OUTPUT computer disc unit (HP disc 1200K words) 
drafting table (Gerber 32 table) having screw 
gear drive in both axes 
light beam drafting head (Gerber Optical 
Exposure Head OEH-B) 
In the two years since installation of our system: 
the 4 stereo instruments have been working 2 shifts 
of 15 hours per diem 
the ADM has logged over 7500 hours which equates 
to 14 - 15 hours daily: 
17% edit mode 
69% drafting mode 
7- 8% research and development 
6 - 7% maintenance and installation. 
For our production '"today'" we put the input topographic information 
through two passes: 
PASS 1 an edit pass where the data is taken from the input tapes: 
the physical errors are removed from the tape through 
an auxiliary 1K buffer on the Gerber M12 
the input data is checked for compatibility and human 
errors are removed, i.e. mistakes and blunders 
the input is computed i.e. square-up buildings, etc. 
the input is blocked out on the disc and then the edited 
input is transferred onto 9-track magnetic tape - 800 bpi.