Figure 1-22.External hard disk drive with removable disk
Most printers you are likely to use while working on
microcomputers are the low-speed varieties. They are
able to print text at rates of 200 to 800 characters per
second and usually output this information one
character-at-a-time. After close examination, you will
find that basically the only major difference between
printers designed for micros and those used on larger
mainframes is their size, and the speed at which they
print. Other than that, they are very much alike in terms
of setup, operation, and operational features.
Micro printers, like mainframe printers, are either
impact or nonimpact. At least six printing technologies
are used to produce hundreds of microcomputer printer
models. These technologies include dot-matrix (which
forms characters using a series of dots), xerographic,
electrostatic, ink jet, and laser.
DOT-MATRIX PRINTER. The dot-matrix
printer uses a print head made up of pins. It creates the
characters by using these pins to generate characters a
dot-at-a-time. Dot-matrix printers have speeds that
range from 60 to 350 cps.
XEROGRAPHIC PRINTERS. Xerographic
printers use a printing technique very similar to the
methods used in duplicating or copying machines. The
printers can operate at speeds up to 4,000 lines per
ELECTROSTATIC PRINTERS. Electrostatic
printers use a special photographic paper that allows
characters to be etched onto the paper using a stylus.
The stylus, made up of tiny wires, forms characters by
placing an electrostatic charged image on the paper.
Then, as the paper is moved through a toner solution
containing ink particles, the ink adheres to the charges
that form a pattern on the paper to develop the character.
This type of printer can be used for both printing and
plotting (displaying graphic output), and can print up to
5,000 lines per minute.
INK JET PRINTERS. Ink jet printers employ a
technique very similar to the way we use a can of spray
paint and a stencil. A spray of electrically charged ink is
shot (under pressure) toward the paper. Before reaching
the paper, the ink is passed through an electrical field,
which forms the letters in a matrix form. The print
resulting from this process consists of easy to read,
high-quality characters. Some manufacturers use large
droplets of ink for faster printing, while others use small
droplets for better clarity but with slightly reduced
printing speeds. This type of printer can print up to 300
characters per second.
LASER PRINTERS. Laser printers direct a
beam of light through a rotating disk containing the full
range of print characters.
The appropriate character
image is directed onto photographic paper, which is
then put through a toner, developed, and used to make
additional copies. The print resulting from this process
consists of sharp, clean images that are easy on the eyes.
These printers can print up to 20,000 plus lines per
Many micro printers can print subscripts and
superscripts, print in several different colors, print
graphic material, and output text in several different
type styles (fonts).
Some printers print in a single direction only, like
the conventional typewriter, whereas others print in
both directions (bidirectional) to save on time-
consuming carriage returns. Many come with either a
friction feed (for handling single-sheet paper) or an
adjustable tractor feed (for handling continuous forms),
and some even have both.
You can initiate a wide range of printer functions
either through the applications program you are
working with or by using the controls located on the
front of the printers operating panel. These controls can
be buttons, lights, and switches. With a simple touch of
a button, you can change such things as type style, letter
quality, pitch, and spacing. Its that simple.
As mentioned, most printers are equipped with an
operating control panel that allows you to change
For example, you can change the
number of characters per line or lines per inch, change
fonts and type size, and switch from draft to letter-
You can choose any combination of