Indira Gandhi
National Open University
presents
A Video Lecture
Course:
Computer Platforms
The von Neumann
Architecture
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 Codes
Instruction
Interpreter
Control
Data
Signals
Instruction
Processor
Results
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
AC
Arithmetic
Logic Unit
Arithmetic-Logic
Circuits
InputOutput
System
MBR
Instructions and Data
Control Unit
PC
IR
Control
Circuits
MAR
Control
Signals
Address
Instruction
Instruction
:
Data
Data
:
Main Memory
AC
Arithmetic
Logic Unit
Arithmetic-Logic
Circuits
InputOutput
System
MBR
AC
Instructions and Data
Control Unit
IR
Control
Circuits
PC
Arithmetic-Logic
Instruction
Instruction
Address
:
MAR Circuits
Control
Signals
MBR
Data
Data
:
Main Memory
AC
Arithmetic
Logic Unit
Arithmetic-Logic
Circuits
InputOutput
System
PC
MBR
IR
Instructions and Data
Control Unit
MAR
PC
IR
Control
Circuits
Control
Address
MAR
Circuits
Control
Signals
Instruction
Instruction
:
Control
Signals
Data
Data
:
Main Memory
Instruction Execution:
An Example
Instruction Format:
Opcode
0
Address
3 4
15
Integer Format:
S
0
1
15
Example Opcodes
1 Load AC from Memory
0001
2 Store AC to Memory
0010
3 Add to AC from Memory
0101
A typical Program statement
Execution
MEMORY
CPU
Registers
Address
Contents
0011 0000 0000
0001 1001 1000 0000
0011 0000 0001
0101 1001 1000 0001
AC
0011 0000 0010
0010 1001 1000 0001
IR
1001 1000 0000
0000 0000 0000 0011
1001 1000 0001
0000 0000 0000 0010
PC
0011 0000 0000
0001 1001 1000 0000
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