Part I Background and Motivation

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Part IBackground and Motivation
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I Background and Motivation

• Provide motivation, paint the big picture,
  introduce tools
• Review components used in building digital
  circuits
• Present an overview of computer technology
• Understand the meaning of computer performance
• (or why a 2 GHz processor isnt 2? as fast as
  a 1 GHz model)

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3 Computer System Technology

• Interplay between architecture, hardware, and
  software
• Architectural innovations influence technology
• Technological advances drive changes in
  architecture

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3.1 From Components to Applications
Figure 3.1 Subfields or views in computer
system engineering.
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What Is (Computer) Architecture?
Figure 3.2 Like a building architect, whose
place at theengineering/arts and goals/means
interfaces is seen in this diagram, acomputer
architect reconciles many conflicting or
competing demands.
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3.2 Computer Systems and Their Parts
Figure 3.3 The space of computer systems,
with what we normally mean by the word computer
highlighted.
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Price/Performance Pyramid
Differences in scale, not in substance
Figure 3.4 Classifying computers by
computational power and price range.
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Automotive Embedded Computers
Figure 3.5 Embedded computers are ubiquitous,
yet invisible. They are found in our automobiles,
appliances, and many other places.
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Personal Computers and Workstations
Figure 3.6 Notebooks, a common class of
portable computers, are much smaller than
desktops but offer substantially the same
capabilities. What are the main reasons for the
size difference?
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Computer System Components

• Traditionally, we often group functional computer
  components into five classic categories
• Input Systems (e.g. keyboard, mouse)
• Output Systems (e.g. Monitor display, printer)
• Memory (contains stored programs and memory)
• Control (component that controls memory, I/O,
  datapath)
• Datapath (component that performs arithmetic
  operations)

InputSystems
Controller
Memory
Datapath(regs., ALU)
OutputSystems
Processor (CPU)
I/O systems
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Inside the CPU (a more detailed look)

• Block diagram of a simple, generic CPU

CPU
Instruction Decoder CPU Controller
Interruptsignals
ControlFSM
Control signals
tristate buf
Arithmetic- Logic Unit
PC
Bus tomemorysystem I/O ports
A
ALU
mux
B

mux
mux
Datapath
mux
Writeports
Read ports
Registers
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3.3 Generations of Progress
Table 3.2 The 5 generations of digital
computers, and their ancestors.
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ENIAC (1946)

• Electronic Numerical Integrator And Computer
• Eckert and Mauchly
• University of Pennsylvania
• Proposed to develop a computer for the
  calculation of Trajectory tables for weapons
  during WWII (Army Ballistics Research Laboratory)
• Started 1943
• Finished 1946
• Too late for war effort
• Used to help determine feasibility of H-bomb
• Used until 1955

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ENIAC some details

• Decimal (not binary!)
• Its memory contained 20 accumulators of 10
  digits.
• 10 vacuum tubes represented each digit.
• Programmed manually by switches
• 18,000 vacuum tubes
• 30 tons
• 1500 square feet
• 140 kW power consumption
• 5,000 additions per second

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Princeton IAS Computer (1952)
Smithsonian Image 95-06151
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Commercial Computers

• 1947 Eckert-Mauchly developed their own
  Computer Corporation
• UNIVAC I (Universal Automatic Computer)
• Designed to perform mainly scientific
  calculations (e.g. US Bureau of Census 1950
  calculations)
• Became part of Sperry-Rand Corporation
• Late 1950s - UNIVAC II
• Faster
• More memory

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Early IBM computers

• Punched-card processing equipment
• 1953 - the 701
• IBMs first stored program computer
• Scientific calculations
• 1955 - the 702
• Business applications
• Lead to 700/7000 series

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Transistors

• The second generation of technology Transistors
  replaced vacuum tubes
• Smaller
• Cheaper
• Less heat dissipation
• Solid State device
• Made from Silicon (from sand)
• Invented 1947 at Bell Labs
• William Shockley et al.
• Discrete components

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IBM 360 (1964)
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IBM 360 series

• Introduced in 1964
• Replaced ( not compatible with) 7000 series
• First planned family of computers
• Similar or identical instruction sets
• Similar or identical O/S
• Increasing speed
• Increasing number of I/O ports (i.e. more
  terminals)
• Increased memory size
• Increased cost
• Multiplexed switch structure

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DEC PDP-8 (1964)

• Also introduced in 1964
• First minicomputer
• Did not need room w. A/C
• Small, could sit on a lab bench
• Relatively cheap 16,000
• Compared to 100k for IBM 360
• Embedded applications Original Equipment
  Manufacturers (OEM) allowed users to buy PDP-8
  machines and integrate them into a total system
  for resale.

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IC Production and Yield
Figure 3.8 The manufacturing process for an
IC part.
 
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Effect of Die Size on Yield
Figure 3.9 Visualizing the dramatic decrease
in yield with larger dies.
Die yield def (number of good dies) / (total
number of dies) Die yield Wafer yield ? 1
(Defect density ? Die area) / aa Die cost
(cost of wafer) / (total number of dies ? die
yield) (cost of wafer) ? (die area / wafer
area) / (die yield)
 
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3.4 Processor and Memory Technologies
Figure 3.11 Packaging of processor, memory,
and other components.
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Moores Law
Figure 3.10 Trends in processor performance
and DRAM memory chip capacity (Moores law).
 
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Device Size Scaling Trends
Based on ITRS 97-03 roadmaps
(1 µm)
Virus
Protein molecule
Naïve linear extrapolations
Effective gate oxide thickness
DNA/CNT radius
Silicon atom
Hydrogen atom
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Trend of Min. Transistor Switching Energy
Based on ITRS 97-03 roadmaps
fJ
Node numbers(nm DRAM hp)
Practical limit for CMOS?
aJ
Naïve linear extrapolation
zJ
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Pitfalls of Computer Technology Forecasting
DOS addresses only 1 MB of RAM because we cannot
imagine any applications needing more.
Microsoft, 1980 640K ought to be enough for
anybody. Bill Gates, 1981 Computers in the
future may weigh no more than 1.5 tons. Popular
Mechanics I think there is a world market for
maybe five computers. Thomas Watson, IBM
Chairman, 1943 There is no reason anyone would
want a computer in their home. Ken Olsen, DEC
founder, 1977 The 32-bit machine would be an
overkill for a personal computer. Sol Libes,
ByteLines
 
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3.5 Input/Output and Communications
Figure 3.12 Magnetic and optical disk memory
units.
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Communication Technologies
Figure 3.13 Latency and bandwidth
characteristics of different classes of
communication links.
 
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3.6 Software Systems and Applications
Figure 3.15 Categorization of software, with
examples in each class.
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High- vs Low-Level Programming
Figure 3.14 Models and abstractions in
programming.