Abstract: A surgical system uses a single entry port in a wide variety of surgeries. To insert multiple surgical instruments into a patient through a single entry port requires that the shaft of at least one of the surgical instruments be bent between the base of the surgical instrument and the point where the shaft contacts a channel in an entry guide. Each surgical instrument is positioned by an instrument manipulator positioning system so that when the shaft is inserted in a channel of the entry guide, any bending of the shaft does not damage the surgical instrument and does not inhibit proper operation of the surgical instrument.

Abstract: An electronically reconfigurable digital pad attenuator is disclosed using selectively controlled segmented field effect transistors in a passive, non-gain state as the principal impedance elements. The attenuator may be fabricated in the monolithic microwave integrated circuit (MMIC) format with a segmented gate field effect transistor being connected in each of the separate branches of a Pi pad, Tee pad, or Bridged Tee pad attenuator configuration. The individual FET segments are maintained in a high admittance "ON" state or a low admittance "OFF" state in accordance with the binary control potentials applied to the gate of each segment, the principal electrodes being maintained at a zero potential difference. The attenuation then becomes a function of the binary gate potentials applied to each segment and assumes one of a set of well-defined discrete values. The attenuator consumes minimum power, provides attenuation steps that are independent of GaAs MMIC fabrication process tolerances, i.e.