serial or parallel interface. Among these, the RS-232 in
the most common serial interface and the Centronics
parallel interface is the most common parallel interface.
CONTROL SECTION The control section of a
printer receives data from the interface section, decodes
the data to determine whether it is a control word or data
to be printed. The control section will then take the
CONTROL PANEL The control panel lets the
operator set some of the operating parameters of the
printer and paper.
PAPER-FEED ASSEMBLIES The paper-feed
assemblies move the paper through the printer. Tractor
feed and friction feed are two main types of paper feed.
POWER SUPPLY The printers power supply
converts the ac line voltage to the required voltages for
the printer to operate.
IMPACT PRINTERS Impact printers form the
characters by striking a device, such as a print hammer
or print wire, against an inked ribbon and the paper.
LINE PRINTERS Line printers are capable of
printing at high speeds. They use rotating print drums,
print chains, and print bands with raised character dyes
to print characters. Character sets with these printers
are limited to the characters on the drum, chain, or band.
CHARACTER PRINTERS Character printers
print one letter or character at a time. Two of the more
common character printers are the dot matrix printer
and the daisy wheel printer. The dot matrix forms
characters using a series of print wires. The daisywheel
printer uses a small plastic wheel with the character
dyes on the spokes of the wheel.
NONIMPACT PRINTERS Nonimpact printers
use methods other than striking the paper through an
LASER PRINTERS Laser printers are a type of
electrostatic printer that produce a very high resolution
output. The laser printer uses a laser diode to form the
image to be printed on a charged photosensitive drum.
ELECTROTHERMAL PRINTERS Elec-
trothermal printers form characters on a special heat
sensitive paper. Small heaters are activated to form the
characters, and the heat causes the paper to change
INK JET PRINTERS Ink jet printers use a fine
spray of ink to paint characters on paper.