Construct a CPU which has only three instructions: LDI, LD and ST$.$ The instructions will

have the same format with the ones in the Reptile$-4$ instruction set. Your design must be

MINIMAL, ie$,$ you shouldn't use any unnecessary elements.

a$)(20$ Pts$)$ Draw the hardware circuit for this CPU without the control unit. Indicate all the

necessary control signals in your drawing. Use the same level of detail as used in the class, ie

you don't need to show the internals of ALU, register banks, memory, multiplexers etc. if you

use any of these.

b$)(20$ Pts$)$ Draw the control unit for this CPU. Write down the microcode in binary. Indicate

which column of the microcode belongs to which signals.

Note: Such a CPU will not have any value for practical purposes.