Bus aribration

Bus aribration

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  BUS ARBITRATION SUBMITTED TO SUBMITTEDBY SHASHANK SHARMA SAIYAM AGRAWAL (LECTURER of ECS-302) RAHUL SINGH RAWAT FET GKV
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  CONTENT INTRODUCTION OF BUS BUS ARBITRATION CATEGORIZED OF BUS ARBITRATION  CENTRALIZATION ARBITRATION  PROCESS OF CENTRALIZATION ARBITRATION DISTRIBUTED ARBITRATION PROCESS OF DISTRIBUTED ARBITRATION NEEDS FOR BUS ARBITRATION DIRECT MEMORY ACCESS USE OF DIRECT MEMORY ACCESS
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  INTRODUCTION OF BUS BUSis a common pathway connecting two or more devices. DATA AND ADDRESS LINE:- Data, address and complex command CONTROL LINES:- 1)-Signal request and acknowledgement. 2)-Indicate what type of information on data. BUS TRANSITON CONSIST OF:- 1)- Master issuing the command (and Address) -request 2)-Slave receiving ( or sending the data) -action 3)-Defined by what transition does to memory- -Input:- inputs data from the I/O device to the memory -Output – outputs data from the memory to the I/O device BUS MASTE R BUS SLAVE CONTOL LINE:-MASTER INITATE REQUEST DATA LINE :- DATA CAN GO EITHER WAY
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  BUS ARBITRATION Bus Arbitrationis the process by which the next device to become the bus master selected is selected and bus mastership is transferred to it.tne selection of the bus master take into account the need of various device by establishing a priority system for gaining access to the bus. OR Arbitration is the process when more than one module controlling the bus. Example:-CPU & DMA Controller. Only one module may control bus system at a time .
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  CATEGORIZED It can becategorized into 2 parts- 1)CENTRALIZED 2)DISTRIBUTED
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  CENTRALIZED ARBITRATION It is asingle hardware device for controlling bus access. It is a bus controller. Bus arbitration represent. It may be part of CPU or separate. The processor is normally the bus master unless it grant bus mastership to one of the DMA controller.
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  CENTRALIZATION ABRITRATION PROCESSO R DMA CONTROLLE R 1 DMA CONTROLLER 2 BUS REQUEST LINE BUSY BUS BG1BG2
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  DISTRIBUTED ARBITRATION Each module mayclaim the bus. Control logic is present on own module. Bus arbitrator may be or not. Decentralized arbitration has the advantage of offering higher reliability because operation of the bus is not dependent on any single device.
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  DISTRIBUTED ARBITRATION Bus arbitrator 2 Ack Req Bus arbitrator 1 Ack Req Bus arbitrator 3 Ack Req Bus arbitrator 4 Ack Req 4x2 Priority encoder 2x4 Decoder Bus bus y line
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  NEEDS FOR BUS ARBITRATION Multipledevices may need to use the bus at the same time so must have a way to arbitrate multiple requests Bus arbitration schemes usually try to balance: • Bus priority – the highest priority device should be serviced first • Fairness – even the lowest priority device should never be completely locked out from the bus. Bus arbitration schemes can be divided into four classes • Daisy chain arbitration – see next slide • Distributed arbitration by self-selection – each device wanting the bus places a code indicating its identity on the bus
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  DIRECT MEMORT ACCESS (DMA) Aspecial control unit may be provided to allow of transfer of block of data directly between an external device and the main memory , without continuous intervention by the processor .This approach is called DIRECT MEMORY ACCESS (DMA).  To transfer large blocks of data at high speed, an alternative approach is used . DMA transfer are performed by a control unit that is a part of the input or output device interface. The DMA controller perform the function that would normally be carried out by the processor when accessing the memory.
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  USE OF DMACONTROLLER IN COMPUTER DISK OR DMA CONTROLLER PROCESSOR DISK DMA CONTROLLE R KEYBOAR D PRINTE R NETWORK INTRFACEDISK MAIN MEOMERY SYSTEM BUS
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  BIBLOGRAPHY  in Lectureof ECS-302 by Shri SHASHANK SHARMA sir. Book “Computer system architecture” by M.MORRIS MANO. Book “Computer organization” by CARL HAMACHER ,ZVONKO VRANSIC & SAFWAT ZAKY. Ppt by JANIE IRWIN.
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  THANK YOU