1. An apparatus comprising an ultrasound imaging system and a transducer probe assembly which is connectable to said ultrasound imaging system, wherein: said ultrasound imaging system comprises a multiplicity of channels and means for generating a first predetermined system identification signal indicating the number of said channels in said ultrasound imaging system; and said transducer probe assembly comprises: an array of ultrasound transducer elements the number of channels of said ultrasound imaging system being greater than the number of transducer elements of said array; means for multiplexing imaging data between said array of ultrasound transducer elements and said multiplicity of channels when said transducer probe assembly is connected to said ultrasound imaging system; means for storing first and second multiplexer state mappings, said first multiplexer state mapping consisting of a multiplicity of multiplexer states for multiplexing signals between said array of ultrasonic transducer elements and a first predetermined number of channels equal to the number of channels of said ultrasound imaging system and said second multiplexer state mapping consisting of a multiplicity of multiplexer states for multiplexing signals between said array of ultrasonic transducer elements and a second predetermined number of channels different than said first predetermined number; and logic control means for selectively configuring said multiplexing means in accordance with said first multiplexer state mapping in response to receipt of said first predetermined system identification signal from said ultrasound imaging system and in accordance with said second multiplexer state mapping in response to receipt of a second predetermined system identification signal different than said first predetermined system identification signal.