Explain functions of direct memory access, Computer Engineering

Assignment Help:

Q. Explain functions of direct memory access?

Though CPU intervention in DMA is minimised however it should use path between interfaces that is system bus. So DMA involves an extra interface on system bus. A scheme known as cycle stealing permits DMA interface to transfer one data word at a time, after that it should return control of bus to processor. Processor merely delays its operation for one memory cycle to permit directly memory I/O transfer to 'steal' one memory cycle. When an I/O is requested processor issues a command to DMA interface by transmitting to DMA interface the subsequent information (Figure below): 

  • Which operations (write or read) to be performed using write or read control lines.
  • Address of I/O devices that is to be used communicated on data lines.
  • Starting location on memory where information will be read or written to be communicated on data lines and is stored by DMA interface in its address register.
  • Number of words which are to be read or written is communicated on data lines and is stored in data count register.

927_Explain functions of direct memory access.png

Figure: DMA block diagram


Related Discussions:- Explain functions of direct memory access

Which scheduling is suitable for time-shared operatin system, Which schedul...

Which scheduling policy is most suitable for a time-shared operating system? Ans. Round-Robin scheduling policy is most appropriate for a time-shared operating system.

Grid security, i just want the experiment to be taken , on Grid Security......

i just want the experiment to be taken , on Grid Security........

Explain language processing, System Software 1. Explain language proces...

System Software 1. Explain language processing? Explain its activities in detail. 2. Discuss briefly about Assembler directives. Also explain about Macro definition and call

Explain XLAT instruction with help of example, Q. Explain XLAT instruction ...

Q. Explain XLAT instruction with help of example? Let's presume a table of hexadecimal characters signifying all 16 hexadecimal digits in table: HEXA      DB      '012345678

Double negation - artificial intelligence, Double Negation - Artificial int...

Double Negation - Artificial intelligence: Always parents are correcting their children for the use of double negatives, but we have to be very alert with them in natural langu

Push and pop, i want flowchart for push, pop in stack element and display s...

i want flowchart for push, pop in stack element and display stack and exit

Give brief description about arithmetic processing unit, Give brief descrip...

Give brief description about arithmetic processing unit To execute the arithmetic operations there is a separate section known as arithmetic processing unit in CPU. The arithme

General principles of pruning, General principles of pruning: The gene...

General principles of pruning: The general principles are such that: 1. Given a node N that can be chosen by player one, thus if there is another node, X, along any path,

What is preemptive and nonpreemptive scheduling, What is preemptive and non...

What is preemptive and nonpreemptive scheduling? Under nonpreemptive scheduling once the CPU has been allocated to a process, the process keeps the CPU unless it releases the C

Compute the positive integer and square root, Question: Q1) Write a cod...

Question: Q1) Write a code that asks the user for a positive integer, computes the square root of that integer, and return the result to the user. The computational error needs

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd