IBM 6400 Series, Setup Manual

Page: 261 / 316

261
Printing Speed
The speed of text printing is measured in lines per minute (lpm). This speed is
dependent upon the number of dot rows required to produce a line of
characters, regardless of the number of characters in the line. Because more
dot rows are required to print lowercase characters with descenders, those
character lines will print at a fractionally lower rate.
In addition to character printing, the printer can plot dot–addressable graphic
images. The speed of graphics plotting is measured in inches per minute
(ipm). Unidirectional plotting can produce better print quality and takes about
twice as long as bidirectional plotting. You can select either plotting mode
from the operator panel or from the host computer.
Printing rates also vary according to the print quality you select. For example,
if you select the Near Letter Quality (NLQ) option, the printer uses more dot
rows and slower print strokes to form characters than if you choose the Draft
Quality option. Character formation and print speed are faster in Draft Quality
because the printer uses fewer dot rows to form characters.
Printing rates are listed in Appendix on page 257.