<hardware> A device that uses one or more pens that can be
raised, lowered and moved over the printing media to draw
graphics or text.
The heart of the plotter is the printer head assembly,
consisting of a horizontal bar and, attached to it, the head
assembly holding the pen in use. The pen can be positioned
horizontally by moving the pen assembly along the bar.
Vertical positioning is achieved by either moving the bar
(stationary page plotter) or the paper (rolling page plotter).
Combinations of horizontal and vertical movement are used to
draw arbitrary lines and curves in a single action, in
contrast to printers which usually scan horizontally across
the page.
Colour plots can be made by using more than one pen. Older
plotters required a separate pen for each colour and the pens
had to be changed by hand. Modern colour plotters usually use
only four pens (cyan, magenta, yellow, and black, see CMYK)
and need no human intervention to change them.
Monochromatic plotters have been largely phased out by laser
printers except when large paper size is needed, e.g. in
CAD.
