In one example, a system comprises a vector-by-matrix multiplication array comprising non-volatile memory cells organized into rows and columns; a plurality of word lines coupled respectively to rows of the vector-by-matrix multiplication array; and a word line driver coupled to the plurality of word lines, the word line driver comprising a plurality of select transistors coupled to a common control line and the plurality of word lines, and a plurality of bias transistors coupled to the plurality of select transistors and capable of providing a bias voltage to a single select transistor in the plurality of select transistors or to all of plurality of select transistors in response to control signals.