Computer Organization Video Presentation
- 1. I K B 2 0 8 0 3 - C O M P U T E R O R G A N I Z A T I O N TOPIC 6: DIRECT MEMORY ACCESS Presented to: Ts Wan Hazimah binti Wan Ismail
- 2. MEET THE Team NURSOFEA BALQISH BINTIMD NOR 52224123504 MOHAMAD SYAKIR BIN SALLEHUDDIN 52224123526 SITIUMAIRAH BINTI MOHAMMAD SAIFUL 52224123559 MOHAMMAD ROSHAN AMIRUL BIN MOHAMMAD RAIF 52215123492
- 3. BYTE Lorem ipsum dolor sit amet, consectetur adipiscing elit.Proin ac odio at duialiquam tempus sed sed purus. BUR Lorem ipsum dolor sit amet, consectetur adipiscing elit.Proin ac odio at duialiquam tempus sed sed purus. 2020 Lorem ipsum dolor sit amet, consectetur adipiscing elit.Proin ac odio at duialiquam tempus sed sed purus. CONTENT Introduction What is Dma Type of Dma Needs of Dma Dma data transfer Basic operation of Dma Dma Data transfer Data transfer mode Advantage & Disadvantage
- 4. INTRODUCTION OF DMA BYTE Lorem ipsum dolor sit amet, consectetur adipiscing elit.Proin ac odio at duialiquam tempus sed sed purus. BUR Lorem ipsum dolor sit amet, consectetur adipiscing elit.Proin ac odio at duialiquam tempus sed sed purus. 2020 Lorem ipsum dolor sit amet, consectetur adipiscing elit.Proin ac odio at duialiquam tempus sed sed purus. The direct memory access(DMA) I/O technique provides direct access to the memory while the microprocessor is temporarily disabled. The DMA transfer is used to do high- speed memory-to memory transfers Used in disk controllers, cideo/sound cards et,or between memory locations
- 5. DIRECT MEMORY ACCESS (DMA) DIRECT MEMORY ACCESS(DMA) IS A FEATURE OF COMPUTERIZED SYSTEMS THAT ALLOWS CERTAIN HARDWARE SUBSYSTEMS TO ACCESS MAIN SYSTEM MEMORY INDEPENDENTKY OF THE CENTRALPROCESSING UNIT (CPU). DIRECT MEMORY ACCESS IS A MEANS OF HAVING A PERIPHERAL DEVICE CONTROL A PROCESSOR’S MEMORY BUS DIRECTLY . What is DIRECT MEMORY ACCESS (DMA)?
- 6. based data transfer techniques Byte/ cycle stealing mode Burst/ demand mode Continuous/ block mode TYPE OF DMA
- 7. 1) CYCLE STEAL Aread or write signal is generated by the DMAC, and the I/O device either generates by the DMAC effectively steals cycles from the processor in order to transfer the byte, so single byte transfer is also known as cycle stealing
- 8. 2) BURST TRANSFER To achieve block transfers, some DMAC’s incorporate an automatic sequencing of the value presented on the address bus.Aregister is used as a byte count, being decremented for each byte transfer, and upon the byte count reaching zero, the DMAC will release the bus. When the DMAC operates in burst mode, the CPU is halted for the duration of the data transfer.
- 9. 3) CONTINUOUS It is possible to perform hidden DMA, which is transparent to the normal operation of the COU. In the words, the bus is grabbed by the DMAC when the processor is not using it. The DMAC monitors the execution of the processor, and when it recognises the processor executing an instruction whic has sufficient empty clock cycles to perform a byte transfer.
- 10. DMA, ORdirect MemoryAccess, is asub controller that can access memory in sequential order without intervention from the processor. DMAis used to moving around large amounts of datain the computer without taking time away from the processor. The first major uses of DMAincluded drive controllers and sound card. NEED of D M A
- 11. D M A DATA TRANSFER IT IS DATA TRANSFER TECHNIQUE DIRECTLY BETWEEN MEMORY AND I/O WITHOUT CPU INTERVENTION. UNDER THE SUPERVISION OF EXTRA HARDWARECALLED DMACONTROLLER. FASTEST TYPE OF DATA TRANSFER TECHNIQUE AMONG THIS PARALLEL GROUP DMA Data Transfer
- 12. DMA T ransfer 3. microprocessor send HLDA to DMA Controller & DMA takes charge of system bus. 4.DMA give DMA ACK(back) signal to I/O devices 5.now, DMA controller places memory adress on adress bus and data bytes from memory transfer to I/O. 6.DMA controller updates memory adress register and word count register. 7.when internal count =0 then DMA Controllers sets HOLD=0 8.now processor regain the charge od the system bus which continues the normal operation. 1.The I/O device asserts DRQ signal. 2.DMA controller send HOLD signal to microprocessor
- 13. DMAprovide direct access to memory For fast operation of DMAwoek as abus master Direct MemoryAccess is amethod of transferring data between peripherals and memory without using the CPU BASIC Operation’sof DM A
- 16. OUR DATA TRANSFER MODES 1. Single Transfer Mode 2. BlockTransfer Mode 3. Demand Transfer Mode 4. Cascade Mode 5. Memory to memory transfer
- 17. 1 2 3 4 5 0 50 100 150 200 tra nsf er DATA 2. BLOCKTRANSFERMODE Once the DMAcontroller is granted access to the system bus by the CPU, it transfers all bytes of the data in the data block. This mode is called ‘Block Transfer Mode’.once a Block transfer is started, it runs untill the transfer count reaches zero. 1.SINGLETRANSFERMODE In Single Transfer Mode the device is programmed to make one transfer only. in single mode only one byte is transferred per request
- 18. 1 2 3 4 5 0 50 100 150 200 Transfer DATA 4. CASCADEMODE Used to cascade additional DMAcontrollersActual bus signals is executed by cascaded chip. 5. MEMORYTO MEMORY TRANSFER To perform the transfer of the block of data from one set of memory adress to another one, this mode is used, This means data can be transferred from one memory device to another memory device 3. DEMAND TRANSFERMODE Demand mode DMA allows PC hardware to transfer many bytres of data, via a DMA channel, with only a single programming of the DMAcontroller.
- 20. ADVANTAGED M A 1. DMA ALLOWS A PERIPHERAL DEVICE TO READ FROM/WRITE TO MEMORY WITHOUT GOING THROUGH THE CPU 2. DMA ALLOWS FOR FASTER SINCE THE PROCESSOR CAN BE WORKING ON SOMETHING ELSE WHILE THE PERIPHERAL CAN BE PO[ULATING MEMORY.
- 21. DISADVANTAGE D M A 1. DMA TRANSFER REQUIRES A DMA CONTROLLER TO CARRY OUT THE OPERATIONS, HENCE COST OF THE SYSTEM INCREASES. 2.CASHE COHERENCE PROBLEM
- 22. THANK YOU