Epson LQ-510 User Manual page 117

An example will show how to specify n1 and n2. For instance, if you
wanted to redefine the characters A through Z, n1 would be A (or
ASCII code 65) and n2 would be Z (or ASCII code 90). So the
command ESC & 0 AZ (followed by the appropriate data) would
replace the entire alphabet of capital letters.
Following the specification of the range of characters to be defined
in this command are three data bytes, d0, d1, and d2, that specify the
width of the character and the space around it. The left space (in dot
columns) is specified by d0, and the right space is specified by d2.
The second byte, d1, specifies the number of columns of dots that
are printed to make up the character. By varying the width of the
character and the spaces around it, you can create proportional-
width characters that print at draft speed. The table below shows
the maximum values for these bytes.
Mode
Draft
Letter Quality 10 cpi
Letter Quality 12 cpi
Proportional
The last part of the command to define your characters is the actual
data that defines the dot patterns for each character. Since it takes
three bytes to specify all the dots in one vertical column, your
printer expects d1 x 3 bytes of data to follow d2.
User-defined Characters
d 1
9
29
23
37
Software and Graphics
d 0 + d 1 + d 2
12
3 6
30
42
4-25