form products: paper, mailing labels, forms with holes punched down the side to fit
matching paper-pulling spikes on the printer. Judging speed in dot matrix printers can
be difficult. The ads talk of characters per second (CPS). Thirty CPS, for example,
amounts to 300 words per minute. But a 30-CPS printer will not necessarily turn out
300 words in 60 seconds. Most ads don't count the time required to move the carriage
head or advance the paper, or attend to other functions. The ads are calculating speed
in the "draft" mode, when the print head makes only one pass at each letter. For better-
looking type, usually called near-letter-quality, the print head makes multiple passes and
the output drops accordingly.
Figure 2-26 Dot matrix vs. letter-quality characters
(2) Daisy wheel printers. A daisy wheel is a flat disk with spokes, each
spoke having a single character embossed at the end. The daisy wheel makes an
image in much the same way as an electric typewriter. The wheel rotates to the desired
character, and is then struck by a hammer mechanism to form an image on paper.
Daisy wheels come in a variety of fonts (print styles and sizes) that can be
interchanged. They are noisy and slow, but produce very good no-graphics, high
legibility manuscripts or correspondence. The daisy wheel is superior to the dot matrix
in that it can produce high-quality type with a professional appearance. But, it cannot
produce graphics and it won't handle multitype styles and sizes. If you simply need
high print quality, you can meet this need for a cost of only about 0.
Figure 2-27. Daisy wheel.