Understanding DMA (Direct Memory Access)
Direct Memory Access (DMA) is a feature that allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU). In this context, let's explore why the correct answer is option 'C' - DMA CPU.
Why DMA CPU Requires Local Memory and Program
- Dedicated Resources: The DMA controller operates as a separate entity that manages data transfers between memory and peripherals without CPU intervention. This requires its own local memory to store transfer details and a program or control logic to manage these operations.
- Autonomous Operation: The DMA CPU needs to function autonomously. It cannot rely solely on the CPU for instructions during data transfers. Therefore, it necessitates a set of instructions (program) to execute data transactions efficiently.
- Efficiency Boost: With its own memory and program, the DMA CPU can handle multiple data transfers without waiting for the CPU to become available, significantly improving system performance.
Other Options Explained
- DMA Controller: While it manages data transfers, it typically does not require a large local memory or complex programs as it is controlled by the CPU.
- DMA Address: This is simply a reference point in memory and does not involve any processing or memory requirements.
- DMA Peripheral: This refers to the devices involved in data transfer but does not necessitate local memory or a program, as it relies on the DMA controller.
Conclusion
In summary, the DMA CPU is unique in requiring dedicated local memory and a program to facilitate independent and efficient data transfers, distinguishing it from other DMA components.