DMA CONTROLLER
ARCHITECTURE OF 8085
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Processor
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The process being executed
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I/O devices
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OS
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Detailed explanation-1: -The DMA transfer is initiated by I/O devices. When an I/O device needs to transfer data to or from memory, it sends a request to the DMA controller. The DMA controller then takes over the bus and transfers the data directly between the I/O device and memory without the involvement of the processor.
Detailed explanation-2: -With DMA, the CPU first initiates the transfer, then it does other operations while the transfer is in progress, and it finally receives an interrupt from the DMA controller (DMAC) when the operation is done.
Detailed explanation-3: -Direct memory access (DMA) is a method that allows an input/output (I/O) device to send or receive data directly to or from the main memory, bypassing the CPU to speed up memory operations.
Detailed explanation-4: -Using a DMA controller, the device requests the CPU to hold its data, address and control bus, so the device is free to transfer data directly to/from the memory. The DMA data transfer is initiated only after receiving HLDA signal from the CPU.