Posted by cadet1620 on URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/4-Way-16-Bit-MUX-Problem-tp4025121p4025123.html
bickinator wrote
Never mind I figured it out. I thought the selector bits were ordered differently in the array.
Wires on buses are numbered like bits in registers -- 0 through N-1 starting from the right. This way bit i in the register and wire i on the bus are the 2i weighted bit in the binary value in the register.