Computer Organization
‫تنظيم الحاسبات‬
Dr. Tamer Samy Gaafar
Dept. of Computer & Systems Engineering
Faculty of Engineering
Zagazig University
Course Web Page
http://www.tsgaafar.faculty.zu.edu.eg
Email: tsgaafar@yahoo.com
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Grading:
Course work
Grade distribution
Assignments +
Sections
10pt
Midterm Exam
20pt
30
Final Exam
70pt
Total Points
100
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Ch. 1: Introduction
Ch. 2: A Top-Level View of Computer Function and
Interconnection
Ch. 3: Instruction Set Architecture & Design
Ch. 4: Computer Arithmetic
Ch. 5: Input – Output Design & Organization.
Ch. 6: Memory System Design
Ch. 7: Control Unit
Ch. 8: Introduction to Advanced Computer
Architecture and Parallel Processing
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Architecture: attributes visible to the
programmer.
◦ Instruction set, number of bits used for data
representation,
I/O
mechanisms,
addressing
techniques.
◦ e.g. Is there a multiply instruction?
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Organization: how features are implemented
◦ Control signals, interfaces, memory technology,
number of cores.
◦ e.g. Is there a hardware multiply unit or is it done by
repeated addition?
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All Intel x86 family share the same basic
architecture.
This gives code compatibility, at least
backwards.
Organization differs between different
versions (e.g., Core i3/i5/i7, Xeon, Atom, …
etc.)
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Structure: the way in which components
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Function: the operation of individual
relate to each other.
components as part of the structure
Computer
Peripherals
Central
Processing
Unit
Computer
Main
Memory
Systems
Interconnection
Input
Output
Communication
lines
CPU
Arithmetic
and
Login Unit
Computer
Registers
CPU
Memory
System
Bus
I/O
Internal CPU
Interconnection
Control
Unit
Control Unit
CPU
Registers
Internal
Bus
Control
Unit
ALU
Sequencing
Logic
Control Unit
Registers and
Decoders
Control
Memory
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All computers have the following functions:
◦Data storage
◦Date processing
◦Data movement
◦Control
Data
Storage
Facility
Data
Movement
Apparatus
Control
Mechanism
Data
Processing
Facility
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e.g., keyboard to screen.
Data
Storage
Facility
Data
Movement
Apparatus
Control
Mechanism
Data
Processing
Facility
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e.g., Internet download to a disk.
Data
Storage
Facility
Data
Movement
Apparatus
Control
Mechanism
Data
Processing
Facility
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e.g., updating a bank statement.
Data
Storage
Facility
Data
Movement
Apparatus
Control
Mechanism
Data
Processing
Facility
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e.g., printing a bank statement.
Data
Storage
Facility
Data
Movement
Apparatus
Control
Mechanism
Data
Processing
Facility
1.
2.
3.
Data and instructions are stored in a single
read-write memory.
The contents of this memory are addressable
by location, without regard to the type of
data contained there.
Execution occurs in a sequential fashion
(unless modified) from one instruction to the
next.
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Hardwired program: configuration of logic
components designed specifically for a
particular computation. Inflexible.
General-purpose hardware: can do different
tasks, given correct control signals.
◦ Instead of re-wiring the hardware, supply a new set
of control signals (write a new program).
Customized hardware
Data
Sequence of
arithmetic and logic
functions
Instruction
codes
Instruction
Interpreter
CPU
Results
• Each code is
an instruction.
• A sequence
of codes (or
instructions) is
called
software.
Control
signals
Data
General-purpose
arithmetic and logic
functions
Results
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A sequence of steps.
For each step, an arithmetic or logical
operation could be done.
Each operation result in a different set of
control signals.
◦ A unique code is provided for each operation.
 e.g., ADD  9D, MOVE  E3, … etc.
◦ A hardware segment accepts the code and issues
the control signals
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That’s it. We have a computer!
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The Control Unit and the Arithmetic and Logic
Unit constitute the Central Processing Unit.
Data and instructions need to get into the
system and results out.
◦ Input/Output
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Temporary storage of code and results is
needed.
◦ Main memory.
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Two steps:
◦ Fetch: CPU reads instructions from memory, one at
a time.
◦ Execute: CPU executes instructions.
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Program Counter (PC) holds address of next
instruction to fetch.
Processor fetches instruction from memory
location pointed to by PC.
Increment PC.
◦ Unless told otherwise
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Instruction loaded into Instruction Register
(IR).
Processor interprets instruction and performs
required actions in execute cycle.
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Processor-memory
◦ Data transfer between CPU and main memory
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Processor-I/O
◦ Data transfer between CPU and I/O module
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Data processing
◦ Some arithmetic or logical operation on data
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Control
◦ Alteration of sequence of operations
◦ e.g., jump
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Combination of the above
0
3 4
Opcode
15
Address
Instruction Format
0 1
S
15
Magnitude
Integer Format
Program Counter (PC)
Instruction Register (IR)
Accumulator (AC)
CPU Registers
0001 = Load AC from memory.
0010 = Store AC to memory.
0101 = Add to AC from memory.
Partial List of Opcodes
Fetch cycle
Execute cycle
First instruction
Second instruction
Third instruction
CPU-memory or CPU-I/O operations
Internal CPU operations