DirectMemoryAccessStructure: Used for high-speed I/O devices able to transmitinformation at close to memory speeds Device controller transfers blocks of data frombuffer storage directly to main memory withoutCPUintervention Only one interrupt is generated per block, ratherthan the one interrupt per byte
Direct Memory Access Structure • Used for high-speed I/O devices able to transmit information at close to memory speeds • Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention • Only one interrupt is generated per block, rather than the one interrupt per byte
How a Modern Computer Works-instructionexecution→cachecycleinstructionsthreadofexecutionand-datamovement-dataCPU(*N)/OrequestinterruptDMAdatamemorydevice(*M)
How a Modern Computer Works
Overview of Computer System-System Organization-Storage Structure-System Architecture18
Overview of Computer System -System Organization -Storage Structure -System Architecture 18
Computer-SystemArchitectureMost systems use a single general-purposeprocessor- One main CPU capable of executing general-purposeinstruction setMay have special-purpose processors as well-Device-specific processors: disk, keyboard, etc..-Run a limited instruction set-Do not run user processes-Managed byOS or built intothehardware
Computer-System Architecture • Most systems use a single general-purpose processor – One main CPU capable of executing general-purpose instruction set • May have special-purpose processors as well – Device-specific processors: disk, keyboard, etc. – Run a limited instruction set – Do not run user processes – Managed by OS or built into the hardware
Computer-SystemArchitectureMultiprocessors systems grow in use and importance-Alsoknownasparallelsystems,multicoresystemsAdvantagesinclude:-Increased throughput-Economyofscale:shareperipherals,massstorageandpowersupply-lncreased reliability-graceful degradation orfaulttoleranceTwotypes-AsymmetricMultiprocessing-eachprocessoris assigned aspecie task: boss-worker relationshipSymmetricMultiprocessing(SMP)-eachprocessorperforms all tasks: all processors are peers
Computer-System Architecture • Multiprocessors systems grow in use and importance – Also known as parallel systems, multicore systems • Advantages include: – Increased throughput – Economy of scale: share peripherals, mass storage and power supply – Increased reliability – graceful degradation or fault tolerance • Two types – Asymmetric Multiprocessing – each processor is assigned a specie task: boss-worker relationship – Symmetric Multiprocessing (SMP) – each processor performs all tasks: all processors are peers