1. Part I Background and Motivation
June 2005
Computer Architecture, Background and Motivation

2. 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 isn’t 2 as fast as a 1 GHz model)
Topics in This Part
Chapter 1 Combinational Digital Circuits
Chapter 2 Digital Circuits with Memory
Chapter 3 Computer System Technology
Chapter 4 Computer Performance
June 2005
Computer Architecture, Background and Motivation

3. 3 Computer System Technology
Interplay between architecture, hardware, and software
Architectural innovations influence technology
Technological advances drive changes in architecture
Topics in This Chapter
3.1 From Components to Applications
3.2 Computer Systems and Their Parts
3.3 Generations of Progress
3.4 Processor and Memory Technologies
3.5 Peripherals, I/O, and Communications
3.6 Software Systems and Applications
June 2005
Computer Architecture, Background and Motivation

4. 3.1 From Components to Applications
Figure Subfields or views in computer system engineering.
June 2005
Computer Architecture, Background and Motivation

5. What Is (Computer) Architecture?
Figure Like a building architect, whose place at the engineering/arts and goals/means interfaces is seen in this diagram, a computer architect reconciles many conflicting or competing demands.
June 2005
Computer Architecture, Background and Motivation

6. 3.2 Computer Systems and Their Parts
Figure The space of computer systems, with what we normally mean by the word “computer” highlighted.
June 2005
Computer Architecture, Background and Motivation

7. Price/Performance Pyramid
Differences in scale,
not in substance
Figure Classifying computers by computational power and price range.
June 2005
Computer Architecture, Background and Motivation

8. Automotive Embedded Computers
Figure Embedded computers are ubiquitous, yet invisible. They are found in our automobiles, appliances, and many other places.
June 2005
Computer Architecture, Background and Motivation

9. Personal Computers and Workstations
Figure 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?
June 2005
Computer Architecture, Background and Motivation

10. 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)
Input Systems
Controller
Memory
Datapath (regs., ALU)
Output Systems
Processor (CPU)
I/O systems

11. Inside the CPU (a more detailed look)
Block diagram of a simple, generic CPU:
CPU
Interrupt signals
Instruction Decoder & CPU Controller
Control FSM
Control signals
tristate
buf
Arithmetic Logic Unit PC
Bus to memory system & I/O ports A
ALU
mux B …
mux
mux
Data path
mux
Write ports
Registers
Read
ports

12. 3.3 Generations of Progress
Table The 5 generations of digital computers, and their ancestors.
Generation (begun)
Processor technology
Memory innovations
I/O devices introduced
Dominant look & fell
0 (1600s)
(Electro-) mechanical
Wheel, card
Lever, dial, punched card
Factory equipment
1 (1950s)
Vacuum tube
Magnetic drum
Paper tape, magnetic tape
Hall-size cabinet
2 (1960s)
Transistor
Magnetic core
Drum, printer, text terminal
Room-size mainframe
3 (1970s)
SSI/MSI
RAM/ROM chip
Disk, keyboard, video monitor
Desk-size mini
4 (1980s)
LSI/VLSI
SRAM/DRAM
Network, CD, mouse,sound
Desktop/ laptop micro
5 (1990s)
ULSI/GSI/ WSI, SOC
SDRAM, flash
Sensor/actuator, point/click
Invisible, embedded
June 2005
Computer Architecture, Background and Motivation

13. Electronic Numerical Integrator And Computer Eckert and Mauchly
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

14. 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

15. Princeton IAS Computer (1952)
Smithsonian Image

16. 1947 – Eckert-Mauchly developed their own Computer Corporation
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

17. Punched-card processing equipment 1953 - the 701
Early IBM computers
Punched-card processing equipment
the 701
IBM’s first stored program computer
Scientific calculations
the 702
Business applications
Lead to 700/7000 series

18. 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

19. IBM 360 (1964)

20. Replaced (& not compatible with) 7000 series
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

21. Small, could sit on a lab bench Relatively cheap: $16,000
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.

22. IC Production and Yield
Figure The manufacturing process for an IC part.
June 2005
Computer Architecture, Background and Motivation

23. Effect of Die Size on Yield
Figure 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) / a]–a
Die cost = (cost of wafer) / (total number of dies  die yield)
= (cost of wafer)  (die area / wafer area) / (die yield)
June 2005
Computer Architecture, Background and Motivation

24. 3.4 Processor and Memory Technologies
Figure Packaging of processor, memory, and other components.
June 2005
Computer Architecture, Background and Motivation

25. Computer Architecture, Background and Motivation
Moore’s Law
Figure Trends in processor performance and DRAM memory chip capacity (Moore’s law).
June 2005
Computer Architecture, Background and Motivation

26. 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

27. 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

28. 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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Computer Architecture, Background and Motivation

29. 3.5 Input/Output and Communications
Figure Magnetic and optical disk memory units.
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Computer Architecture, Background and Motivation

30. Communication Technologies
Figure Latency and bandwidth characteristics of different classes of communication links.
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Computer Architecture, Background and Motivation

31. 3.6 Software Systems and Applications
Figure Categorization of software, with examples in each class.
June 2005
Computer Architecture, Background and Motivation

32. High- vs Low-Level Programming
Figure Models and abstractions in programming.
June 2005
Computer Architecture, Background and Motivation