21.1.3. Instruction Fetch and Execution

Try these first

1. 1.

   What happens during the fetch phase?

   Hint

   Think about the first step in processing an instruction.

2. 2.

   What is the role of the micro-program counter?

   Hint

   Consider what directs the flow of instructions.

3. 3.

   What is the primary function of the micro-programmed control unit?

   • To execute programs directly
   • To generate control signals based on stored micro instructions
   • To store data temporarily

   Hint

   Think about the role of the MCU in the architecture.

4. 4.

   True or False: The fetch phase differs significantly between various instructions.

   • True
   • False

   Hint

   Consider what the fetch process aims to achieve.

5. 5.

   Consider a scenario where the micro-programmed control unit needs to handle an interrupt during instruction execution. How does it manage the current instruction state and ensure proper branching?

   Hint

   Think about preservation of execution context and how branching plays into handling exceptions.

6. 6.

   Design a memory layout scheme that preserves the integrity of control signals, branching conditions, and instruction operations in micro-program memory. Explain your design choices.

   Hint

   Reflect on the organization of data and what can cause conflicts during execution.