Answer from cs61c-aw (wing hin kao 16500429) for Question 1
Since data can be anything - integers, floata, characters, instructions, etc, the data structure is not strong in type.
In the division and multiplication, we expect a 32 bit number, but sometime it would have a 31 bit integer.
so, in order to handle both signed integerd ans unsigned integers, we have several versions to deal with those instructions.
shifting is an important technique to solve these problems