Answer each of the following questions making use of the above diagram of the HACK CPU

$1.$ Specify the control logic for the input indicated by the dashed circle containing $1.$ Use basic gates and specify the inputs in terms of the bits on the instruction bus.

$2.$ Explain the rationale for the MUX indicated by the dashed circle containing $2.$

Answer the following questions with a short response

$3.$ The HACK assembler needs to make two passes through an assembly program before converting it to the HACK machine language. What is done on the first pass?