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

Difference between the real mode and the protected mode, Problem (a) ...

Problem (a) Explain the difference between the real mode and the protected mode in the 80x86 family of processors. (b) The 32-bit physical address 047C:0048 is to be conv

Program which take input two images by homography, The goal of this questio...

The goal of this question is to create a program that takes as input two images that are related by a homography, and which "warps" the second image (piscine2.bmp) to align with th

Command mode using vi editor, What does the c$ command do from command mode...

What does the c$ command do from command mode using Vi Editor? Ans) C$ will start from the character under the curser till the finish of line. So when you use this command it wi

What is message passing libraries, Q. What is Message Passing Libraries? ...

Q. What is Message Passing Libraries? In this part we will consider about message passing libraries. Traditionally a range of message passing libraries have been available ever

Using aspx view engine, When using aspx view engine, to have a steady look ...

When using aspx view engine, to have a steady look and feel, across all pages of the application, we can build use of asp.net master pages. What is asp.net master pages equal, when

What is drawbacks of cd- rom, Q. What is Drawbacks of CD- ROM? Drawbac...

Q. What is Drawbacks of CD- ROM? Drawbacks of CD- ROM are as below: 1. It is read-only and can't be updated. 2. It has an access time much longer than magnetic disk dri

What is cursor, What is Cursor? Cursor is a database object used by app...

What is Cursor? Cursor is a database object used by applications to manipulate data in a set on a row-by- row basis, instead of the typical SQL commands that operate on all the

Use string manipulating functions , Write a script that will first initiali...

Write a script that will first initialize a string variable that will kept x and y coordinates of a point in the form 'x 3.1 y 6.4'.  Then, use string manipulating functions to ext

List the properties which a hashing function should possess, List the prope...

List the properties which a hashing function should possess to ensure a good search performance. What approaches are adopted to handle collision? A hashing function h must poss

Performance of pipelines with stalls, Performance of Pipelines with Stalls:...

Performance of Pipelines with Stalls: A stall is reason of the pipeline performance to degrade the ideal performance.                                             Average in

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