1. Question 8.18 (page 397)
Design a digital system that multiplies two unsigned binary numbers by the repeated addition method. For example, to multiply 5 by 4, the digital system adds the multiplicand four times: = 20. Let the multiplicand be in the register BR, the multiplier in register AR, and the product in register PR. An adder circuit adds the contents of BR to PR, and AR is down-counter. A zero detection circuit Z checks when AR becomes zero after each time that it is decremented. Design the control by the flip-flop per state method.

2. Tips : Start = 0 Z = 0 Start = 1 A B C Z = 1
Note : A, B, C – D flip-flops
Z = 1
A : Initial state
B : BR Input A
AR Input B PR
C : PR BR + PR
AR AR - 1 n LD BR LD n AR
DEC n
ADD 2n 2n
Zero Z
CLR PR LD

3. Answer : Q8-18 START LD_BR = LD_AR = CLR_PR LD_PR = DEC_AR Z B A C D D
CLK
RESET