Column Reservation Numbers - Epson LQ-2550 User Manual

Option
Single-density
Double-density
High-speed double-density*
Quadruple-density*
CRT I
* Adjacent dots cannot be printed in this mode.

Column reservation numbers

The graphics command requires more than one number to specify how
many columns to reserve, since one line may use thousands of columns
but the printer does not use numbers larger than 255 in decimal.
Therefore, the graphics mode command uses two numbers for reserving
columns.
To figure nl and n2, divide the total number of columns by 256. The
quotient is rr.2; the remainder is nl. Since the command is set up for two
numbers, you must supply two even if you need only one. When you
need fewer than 256 columns, just make nl the number of columns you
are reserving and make n2 a zero.
For example, if you wish to send 1632 columns of graphics data, nl
should be 96 (the remainder) and rr.2 should be 6 (the quotient) because
1632 = (6 x 256) + 96.
The printer interprets the number of bytes determined by nl and rr2 as
graphics data, no matter what codes they are. This means that you must
be sure to supply enough bytes of graphics data or the printer will stop
and wait for more data and will seem to be locked. If, however, you
supply too much graphics data, the printer will interpret and print the
excess as regular text.
Using Software and Graphics
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