From what I understand from my lecture notes, overflow occurs when:
- $C_{in} \neq C_{out}$
- Change in sign
For $C_{in} \neq C_{out}$: suppose $111+111=1110=110$. In this case $C_{in}=0, C_{out}=1$, but consider a carry in then: $111+111+1=1111=111$ which according my the rules 1 above, is NOT overflow... so I suppose my understanding is wrong? If so how will I determine overflow systematically?
UPDATE
For those who are not sure what $C_{in}, C_{out}$ means and how to add/subtract binary, I hope the below working will help