(3) Operations Console - The console consists of a 
position control (bowling ball), an Invac keyboard, a function 
switch panel, a stereoviewer reference viewer and correlation 
meter. 
  
a. Position Control - The position control unit 
provides the operator with a means of slewing or precisely 
moving any selected carriage in any direction. It consists of 
a bowling ball 4.47 inches in diameter which projects slightly 
above the table top. The ball 'floats" in a teflon ring. 
Friction between the ball and two rollers drive two (X and Y 
positioning) optical shaft encoders. The encoders transmit 
2-bit gray code electrical signals to the computer for assimilation. 
  
b. Invac Keyboard - This unit (Invac PK-1444) 
is a photoelectric keyboard and is used to communicate with the 
computer. No numerical data other than control codes are 
transferred to the computer through this device. It enables 
the operator to select the equipment components to be operated 
and the specific manner in which to control them as well as 
to select any of the modes in which the equipment is capable 
of operating. 
c. Function Switches = A function switch panel 
is provided to establish control links between the transport 
tables, computer and electronics circuits. 
  
d. Stereoviewer - The stereoviewer consists 
of two 4á-inch square faced CRTs, one above the other. The 
separated images are superimposed in a single plane using a 
combination of full and half-silvered mirrors. Stereoviewing 
is achieved by using cross-polariging filters at the CRT faces 
and in the viewing hood. An electronically generated floating 
mark is provided in both CRTs as a reference point. The mark 
is in the center of the viewed imagery. 
e. Reference Viewer - The reference viewer provides 
a 1:1 position indication of any table selected on the function 
switch panel. By inserting a photo in the reference viewer 
holder, the real time motion of any scanning table may be 
monitored. The unit consists of X and Y space rods linked by 
a teflon bearing block (also the reference light base) and 
driven by inexpensive ball-nut lead screws. 
  
f. Correlation Meter - The correlation meter is 
provided on the function-switch panel to indicate tracking 
errors with bias (null) or to provide a measure of the degree 
of correlation (peak). 
  
(4) Electronic Components and Power Supply Cabinets. 
a. Two Bay Electronic Cabinet - This unit provides 
basic storage for electronic components and contains provisions 
  
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