Graph plotters are used to produce high quality precision graphics usually on large sheets
of paper.
They are slow, but can draw continuous curves often in a variety of colours. They are
especially useful for architectural drawings, building plans and
CAD (Computer Aided Design) applications, where precision
drawing is required.
A mechanical arm holds a pen which can be moved
across the page. The paper is sometimes laid on a flat bed
(flat bed plotter) or on a rotating drum (drum plotter).

drum [drʌm]

n. 鼓,鼓声

v. 击鼓,作鼓声