[Solved] Which of the following correctly describes how a DMA controller gains control of the bus? — Ans: It sends a request signal and waits for the CPU to grant bus access | ARM Architecture

ARM Architecture - Bus Architecture

Which of the following correctly describes how a DMA controller gains control of the bus?

AIt sends a request signal and waits for the CPU to grant bus access

BIt immediately takes control without any coordination

CIt uses interrupts to stop the CPU permanently

DIt disables all peripherals before transferring data

Step-by-Step Solution

Solution:

Step 1: Understand bus arbitration for DMA
The DMA controller requests control of the bus and waits for the CPU or bus arbiter to grant access to avoid conflicts.
Step 2: Evaluate other options
Immediately taking control would cause conflicts; using interrupts to permanently stop the CPU is incorrect; disabling peripherals is unnecessary.
Final Answer:
It sends a request signal and waits for the CPU to grant bus access -> Option A
Quick Check:
DMA requests bus access before transfer [OK]

Quick Trick: DMA must request bus access, not take it instantly [OK]

Common Mistakes:

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Which of the following correctly describes how a DMA controller gains control of the bus?