|Marconi MkIII CCU and picture and waveform monitor|
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The Picture and Waveform Monitor (PWM) is the upper unit and the Camera Control Unit (CCU) is the lower one. The operating controls for the camera are on the front of the CCU along with the operators talkback controls. The small meter indicates the relative position of the graduated neutral density filter, the position of which is controlled by two microswitches that are operated by moving a small lever to the right at the bottom of the panel. The four small controls at the bottom would have been behind a door, similar to the one on the PWM above, but these are almost always missing now.