3.2.3. The Importance of Context in Flag Usage

Try these first

1. 1.

   What happens when you add -5 and -3 in signed arithmetic using 4 bits?

   Hint

   Think about the sign bits.

2. 2.

   In unsigned arithmetic, how does adding 5 and 4 behave?

   Hint

   Check the upper limit for 4 bits.

3. 3.

   What does the overflow flag indicate?

   • Carry out of MSB
   • Invalid result due to overflow
   • Both A and B

   Hint

   Consider what happens when results don’t fit.

4. 4.

   True or False: The carry flag is generally significant in signed arithmetic.

   • True
   • False

   Hint

   Reflect on the role of the carry flag in signed operations.

5. 5.

   Analyze the addition of two 4-bit signed numbers: 0111 (+7) and 0001 (+1). What flags are set after the operation?

   Hint

   Consider max limits in signed numbers.

6. 6.

   Given two signed numbers -4 (1100 in binary) and +1 (0001 in binary), what are the results and flags after addition?

   Hint

   Focus on how negatives and positives interact.