Epson LQ-860 - Impact Printer, User Manual

Page: 118 / 325

By adding the appropriate label numbers together, you
can
fire any
combination of pins. Below are three examples of how to calculate
the number
that
will fire a particular pattern of pins.
With this numbering system, any combination of the eight pins adds
up to a decimal number between 0 and 255, and
no
numbers are
duplicated.
Because there are 24 pins in each column, you must make a
calculation for each of the three sections in each column. As you can
see, this method of planning and printing dot graphics requires
considerable calculation. Because triple-density uses 180 columns
per inch, printing a single line of triple-density graphics only one
inch long requires 540 numbers. Fortunately, commercial graphics
software is available to do these calculations for you.
Before you can put these numbers into a graphics program,
however, you need to know the format of the graphics command.
The Graphics Command
The graphics mode command is quite different from the other
commands used by the printer. For most of the other printer modes,
such as emphasized and double-wide, one command turns the
mode on and another turns it off. For graphics, the command is
more complicated because the code that turns on a graphics mode
also specifies how many columns it will use. After the printer
receives this code, it interprets the numbers that follow as pin
patterns and prints them on the paper.
Software and Graphics 4-11