2. A multiplication algorithm is an algorithm (or method)
to multiply two numbers. Depending on the size of the numbers,
different algorithms are in use. Efficient multiplication
algorithms have existed since the advent of the decimal system.
3. 1) instead of as many number of registers as there are bits in
multiplier, it is convenient to provide an adder for the summation
of only two successive binary numbers.
2)Instead of shifting the multiplicand to the left , the partial
product will be shifted to the right.
3) when the corresponding bit of multiplier is 0, there is no need
to add all zeros to the partial product.
EX:- 10011
X 11
10011
10011 shifting the bits of multiplicand left
OR
first right shift the partial product
10011 partial product is shifted to the left
10011
4.
5. The multiplicand is in register B and multiplier is in Q. The
SC is initially set a number equal to the number of bits in
multiplier.
The counter is decremented by 1 after forming each partial
product.
The sum of A and B forms a partial product which is
transferred to the EA register.
Both the partial product and multiplier are shifted to the
right. shrEAQ.
The LSB of A is shifted into MSB of Q, The bit from E is
shifted into MSB of A, and 0 is shifted into E.
In this manner the right most bit of the multiplier will be
the one which must be inspected next.
6.
7.
8. Booth's multiplication algorithm is a multiplication
algorithm that multiplies two signed binary numbers in two's
complement notation. The algorithm was invented by Andrew
Donald Booth in 1950
9.
10. Sign bits are not separated.
Qn designate the least significant bit of the mulltiplier
in register QR.
An extra flip flop Qn+1 is appended to QR to facilitate a
double bit inspection of the multiplier.
11.
12. AC, SC, Qn+1 are initialized by zero.
The two bits of the multiplier in Qn and Qn+1 are
inspected
If they are 10 subtraction of multiplicand from partial
product
01 addition of multiplicand in partial product.
When the two bits are same, partial product does not
change.
The next step is to shift right the partial product and
multiplier(including bit Q n+1).
This is an arithmetic right shift operation.
13. The arithmetic shift right leaves the sign bit
unchanged and shifts the number including the sign
bit to the right.
1 0 0 0 1 1 0 1
1 1 0 0 0 1 1 0
