28. 28. The memory unit of a computer has 256K words of 32 bits each. The computer has an instruction format with four fields: an opcode field; a mode field to specify one of seven addressing modes;

a register address field to specify one of 60 registers; and a memory address field. Assume an instruction is 32 bits long. Answer the following:

1.

a) How large must the mode field be?

2.

b) How large must the register field be?

3.

c) How large must the address field be?

4.

d) How large is the opcode field?