3.3. Conditional Instructions and Flags in Programming

Try these first

1. 1.

   What does the zero flag indicate?

   Hint

   Think about what happens when you add or subtract two identical numbers.

2. 2.

   What does the carry flag signify?

   Hint

   Consider what happens with the maximum possible value in binary.

3. 3.

   What does the carry flag indicate during arithmetic operations?

   • Indicates an overflow
   • Indicates a carry out
   • Indicates a negative result

   Hint

   Consider the implications of working with only the highest bit.

4. 4.

   True or False: An overflow flag being set always means the result is negative.

   • True
   • False

   Hint

   Think about the types of operations where overflow might occur.

5. 5.

   Consider two signed 4-bit binary numbers: 0111 (7) and 0001 (1). Perform the addition and analyze the flags set in the result.

   Hint

   Remember, how does the signed representation affect the outputs?

6. 6.

   Explain what would happen if you attempted to add binary numbers: 1000 (-8) and 1000 (-8) in 4-bit signed arithmetic.

   Hint

   Grid out the binary addition to visualize the carry and sign changes.