Dma-how dma works-microprocessor, Assembly Language

Assignment Help:

DMA

  • DMA stands for Direct Memory Access
    • It is uses same Address/Data lines on ISA bus
    • It controls the ISA bus instead of the processor ("bus master")
    • Floppy Drive (DRQ2)
    • Hard Drive (varies)
    • Sound Card (varies)

 

  • DMA vs. Programmed I/O
    • It need less processor load
    • It can continually transfer the same block (loop indefinitely)
    • The devices which are demand-based can be serviced more efficiently

     

  • DMA characteristics:
    • It is 16-bit or 8-bit transfers

 

HOW DMA WORKS to transfer data from memory to a peripheral:

1. The peripheral Device requests for DMA service by pulling DREQ line high

2. The DMA controller requests CPU go on hold by pulling CPU's HRQ line high

3. The CPU finished current bus cycle, then acknowledges with HLDA the CPU relinquishes ALL bus control now (3-state)

4. The DMA controller activates DACK line to acknowledge the DMA to the peripheral

5. The DMA start transferring data to the peripheral

 


Related Discussions:- Dma-how dma works-microprocessor

Cmp-arithmetic instruction-microprocessor, CMP: Compare: - This instructio...

CMP: Compare: - This instruction compares the source operand, which can be a register or memory location an immediate data with a destination operand that might be a register or a

Rep-string manipulation instruction-microprocessor, REP : Repeat Instructi...

REP : Repeat Instruction Prefix :- This instruction is utilized as a prefix to other instructions. The instruction in which the REP prefix is provided, is executed repetitively

Label-assemblers directive-microprocessor, LABEL :   The Label directive...

LABEL :   The Label directive which is used to assign a name to the current content of the location counter. At the beginning of the assembly process, the assembler start a loca

Program, move a byte string ,16 bytes long from the offset 0200H to 0300H i...

move a byte string ,16 bytes long from the offset 0200H to 0300H in the segment 7000H..

Program to accept the input from user, Write an assembly language program t...

Write an assembly language program that will: accept keyboard input of a positive integer value N; compute the sum S= 1+ 2 + 3 + ... + N; print (output) the computed su

Aas-arithmetic instruction-microprocessor, AAS: ASCII Adjust AL After Subt...

AAS: ASCII Adjust AL After Subtraction AAS instruction correct the result in the AL register after subtracting operation of two unpacked ASCII operands. The result is in unpacked

Write an assembly language program, Your assignment for this project is to ...

Your assignment for this project is to write an assembly language program that checks if the user's input is a valid ISBN number. A sample run of your program might look like:

Synchronous and asynchronous transmissions of 8251, Typical link to modems ...

Typical link to modems for synchronous and asynchronous transmissions are shown in Figure. With regard to the synchronous connections it is consider that the timing is controlled

8086 alp, to find the matrix addition

to find the matrix addition

Basic microprocessor architecture and interface, Basic Microprocessor Archi...

Basic Microprocessor Architecture and Interface : Introduction: Intel launches its first 4-bit microprocessor 4004 in the year 1971 and 8-bit microprocessor 8008 in the y

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