1.Basic Structure of Computer System.ppt

1.Basic Structure of Computer System.ppt

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  NEHRU INSTITUTE OFENGINEERING AND TECHNOLOGY “Nehru Gardens” T. M. PALAYAM, COIMBATORE-105 (Approved by AICTE and Affiliated to Anna University, Chennai) (Accredited by NAAC, Recognized by UGC with 2(f) and 12(B)) NBA Accredited UG Courses: AERO, CSE, MECH DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING CS8491 – COMPUTER ARCHITECTURE PREPARED BY G.JEEVANANTHAM, AP/CSE, NIET.
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  Basic Structure ofComputer System
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  UNIT I BASICSTRUCTURE OF A COMPUTER SYSTEM 9 Functional Units – Basic Operational Concepts – Performance – Instructions: Language of the Computer – Operations, Operands – Instruction representation – Logical operations – decision making – MIPS Addressing.
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  Functional Units Figure 1.1.Basic functional units of a computer. I/O Processor Output Memory Input and Arithmetic logic Control
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  Information Handled bya Computer • Instructions/machine instructions  Govern the transfer of information within a computer as well as between the computer and its I/O devices  Specify the arithmetic and logic operations to be performed  Program • Data  Used as operands by the instructions  Source program • Encoded in binary code – 0 and 1
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  Memory Unit • Storeprograms and data • Two classes of storage  Primary storage  Fast  Programs must be stored in memory while they are being executed  Large number of semiconductor storage cells  Processed in words  Address  RAM and memory access time  Memory hierarchy – cache, main memory  Secondary storage – larger and cheaper
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  Arithmetic and LogicUnit (ALU) • Most computer operations are executed in ALU of the processor. • Load the operands into memory – bring them to the processor – perform operation in ALU – store the result back to memory or retain in the processor. • Registers • Fast control of ALU
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  Control Unit • Allcomputer operations are controlled by the control unit. • The timing signals that govern the I/O transfers are also generated by the control unit. • Control unit is usually distributed throughout the machine instead of standing alone. • Operations of a computer:  Accept information in the form of programs and data through an input unit and store it in the memory  Fetch the information stored in the memory, under program control, into an ALU, where the information is processed  Output the processed information through an output unit  Control all activities inside the machine through a control unit
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  The processor :Data Path and Control PC Register Bank Data Memory Address Instructions Address Data Instruction Memory A L U Data Register # Register # Register # Two types of functional units: elements that operate on data values (combinational)  elements that contain state (state elements)
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  Five Execution Steps Stepname Action for R-type instructions Action for Memory-reference Instructions Action for branches Action for jumps Instruction fetch IR = MEM[PC] PC = PC + 4 Instruction decode/ register fetch A = Reg[IR[25-21]] B = Reg[IR[20-16]] ALUOut = PC + (sign extend (IR[15-0])<<2) Execution, address computation, branch/jump completion ALUOut = A op B ALUOut = A+sign extend(IR[15-0]) IF(A==B) Then PC=ALUOut PC=PC[31- 28]||(IR[25- 0]<<2) Memory access or R-type completion Reg[IR[15-11]] = ALUOut Load:MDR =Mem[ALUOut] or Store:Mem[ALUOut] = B Memory read completion Load: Reg[IR[20-16]] = MDR
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