1.3. Program Status Word (PSW)

Try these first

1. 1.

   What does the Program Status Word (PSW) contain?

   Hint

   Think about the components that are necessary for the CPU's state.

2. 2.

   Define a conditional instruction.

   Hint

   Recall the if-then-else logic.

3. 3.

   What is the role of the Program Status Word (PSW) in CPU operations?

   • It only stores the last executed instruction.
   • It maintains the CPU's state and aids in decision-making.
   • It serves as a backup for old program states.

   Hint

   Think about why we need state information during program execution.

4. 4.

   True or False: The zero flag is set when the result of an operation is non-zero.

   • True
   • False

   Hint

   Recall what the zero flag indicates.

5. 5.

   You have a program that calculates the sum of two numbers. Detail how you would use flags to determine if you should output the result or skip to a different instruction.

   Hint

   Think about how the zero flag impacts decision-making in this context.

6. 6.

   Design a sequence of assembly instructions that demonstrates the use of the PSW during a function call and return.

   Hint

   Make sure to include steps that save and restore the state.