computer architecture

AKT211 – CAO
01 - Introduction to Computer
Organization and Architecture
Parahyangan Catholic University
August 22, 2011
What is computer architecture?
What is computer organization?
Computer function & structure
Instruction cycle
People about computer architecture :
• Baer : “The design of the integrated
system which provides a useful tool to the
• Hayes : “The study of the structure,
behavior and design of computers”
• Foster : “The art of designing a machine
that will be a pleasure to work with”
The different usages of the term:
• The design of a computer’s CPU architecture,
instruction set, addressing modes
• Description of the requirements (especially speeds
and interconnection requirements) or design
implementation for the various parts of a computer.
(such as memory, motherboard, electronic
peripherals, or most commonly the CPU)
• Architecture is often defined as the set of machine
attributes that a programmer should understand in
order to successfully program the specific computer
In general, computer architecture refers to attributes of
the system visible to a programmer, that have a direct
impact on the execution of a program
Architecture vs Organization
• Architecture is those features/attributes visible
to the programmer
– Instruction set, number of bits used for data
representation, I/O mechanisms, addressing
– e.g. Is there a multiply instruction?
• Organization is the hardware implementation of
– Control signals, interfaces, memory
– e.g. Is there a hardware multiply unit or is it
done by repeated addition?
Structure & Function
• Structure : the way in which
components are interrelated
• Function : the operation of
individual components as part of
the structure
Functional View
Computer main functions :
1. Data processing
2. Data storage
3. Data movement
4. Control
Operation a) Data Movement
Operation b) Storage
Operation c) Processing
from/to storage
Operation d) Processing from
storage to I/O
Structure – Top Level
Structure – Top Level (2)
1. CPU (Central Processing Unit)
– controls the operation of the computer
and performs its data processing functions
2. Main Memory
– stores data
3. Input/Output (I/O)
– moves data between the computer and its
external environment
4. System interconnection
– mechanism that provides for
communication among CPU, main
memory, and I/O
– transferring data via Bus
Structure – The CPU
Structure – the CPU(2)
1. Control Unit
– controls the operation of the CPU
2. Arithmetic and Logic Unit (ALU)
– performs the computer’s data
processing functions
3. Registers
– provides storage internal to the CPU
4. CPU interconnection
– mechanism that provides for
communication among control unit, ALU,
and registers
Structure – the Control Unit
Structure – Top Level Components
Instruction Cycle
• 2 steps :
1. Fetch
2. Execute
Fetch Cycle
1. Program Counter (PC) holds address
of next instruction to fetch
2. Processor fetches instruction from
memory location pointed to by PC
3. Increment PC unless instructed
4. Instruction loaded into Instruction
Register (IR)
5. Processor interprets instruction and
performs required actions
Execute Cycle
• Processor-memory
– data transfer between CPU and main
• Processor I/O
– Data transfer between CPU and I/O
• Data processing
– Some arithmetic or logical operation on
• Control
– Alteration of sequence of operations, e.g.
• Combination of above
Instruction Cycle – State Diagram
 What is computer architecture?
 What is computer organization?
 Computer function & structure
 4 main functions of computer
 the top level structure of computer
 the functions of computer’s basic
Instruction cycle
 2 steps
Any Question ?
7 Minutes Review
• What are the differences between
computer architecture and
organization? Give your own brief and
clear explanation.
• In your opinion, what is your
expectation after studying today’s
material ? What are the advantages ?