Answer
See explanation
Work Step by Step
Since the instruction size is double the size of MDR it will take two cycles to bring the complete instruction to the CPU hence von Neumann cycle should be updated so that program counter is updated after the instruction is completely received by the CPU.
In a standard Von Neumann architecture, the fetch phase retrieves one full instruction from memory into the MDR. But with a 16-bit MDR and 32-bit instructions, the system must split the fetch into two steps:
1. First Fetch
- The Program Counter (PC) points to the memory address of the instruction.
- The CPU fetches the first 16 bits of the 32-bit instruction into the MDR.
2. Second Fetch
- The PC is incremented (or a temporary register is used) to point to the next memory address.
- The CPU fetches the remaining 16 bits of the instruction into the MDR.
3. Instruction Assembly
- The two 16-bit halves are combined (usually in an Instruction Register or buffer) to form the full 32-bit instruction.
- Execution proceeds as normal.
