IntroductionCOMP375 1COMP375Computer Architectureand OrganizationIntroductionIntroductionWhat is Computer Architecture?Hardware• This is a course about what’s inside the bbox.• How does the hardware run the software?• How do hardware design features impact software execution?How does the software interface with the•How does the software interface with the hardware?Architecture and Organization• Architecture is the design of the system visible to the assembly level programmer.visible to the assembly level programmer.– What instructions– How many registers– Memory addressing scheme• Organization is how the architecture is implemented.– How much cache memory– Microcode or direct hardware– Implementation technologyIntroductionCOMP375 2Same ArchitectureDifferent OrganizationAlmost e er program that can r n on an•Almost every program that can run on an original Pentium (or 8086) can run on a Pentium 4.• All computers in the Intel Pentium series have the same architecture.• Each version of the Pentium has a different organization or implementation.Same ArchitectureDifferent OrganizationTh IBM 360 l d i•The IBM 360 computer was released in several different models.• All had the same architecture. A program compiled on one IBM 360 would run on all modelsmodels.• The different models had different implementations, speed and price.Basic Computer ComponentsCPUI/O DeviceCPUI/O ControllerI/O DeviceCacheMemoryBusCentral Processing Unit• Contains the control logic that initiates ttiitiith tmost activities in the computer.• The Arithmetic Logic Units perform the math and logic calculations.• Registers contain temporary data values.Program Counter contains the address of•Program Counter contains the address of the next instruction to execute.IntroductionCOMP375 3Registers• The CPU has registers to temporarily hold data being acted upon.• Different architectures have different number of registers.• Some registers are available for the user programs to use directly.•Some registers are used indirectly (such•Some registers are used indirectly (such as the program counter).• Some registers are used only by the operating system (i.e. program status reg)Bus• The bus is a set of parallel wires that t th CPU d I/Oconnect the CPU, memory and I/O controllers.• It has logic (the chipset) to determine who can use the bus at any given instant.•The width of the bus determines the•The width of the bus determines the maximum memory configuration.I/O Controllers• Direct the flow of data to and from I/O didevices.• CPU sends a request to the I/O controller to initiate I/O.• I/O controllers run independently and in parallel with the CPUparallel with the CPU.• I/O controllers may interrupt the CPU upon completion of request or error.Memory• The internal memory is Random Access M (RAM)Memory (RAM).• Both data and program instructions are kept in RAM.• Instructions must be in RAM to be executedexecuted.IntroductionCOMP375 4Memory Hierarchy Instruction Cycle• Fetch the instruction from memory• Execute the instructionInstruction Cycle (more detail)• Fetch the instruction from the memory dd i th P C t i taddress in the Program Counter register• Increment the Program Counter• Decode the type of instruction• Fetch the operands• Execute the instruction• Store the resultsSimple Model of Execution• Instruction sequence is determined by a il tl tlitsimple conceptual control point.• Each instruction is completed before the next instruction starts.• One instruction is executed at a time.IntroductionCOMP375 5LayersYou can consider computer operation at many different levels.•Applications•Applications• Middleware• High level languages• Machine Language• Microcode• Logic circuits• Gates• Transistors• Silicon structuresFirst Assignment• Complete the online quiz on metric prefixes b930 FidAt20by 9:30am on Friday, August 20• Available on the class website assignments page• Solutions available on the class