hi there, i'm a newbie and i would to ask about don't care in boolean function. how do we know it's a don't care? is all that is not listed in the ops and sop consider as don't care? help me please

 

"Don't Care" means that whether the input is HI or LO, the output will not change. Something like A OR NOT-A is a "Don't Care" function. No matter if A is HI or LO, the result will always be HI.

--Rich
Technically, it should be called a "Doesn't Care" circuit...

 

i see. thank you . but what if a question just gave a boolean function and was asked to determine the don't care. i was given a sum of product question and was asked to identify its don't care. may i know how?