/O interface for
printing graphics is highly recommended.
The normal graphics modes allow every dot to be printed. High speed graphics will print twice as fast,
but will not allow consecutive dots to be printed.
60 DPI Graphics
ESC K n1 n2 data
Selects eight wire single density (60 dpi) graphics for
n1
+ (
n2
x 256) columns of data.
Example: The following escape sequence will print six bytes of graphics data at 60 dpi. The resulting
figure will resemble a backslash character, “\”.
Escape Sequence:
ESC
K
6
0
128
64
32
16
8
4
Hexadecimal:
1B
4B
06
00
80
40
20
10
08
04
120 DPI Graphics
ESC L n1 n2 data
Selects eight wire double density (120 dpi) graphics for
n1
+ (
n2
x 256) columns data.
Example: The following escape sequence will print six bytes of graphics data at 120 dpi. The
resulting figure will resemble a backslash character, “\”.
Summary of Contents for FormsMaster 8000
Page 6: ......
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Page 89: ...DEC LA120 Emulation 83 VT Vertical Tab VTS Set Vertical Tab Stop...
Page 90: ......
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Page 140: ...ASCII Character Tables 134 Epson FX Fast Draft Epson FX Draft Epson FX Letter Quality...
Page 141: ...ASCII Character Tables 135 PC Fast Draft PC Draft PC Letter Quality...
Page 142: ...ASCII Character Tables 136 EBCDIC Fast Draft EBCDIC Draft EBCDIC Letter Quality...
Page 144: ...ASCII Character Tables 138 OCR A OCR B...
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