(Word Problem) Your task is to design the control for a sequential 4-bit multiplier. The data path is shown in Figure Ex. 10.5. It consists of a 4-bit adder, a 4-bit register, and a 9-bit shift register. The latter shifts right when its Sh input is asserted (assume that zeros are entered at the left for this operation). A new value is loaded into the high-order 5 bits of the shift register when Ld is asserted. The same 5 bits are zeroed when Cl is asserted. These signals are synchronous.

 

(Hint: As a simple example, consider the 2-bit version of the device forming the product of 11₂ and 10₂.)

 

Draw a Mealy machine state diagram for a 4-bit multiplier. The inputs are S (a multiply start signal) and M (the low-order bit of the multiplier). The outputs are the Sh, Ld, and Cl signals