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

Find the conversion time & conversion rate of A/D converter, Find the conve...

Find the conversion time of a Successive Approximation A/D converter which uses a 2 MHz clock and a 5-bit binary ladder containing 8V reference. What is the Conversion Rate? An

Indias parallel computers, Parallel Computers In India, the design and ...

Parallel Computers In India, the design and development of parallel computers in progress in the early 80?s. The Indian Government recognized the Centre for Development of Adva

Dbms, aggregation in dbms?

aggregation in dbms?

Describe the contents of a process control block, Describe the contents of ...

Describe the contents of a Process Control Block (PCB). Process Control Block (PCB): All processes are represented in the operating system by a task control block or a proces

Explain topology method used in lan technology in detail, Explain topology ...

Explain topology method used in LAN technology in detail. LAN Topologies: Network topology is a physical schematic that shows interconnection of the various users. There are

Explain keyboard input and video output, Q. Explain Keyboard Input and Vide...

Q. Explain Keyboard Input and Video output ? A Keystroke read from keyboard is termed as a console input and a character displayed on the video screen is known as a console out

Explain the architecture of ss7, Explain the architecture of SS7 . A ...

Explain the architecture of SS7 . A block schematic diagram of the CCITT no. 7 signaling system is demonstrated in figure. Signal messages are passed by the central proces

Describe the importance of micro-programming, Question: (a) Describe t...

Question: (a) Describe the importance of Micro-Programming and point out one area where Micro-Programming is extensively used. (b) Below is a diagram of an 8086 processor.

Describe about instruction set, Q. Describe about Instruction set? Inst...

Q. Describe about Instruction set? Instruction set is the boundary where computer designer and computer programmer see the same computer from various viewpoints. From the desig

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