You are asked to design a 2-bit unsigned binary multiplier. The multiplier takes
ID: 3833943 • Letter: Y
Question
You are asked to design a 2-bit unsigned binary multiplier.
The multiplier takes two 2-bit inputs, A[1:0] and B[1:0], and produces an output Y[n-1:0]
which is the product of these two numbers:
Y[n-1:0] = A[1:0] * B[1:0]
a. (1 point) What is the maximum value that can be represented by one of the inputs?
b. (1 point) What is the maximum value that Y will ever have?
c. (1 point) What is the value of n, the number of output bits?
d. (8 points) Construct the complete truth table for the multiplier: you will have four inputs: (A[1], A[0], B[1]
and B[0]), and n outputs
e.Extract from the table the boolean expression for bit 1 of the output (considering, as always bit
as the lsb), simplify it to the extent possible, and draw the corresponding logic circuit.
Explanation / Answer
a) Both the inputs are of two bit so maximum value is 11 in binary and 3 in decimal.
b) When both the inputs have maximun value only then output is maximum so maximum output value is 1001 in binary and 9 in decimal.
c) Value of n is 4 . The maximum output is 1001 so it use 4 bits.
d) Truth table :
*****INPUT1**************** *********INPUT2************ ********************OUTPUT******************************
A[1]
A[0]
B[1]
B[0]
Y[3]
Y[2]
Y[1]
Y[0]
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
1
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
1
0
0
0
1
0
1
1
0
0
0
1
0
0
1
1
1
0
0
1
1
1
0
0
0
0
0
0
0
1
0
0
1
0
0
1
0
1
0
1
0
0
1
0
0
1
0
1
1
0
1
1
0
1
1
0
0
0
0
0
0
1
1
0
1
0
0
1
1
1
1
1
0
0
1
1
0
1
1
1
1
1
0
0
1
A[1]
A[0]
B[1]
B[0]
Y[3]
Y[2]
Y[1]
Y[0]
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
1
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
1
0
0
0
1
0
1
1
0
0
0
1
0
0
1
1
1
0
0
1
1
1
0
0
0
0
0
0
0
1
0
0
1
0
0
1
0
1
0
1
0
0
1
0
0
1
0
1
1
0
1
1
0
1
1
0
0
0
0
0
0
1
1
0
1
0
0
1
1
1
1
1
0
0
1
1
0
1
1
1
1
1
0
0
1
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