56 
stereoplotting machine requires that the Operator, primarily 
concentrates On the interpretation of the image contents 
and the guidance of the fiducial mark. The interruption of 
stereoscopic viewing due to the necessary input of several 
characters via the alphanumeric keyboard must be reduced 
to & minimum, Therefore, the operator has got a double foot 
switch and & functional keyboard with 32 key buttons 
(Fig. 3). With the right foot switch the current model co- 
ordinates are stored in the counter interface. By actuating 
the left foot switch the function EXECUTE is additionally 
called up and a preset computer program is started which 
includes all points already recorded by the right foot 
switch into the calculation of a command sequence for the 
digital drawing table. The operator compiles the program 
from single commands of the plotting program. With these 
commands macros are formed and stored under a macro names 
One macro may consist of several command lines. In such 
a case, each EXECUTE processes one line, The cycle is re- 
started if all lines of a macro have been processed. 
A macro with the following sequence of commands 
PO 
D 
has for instance the effect that with the first actuation 
f the left foot switoh a polyson is drawn, the corner 
points of which were already recorded with the right or 
left foot switch. The operator can check the form drawn, 
set a new point and draw a parallel to this polygon through 
the new measuring point by another actuation of the left 
foot switch. The plotting computer is capable of storing 
a great number of macros. The frequently used macros are 
reasonably assigned to the key buttons 1 = 30 of the 
functional keyboard. The key buttons 31 and 32 are re- 
served for the functions VIEW (release of the drawing by 
the drawing head) and EXECUTE (corresponds to the left foot 
switch). 
The macro call-up is effected by pressing the respective 
key button. Thus the command memory is deleted and the new 
command sequence of the selected macro is entered, For less 
frequently used macros the call-up can be realized by 
writing the macro name on the display Key-board, The scope 
of delivery includes a standard set of macros which cor- 
responds to a standard assignment of the functional Kxey— 
boards The individual macros are symbolically represented 
on a pattern. 
5. Examples 
Figures 4 and 5 show examples of generated symbols and 
generated. line types. Then the symbol name is called up, 
the respective sequence of drawing commands is loaded 
into the RAM space of ihe drawing table control. Then the 
i _ 
te > 
symbol or the line type can be drawn as often as is desired. 
m