Indira Gandhi National Open University presents

A Video Lecture Course: Computer Platforms

The von Neumann Architecture

Objectives: To define the basic components of a Computer System

The von Neumann Architecture Objectives: To define the basic components of a Computer System To define the functions of various components of computers

The von Neumann Architecture Objectives: To define the basic components of a Computer System To define the functions of various components of computers To define the basic hardware terminology

What is a Computer? A general purpose programmable electronic machine, having two principal characteristics: Responds to a specific set of coded instructions in a well-defined manner. It can execute a pre-recorded list of instructions termed as Program

What is an Instruction An instruction is a binary coded command designed for a specific task such as: –Arithmetic and Logic Instructions –Looping and Decision making –Transfer of data –Transfer of Control

Execution of an Instruction Involves: Get the Instruction Decode the Instruction Get the Operands Perform the desired operation Communicate the results back

Instruction Execution Instruction Processor Instruction Interpreter Control Signals Instruction Codes DataResults

Need of Memory Non-linear Programming Paradigm

Need of Memory Non-linear Programming Paradigm An operation on data may require more than one data value in a predetermined sequence

Need of Memory Non-linear Programming Paradigm An operation on data may require more than one data value in a predetermined sequence Speed of Input vs the speed of Processing Unit

Key Concepts of von Neumann Machine Data and Instructions in a single read-write Memory

Key Concepts of von Neumann Machine The contents of the memory addressable by location irrespective of the type of data stored.

Key Concepts of von Neumann Machine Sequential execution of instruction unless explicitly modifies by an instruction

General Computer Structure Main Memory: For storing Data and Instruction Central Processing Unit: Consisting of Arithmetic-Logic Unit(ALU), Control Unit(CU), and Operational Registers Input and Output System: Operated by the Control Unit

Input- Output System Arithmetic Logic Unit Main Memory Instruction : Data : PC MARIR MBR Arithmetic-Logic Circuits AC Control Circuits Control Signals Address Instructions and Data Control Unit

Input- Output System Main Memory Instruction : Data : PC MARIR MBR Arithmetic-Logic Circuits AC Control Circuits Control Signals Address Instructions and Data MBR Arithmetic-Logic Circuits AC Arithmetic Logic Unit Control Unit

Input- Output System Main Memory Instruction : Data : PC MARIR MBR Arithmetic-Logic Circuits AC Control Circuits Control Signals Address Instructions and Data PC MAR IR Control Circuits Control Signals Arithmetic Logic Unit Control Unit

Instruction Execution: An Example Instruction Format: Integer Format: Opcode Address S

Example Opcodes 1Load AC from Memory Store AC to Memory0010 3Add to AC from Memory0101

A typical Program statement Execution AddressContents MEMORYCPU Registers PC AC IR

So what are the key terms: The BInary digiT. BITs may be used for: –Representation of Opcode –Representation of Character data-ASCII (8bits), unicode (16 bits) –Representation of Numeric data in binary form Integrated Circuits: For implementing electronics for data processing, storage and movement

The Macro Terms Byte, ASCII, Unicode Word ULSI GSI Microprocessors BUS

–The basic components of computer –The concepts of von Neumann machine –Instruction execution with an example and the role played by various components in instruction execution –Some of the basic terminology relating to processors