Epson 8900 Series - Manual (Page 12)

Quality can be improved by increasing the dot density (resolution),
as shown in the following figure. Dot density is expressed in dots per
inch (dpi).
The Model 8900 Series Printer offers four levels of print quality,
based on the dot density and the placement of dots on the matrix.
The increased dot density at higher print-quality levels decreases the
print speed.
General Information 1-5
typical dot-matrix characters
effect of increasing dot density
low-resolution
character
medium-resolution
character
high-resolution
character