about architecture.......................

about architecture

1. Direct Memory Access (DMA) Prepared by : Lavin Jan.2023

2. Outline: What Is Direct Memory Access? DMA Controller: How Direct Memory Access Works? How to Enable Direct Memory Access? Different Modes of Operation: Program.C Transfer vs DMA Transfer Types of Device DMA: Advantages and Disadvantages of DMA:

3. Direct memory access (DMA) is a process that allows specific hardware devices to access system memory independently of the CPU. This enables the device to perform tasks without interrupting the main processor, improving performance . DMA is used for devices such as disk controllers and network cards. You can also use it for data transfer between the memory and peripheral devices such as sound cards and graphics cards. What Is Direct Memory Access? The process is managed by a chip known as a DMA controller (DMAC ).

4. The direct memory access controller is used only for transferring the data, it doesn’t do any modifications, so it reads, writes the data, and verifies the transfer data. The DMA controller operates in two modes they are master mode and slave mode. Whenever the CPU sends the acknowledgment to the DMA controller it acts as master mode, similarly whenever the CPU didn’t send the acknowledgment to the DMA controller then up to that point it acts as a slave. DMA Controller :

5. DMA works by having a dedicated DMA controller that manages the data transfers between memory and the various devices that need to access it. The DMA controller will first need to be configured with the desired source and destination addresses, as well as the size of the data transfer. Once everything is configured, the DMA controller will initiate the transfer and monitor it until it is complete. How Direct Memory Access Works?

6. Windows includes a utility called "Device Manager" that can be used to enable or disable DMA for devices. To access Device Manager, click Start, then type "device manager" into the search box. Device Manager will then show a list of all the devices installed on your computer. Find the device you want to enable DMA for and double-click it to open its properties. In the properties window, go to "Details" tab, then find the "DMA" setting and set it to "Enabled". Save your changes and close Device Manager. How to Enable Direct Memory Access?

7. It is used for large data transfer. It is used for small data transfer. For transferring data, a DMA controller is necessary. The data transfer can be controlled through software. The speed of data transfer is slow. While transferring data,the CPU involves. Additional hardware is required. Program.C Transfer vs DMA Transfer The data transfer can be controlled through hardware . The speed of data transfer is very fast. The CPU is not involved while transferring data.

8. Types of Device DMA: Devices perform one of the following three types of DMA: REGISTER COUNTER

9. C A B Burst mode   Different Modes of Operation: Cycle stealing mode Transparent mode

10. 01 02 03 The work overload on the CPU decreases. For each transfer, only a few numbers of clock cycles are required DMA speedups the memory operations by bypassing the involvement of the CPU. Advantages and Disadvantages of DMA: Advantage:

11. 01 02 Increases the price of the system. if done badly, hard to use. Advantages and Disadvantages of DMA: Disadvantage:

12. Reference: https://www.elprocus.com/direct-memory-access-dma-in-computer-architecture / https://www.watelectronics.com/dma-controller / https:// www.techopedia.com/definition/2767/direct-memory-access-dma https://www.elprocus.com/direct-memory-access-dma-in-computer-architecture/

13. Thanks