4. Assume a CPU with a fixed 36-bit instruction length has the following instruction format:

opcode [num-operands] [model operand1] [mode2 operand2] [mode3 operand3]

The opcode is the instruction. num-operands is 0-3 depending on the number of operands and

each operand has its own addressing mode specifier. Assume there are 150 instructions and 7

addressing modes. Answer the following questions.

a. If an instruction uses three registers, how many registers can be referenced?

b. If an instruction uses two registers and one immediate datum (in two's complement), what

is the largest immediate datum that can be referenced assuming there are 16 registers?

c. If an instruction has two operands, a register and a direct memory address, what is the

largest address (which is an unsigned binary number) if there are 64 registers?

d. If an instruction has two operands, both of which are memory addresses using base-

displacement mode where the base is a base register and there are 8 base registers, and the

displacement is an unsigned binary number, how long can the displacement be?

Remember, there are two separate base registers and two separate displacements.