2-Bit 2s Complement Adder

Now you will do 2s complement addition. Remember that the carry out DOES NOT mean that you have an error. 

You need to compare the left hand digits and see if there is an overflow. So you will now have 4 inputs and 2 outputs. Since this is  2s complement, to check the "overflow" flag you need the "complex" check on the left most bits. We will not be doing that here.