IBM 6400-D Generation II Series, Setup Manual

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Appendix B
Printing Speed
Serial matrix printers use a moving printhead with pins to form single
characters sequentially along the printed line. Unlike serial matrix printers,
line matrix printers divide every printable line into horizontal dot rows, then
print a dot row of the entire line at every lateral sweep of the shuttle. The IBM
6400-D Series is a line matrix printer.
During each sweep of the shuttle, hammers are activated to print dots at the
required positions in the dot row. When the shuttle reaches the end of a
sweep, it reverses direction, and the paper advances one dot row. The
hammers print the next row of dots as the shuttle sweeps in the opposite
direction, as shown in Figure 71, unless unidirectional printing is chosen.
After a line of characters is printed, the paper advances to the first dot row of
the next print line. This creates a number of blank rows between lines of
characters, depending on the print mode and line spacing you selected.
Figure 71. Line Matrix Printing
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.
Paper
1
2
3
4
5
6
7
8
9
10
11
12
1
2
*
* *
*
* *
Feed
Direction of shuttle movement
Paper
Advances
Paper
Advances
Space
Start
Dot
Row
Character
Line
1 Hammer
Print Span 1 Hammer
Print Span
Used for lowercase descender only
Used for underline and lowercase descender