20CS001 – COMPUTER ORGANIZATION
AND ARCHITECTURE
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Text Book:
David A. Patterson and John L. Hennessey, “Computer Organization and Design: The
Hardware / Software Interface”, Morgan Kaufman / Elsevier, ARM Edition, 2017.

Architecture: An Overview
Functional units of a Digital Computer – Translation from a High level
language to Hardware Language – Technology – Performance – Power wall –
Uniprocessor to multiprocessor - Instructions: Operations and Operands –
Instruction Set: RISC and CISC - Representing Instructions - Logical
Operations – ARM Addressing for 32-bit Immediate and more complex
addressing modes.
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The Computer Revolution
 Progress in computer technology
Computers in automobiles
Cell phones
World Wide Web
Search Engines
Computers are pervasive.
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Classes of Computers
 Personal computers
General purpose, variety of software
Subject to cost/performance tradeoff
 Server computers
Network based
High capacity, performance, reliability
Range from small servers to building sized
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MIPS

Classes of Computers (Cont.)
 Supercomputers
High-end scientific and engineering calculations
Highest capability but represent a small fraction of the overall computer
market
 Embedded computers
Hidden as components of systems
Stringent power/performance/cost constraints
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FLOPS / GFLOPS

The PostPC Era
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The PostPC Era
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 Personal Mobile Device (PMD)
Battery operated
Connects to the Internet
Hundreds of dollars
Smart phones, tablets, electronic glasses
 Cloud computing
Warehouse Scale Computers (WSC)
Software as a Service (SaaS)
Portion of software run on a PMD and a portion run in the Cloud
Amazon and Google

Functional Units
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Few Parts of a Computer – An Overview
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Assemble the computer: https://www.youtube.com/watch?v=hWB2UHCT0dw

Computer Working Principles
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I/O system
Processor
Compiler
Operating
System
(Mac OSX)
Application (ex: browser)
Digital Design
Circuit Design
Instruction Set
Architecture
Datapath & Control
transistors
Memory
Hardware
Software Assembler

What We Will Learn
 How programs are translated into the machine language
 How the hardware executes them
The hardware/software interface
What determines program performance
And how it can be improved
How hardware designers improve performance
What is parallel processing
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Eight Great Ideas
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 Design for Moore’s Law
 Use abstraction to simplify design
 Make the common case fast
 Performance via parallelism
 Performance via pipelining
 Performance via prediction
 Hierarchy of memories
 Dependability via redundancy

1. Design for Moore’s Law
 Moore’s Law. It states that integrated circuit resources double every
18–24 months.
 Computer Architects must anticipate where the technology will be when the
design finishes rather than design for where it starts.
 The resources available per chip can easily double or quadruple between the
start and finish of the project.
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2. Use Abstraction to Simplify Design
 A major productivity technique for hardware and software is to
use abstractions to represent the design at different levels of
representation.
 lower-level details are hidden to offer a simpler model at higher
levels.
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3. Make the Common Case Fast
 Making the common case fast will tend to enhance performance
better than optimizing the rare case.
The common case is often simpler than the rare case and hence is
often easier to enhance.
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4. Performance via Parallelism
 Computer architects have offered designs that get more
performance by performing operations in parallel.
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5. Performance via Pipelining
 A particular pattern of parallelism performed in computer
architecture is named as “pipelining”.
Performance can be achieved by overlapping the execution of
successive instructions.
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6. Performance via Prediction
 In some cases it can be faster on average to guess and start
working rather than wait until you know for sure.
Assuming that the mechanism to recover from a misprediction is
not too expensive and your prediction is relatively accurate
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7. Hierarchy of Memories
 Programmers want memory to be fast, large, and cheap.
Hierarchy of Memories, with the fastest, smallest , and most
expensive memory per bit at the top of the hierarchy and the
slowest, largest, and cheapest per bit at the bottom.
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8. Dependability via Redundancy
 Computers need to be dependable.
When any physical device fail, we make systems dependable by
including redundant components that can take over when a failure
occurs and to help detect failures.
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Eight Great Ideas
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 Design for Moore’s Law
 Use abstraction to simplify design
 Make the common case fast
 Performance via parallelism
 Performance via pipelining
 Performance via prediction
 Hierarchy of memories
 Dependability via redundancy

Below Your Program
 Application software
Written in high-level language
System software
Compiler: translates HLL code to machine code
Operating System: service code
Handling input/output
Managing memory and storage
Scheduling tasks & sharing resources
Hardware
Processor, memory, I/O controllers
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Levels of Program Code
 High-level language
Level of abstraction closer to
problem domain
Provides for productivity and
portability
Assembly language
Textual representation of instructions
Hardware representation
Binary digits (bits)
Encoded instructions and data
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Example
A compiler enables a programmer to write this high-level
language expression:
A+B
The compiler would compile it into this assembly
language statement:
add A,B
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Components of a Computer
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Same components for
all kinds of computer
Desktop, server,
embedded
Input/output includes
User-interface devices
Display, keyboard, mouse
Storage devices
Hard disk, CD/DVD, flash
Network adapters
For communicating with other
computers

Components of a Computer
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 Five Components
 Input writes data to memory
 Output reads data from memory
 Processor get instruction and
data from memory.
 Control sends the signals that
determine the operations of the
datapath, memory, input, and
output. Datapath performs
operations on data.
 Memory stores data

Computer Hardware in detail…
 Integrated circuit Also called a chip. A device combining dozens to
millions of transistors.
 Central Processor unit (CPU) Also called processor. The active part of
the computer, which contains the datapath and control and which adds
numbers, tests numbers, signals I/O devices to activate, and so on.
 Datapath The component of the processor that performs arithmetic operations
 Control The component of the processor that commands the datapath,
memory, and I/O devices according to the instructions of the program.
 Memory The storage area in which programs are kept when they are
running and that contains the data needed by the running programs.
 CMOS - Complementary Metal-Oxide Semiconductor - system
settings, date, and time
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Computer Hardware in detail…
 Volatile memory: when it loses power, it forgets. (retains data only if it is
receiving power)
 Nonvolatile memory: A form of memory that retains data even in the absence of
a power source and that is used to store programs between runs.
 Main memory (primary memory): Memory used to hold programs while they
are running (DRAM)
 Dynamic Random Access Memory (DRAM) Memory built as an integrated
circuit; it provides random access to any location. Access times are 50
nanoseconds and cost per gigabyte in 2012 was $5 to $10.
 Cache memory A small, fast memory that acts as a buffer for a slower, larger
memory.
 Static Random Access Memory (SRAM) Also memory built as an
integrated circuit, but faster and less dense than DRAM.
 Secondary memory: Nonvolatile memory used to store programs and data
between runs
 Magnetic disk/Hard disk: form of nonvolatile secondary memory composed
of rotating platters coated with a magnetic recording material.
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Computer Hardware in detail…
 Local area network (LAN): A network designed to carry data
within a geographically confined area, typically within a single
building. (1 to 40 gigabits)
 Wide area network (WAN): A network extended over hundreds of
kilometers that can span a continent. Backbone of the Internet,
which supports the web - optical fibers.
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Technologies for Building Processors
and Memory
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 Transistor An on/off switch controlled by an electric signal.
 Integrated circuit (IC) combined dozens to hundreds of transistors
into a single chip.
 Very large-scale integrated (VLSI) circuit A device containing
hundreds of thousands to millions of transistors.
 Ultra large-scale integrated (ULSI) circuit
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Growth of capacity per DRAM chip over time
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The Chip manufacturing process
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