Suppose we want to add two n-bit binary numbers, X and Y . Modify the serial add
ID: 3761909 • Letter: S
Question
Suppose we want to add two n-bit binary numbers, X and Y . Modify the serial adder circuit discussed in lecture and shown in figure, so that it produces an overflow output, V. When bits xn?1 and yn?1 are the input to the serial adder V = 1 if the addition has caused overflow else V = 0 at this clock time. V is a don’t care, when bits 0, 1 . . . n ? 2 are the inputs to the serial adder.
(a) Assume X and Y are unsigned positive numbers.
(b) Assume X and Y are two’s complement numbers.
+ 1 x. Full Adder y1 CK- Clock (b) Truth table (a) With D flip-flopExplanation / Answer
you can use the same circuit which is used for full adder as it is.
only thing you have to use is pass the Cn as V
because if the last addition of the full adder is generating carry , it will not be added to input again
this carry will be dicarted, which means that , overflow occured
hence V=Cn