Explain functions of direct memory access, Computer Engineering

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

Posted Date: 7/19/2013 5:37:59 AM | Location : United States







Related Discussions:- Explain functions of direct memory access, Assignment Help, Ask Question on Explain functions of direct memory access, Get Answer, Expert's Help, Explain functions of direct memory access Discussions

Write discussion on Explain functions of direct memory access
Your posts are moderated
Related Questions
Determine the hardware for multiplication The hardware for multiplication consists of equipment given in Figure. The multiplier is stored in register and its sign in Q . The se

Q. (192.8)10 - (AE.E)16 = (X)8, Find value of x. Use 8's complement method. Q. Write first 10 numbers in the base 4. Q. Explain Error-Detection code & Error-correction code w

Q. What do you mean by Execution Unit? Execution unit performs all ALU operations. Execution unit of 8086 is of 16 bits. It also contains the control unit that instructs bus in

2) Consider the following neural network for two predictors Thickness and Alignment and two classes Print Quality High and Low. Some weights are shown in the table, including weigh

When Workday opened in 2005, the company had no idea it would be regarded as the most successful IPO of 2012. The introduction of cloud computing into the HR and financial systems

Differentiate between exception and validation testing. - Validation testing is done to test the software in conformance to the needs specified. It aims to demonstrate that the

Q. What is Keyboard Layout? A keyboard layout is arrangement of keys across the keyboard. There is one keyboard layout which anybody who has worked on a standard keyboard or ty

Some famous projects on cluster computing are as follows: High Net Worth Project: (developed by: Bill McMillan, JISC NTI/65 - The HNW Project, University of Glasgow, The prim

Design a BCD to excess 3 code converter using minimum number of NAND gates. Hint: use k map techniques. Ans. Firstly we make the truth table: BCD no

The access time of ROM using bipolar transistors is about ? Ans. About 1 µ sec is the access time of ROM using bipolar transistors.