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Categories >> Software >> Embedded Systems >> 86 Family


 86 Family interview questions  86 Family Interview Questions (53)
 VLSI interview questions  VLSI Interview Questions (200)
 DSP interview questions  DSP Interview Questions (9)
 Embedded Systems AllOther interview questions  Embedded Systems AllOther Interview Questions (24)
What happens during DMA transfer?
 Question Submitted By :: 86-Family
I also faced this Question!!     Answer Posted By  
# 1
DMA means Direct memory access which is used to share the
bulk of data without involving of microprocessor. in this
process the microprocessor will be idle and it uses +5V
power supply.
Is This Answer Correct ?    28 Yes 2 No
# 2
during dma transfer the processor is going with its current
processes and not involved with the data transfers ,since it
already released its buses the for that ...
Is This Answer Correct ?    21 Yes 6 No
# 3
During DMA transfers DMA manager takes control of the
transfer of data from specified source address to
destination address. 1D-1D or 1D-2D or 2D-1D or even 2D-2D
transfers are usually possible. During this time processor
is free to perform other operations - which are independent
of the impending transfer being performed.
Is This Answer Correct ?    13 Yes 3 No
Vinay M K
# 4
During dma operation data tranfer takes place directly to
the peripheral devices,MPU releases the control of the
buses to the dma controler and two new signals are comes
into existence,(1)hold (2)hlda(hold acknowledge)
Is This Answer Correct ?    12 Yes 2 No
# 5
DMA (Direct Memory Access) is a technique that transfers
data between a microprocessor's memory and an I/O device
without involving the microprocessor.

* Working process of DMA controller:

1. The I/O device request DMA operation via the DMA request
lines of the controller chip.

2. The controller chip activates the microprocessor HOLD
pin, requesting the CPU to release the bus.

3. The processor then sends HLDA (Hold Acknowledgement) back
to the DMA controller.

4. The DMA controller completes the DMA transfer and
releases the bus.
Is This Answer Correct ?    3 Yes 0 No
Niaz Mohammad
# 6
THE DMA use the data bus and the microprocessor is not
involved but during this time it can do other tasks which
do not require the data bus such as ALU operation,..
Is This Answer Correct ?    7 Yes 5 No
# 7
The CPU communicates with the DMA through the address and
data buses as with any interface unit. The DMA has its own
address, which activates the DS and RS lines. The CPU
initialize the DMA through the data bus. Once the DMA
receives the start control command, it can start the
transfer between the peripheral device and the memory
Is This Answer Correct ?    2 Yes 0 No
# 8
At the time of DMA operation the micro processor can do any
other task
Is This Answer Correct ?    9 Yes 13 No
# 9
the processor can do any task other task during dma operation 
Is This Answer Correct ?    0 Yes 14 No

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8085 is how many bit microprocessor?   18
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in a sn SR latch made by using cross coupling of two nand gates, if both S andR inputs set o then it will result ISRO 1
Which line will be activated when an output device require attention from CPU?   3
What is an interrupt?   13
can microcontroller work indepandently   3
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