Understanding Memory Access by CPU
In a computer system, different types of memory serve various purposes, and the CPU interacts with them in specific ways. Among these, the distinction between direct and indirect memory access is crucial.
Types of Memory
- RAM (Random Access Memory):
- Directly accessed by the CPU.
- Volatile memory used for temporary data storage while programs are running.
- Cache Memory:
- A smaller, faster type of volatile memory.
- Used to store frequently accessed data for quick retrieval by the CPU.
- ROM (Read-Only Memory):
- Non-volatile memory that retains data even when the power is off.
- Contains firmware and system-level instructions; the CPU can access it directly.
- Memory Card:
- External storage used for additional data storage.
- Typically accessed through interfaces like USB or card readers, not directly by the CPU.
Why Memory Card Cannot Be Accessed Directly by CPU
- External Interface:
- Memory cards (such as SD cards) utilize external interfaces that require additional hardware like controllers to communicate with the CPU.
- Data Transfer:
- The CPU relies on device drivers and operating systems to facilitate data transfer between the memory card and RAM.
- Speed and Efficiency:
- Direct access is reserved for faster memory types (like RAM and Cache) to ensure efficient processing. Memory cards are slower, making direct access impractical.
Conclusion
Thus, the correct answer is option 'C' (Memory Card), as it is not directly accessible by the CPU compared to RAM, Cache, and ROM. Understanding these distinctions helps in grasping how computers manage data and memory efficiently.