cooperation with Messrs. ZEISS) in 1911. The development of 
automatically controlled instruments for the (continuous) 
drawing of curves began around i 960 [6]. 
Of special cartographic interest are above all the numerically 
controlled plotters. According to the form of the drawing base 
we differentiate between flatbed plotters and drum plotters , 
according to the type of the drawing between line plotters and 
raster plotters , and according to drive and control we distin 
guish plotters 
o with electromechanic incremental control 
o with electromechanic continuous path control 
o with electromagnetic continuous path control 
(Messrs. XYNETICS/USA and others) 
Of particular cartographic interest are furthermore the 
o electron-beam plotters 
(Messrs. PRAKLA-SEISMOS/Hannover, Messrs. CALCOMP/USA, 
and others). 
For special cartographic tasks are used 
o line printers 
(mainly "high-speed printers"). 
With high demands on the plotting accuracy and line quality, 
electromechanic flatbed plotters with continuous path control 
and light projection device (line drawing) are nowadays used 
(such as the Coragraph Plotter DC 3 of Messrs. CONTRAVES/ZUrich, 
and others). 
Highest plotting speeds are, however, reached with the electron- 
beam plotter . With the drum-raster-plotter KPU of Messrs.PRAKLA- 
SEISMOS/Hannover, for instance, a plotting area of 1 m x 1 m 
is exposed in about 5 minutes, a change of the beam intensity 
during the exposure of the film resulting in lb gray levels.