Assume that PUSH and POP are two stack operations on a stack$-$oriented CPU. The top one or two stack components are always involved in arithmetic operations. Considering the initial state of an empty stack, show the elements in the stack after executing each instruction from the below code segment.

PUSH $9$

PUSH $3$

SUB

PUSH $12$

ADD

PUSH $10$

MUL

PUSH $5$

SUB

B$.$ Convert the above zero$-$address instruction program in a two$-$address instruction program. Calculate the number of bits required to execute the zero$-$address and two$-$address instruction format and justify the outcome.

Assume: The opcode uses $4$ bits, register address uses $8$ bits and memory address uses $16$ bits.