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

State the important features of operating system, a. Define operating syste...

a. Define operating system? State the important features of operating system? b. Describe the following facilities for implementing interacting processes in programming language

Drill-down features provided by abap/4 in interactive lists, What are the d...

What are the drill-down features provided by ABAP/4 in interactive lists? ABAP/4 gives some interactive events on lists such as AT LINE-SELECTION (double click) or AT USER-COM

What are the different phases of consumer mercantile model, What are the di...

What are the different phases of consumer mercantile model? There are three different phase of consumer mercantile model like listed as in below: • Pre-purchase interaction

Callable modules of program code within one abap/4 program, How can we crea...

How can we create callable modules of program code within one ABAP/4 program? We can create callable modules by two techniques:- By defining Macros. By creating incl

Find out how many words can be formed from daughter, Find out how many word...

Find out how many words can be formed out of the letters of the word DAUGHTER such that (i)  The vowels are all time together. (ii)  The vowels occupy even places.   Ans:

Explain about combinational circuits, Q. Explain about Combinational Circui...

Q. Explain about Combinational Circuits? Combinational Circuit is one of the models for parallel computers. In interconnection networks, different processors correspond with ea

Instruction pipelines, Instruction Pipelines As discussed previous, the...

Instruction Pipelines As discussed previous, the stream of instructions in the instruction implementation cycle, can be realized through a pipeline where overlapped implementat

Explain about behavioral notations, Explain about Behavioral Notations ...

Explain about Behavioral Notations These notations contain dynamic elements of the model.  Their elements comprise interaction and the state machine. It also comprise classe

Name of all sap databases, All SAP Databases are Relational Databases ...

All SAP Databases are Relational Databases is the all sap databases.

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