2. Binary Arithmetic

• Computers don't know the difference between signed and unsigned binary numbers.

• This is a good thing, because it makes logic circuits fast.

• This is also a bad thing, because distinguishing between signed and unsigned is our responsibility.

• The distinction is very important when detecting an overflow after addition or subtraction.

• Correct approach to detect the overflow is to consider two separate cases:

  1. Overflow when adding unsigned numbers.

  1. Overflow when adding signed numbers.