A Top-Level View Of Computer Function And Interconnection Chapter 3 Lecture 06 Faheem ahmad Lecturer, CNET Dept., Jazan University, Jazan KSA A Top-Level View Of Computer Function And Interconnection

Topics of this chapter Computer components Computer functions Instruction fetch and execute Interrupts Interconnection structure and Bus Interconnections

Von Nuemann Three key concepts 1. Data and Instruction are stored in memory. 2. The contents of memory are addressable by location. 3.Execution occur sequentially.

Components There are 3 components of a computer. Central processing unit Memory unit Input and Output unit CPU is the place where actual processing is done on data. The main component of CPU is control unit, the function of control unit is to control computer’s memory, ALU performs computer data processing. Memory Unit stores the data given by the input device. Input and Output Unit is responsible for sending data in and getting processed data out.

Hardwired program Process of connecting various components in configuration to form a program.

software A sequence of codes or instruction is called software.

Instruction Cycle Two steps: Fetch Execute Book Page No 70 Instruction Cycle Processing required for a single instruction is called an instruction cycle. Basic instruction cycle consists of the following phases: a. b. c. d. Fetch and instruction from memory. Decode the instruction. Read the effective address from the memory, if the instruction has an indirect address. Execute the instruction. Book Page No 70

Fetch: The processor reads (fetches) instructions from memory one at a time and executes each instruction. Execute: Program execution consists of repeating the process of instruction fetch and instruction execution.

Fetch Cycle Processor fetches instruction from memory location pointed to by PC Program Counter (PC) holds address of next instruction to fetch Increment PC Book Page No 69 - 70

Execute cycle Instruction loaded into Instruction Register (IR) Processor interprets instruction and performs required actions:

Continue.. Actions Processor-memory Processor I/O Data processing Data transfer between CPU and main memory Processor I/O Data transfer between CPU and I/O module Data processing Some arithmetic or logical operation on data Control Alteration of sequence of operations e.g. jump Combination of above Book Page No 69 - 70

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