Unsigned Overflow Example

Assume 8 bit precision; ie. I can’t store any more than 8 bits for each number.

Lets add 255 + 1 = 256. The number 256 is OUTSIDE the range of 0 to 255! What happens during the addition?

255 = $ FF

+ 1 = $ 01------------------- 256 /= $00$F + 1 = 0, carry out$F + 1 (carry) + 0 = 0, carry outCarry out of MSB falls off end, No place to put it!!!Final answer is WRONG because could not store carry out.

/= means Not Equal

Previous slide

Next slide

Back to first slide

View graphic version