Part I Background and Motivation

1. Part IBackground and Motivation 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) 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 Computer Architecture, Background and Motivation

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

5. 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. Computer Architecture, Background and Motivation

6. 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. Computer Architecture, Background and Motivation

7. Price/Performance Pyramid Differences in scale, not in substance Figure 3.4 Classifying computers by computational power and price range. Computer Architecture, Background and Motivation

8. Automotive Embedded Computers Figure 3.5 Embedded computers are ubiquitous, yet invisible. They are found in our automobiles, appliances, and many other places. Computer Architecture, Background and Motivation

9. 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? 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) InputSystems Controller Memory Datapath(regs., ALU) OutputSystems Processor (CPU) I/O systems

11. 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

12. 3.3 Generations of Progress Table 3.2 The 5 generations of digital computers, and their ancestors. Computer Architecture, Background and Motivation

13. 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 95-06151

16. 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. Early IBM computers • Punched-card processing equipment • 1953 - the 701 • IBM’s first stored program computer • Scientific calculations • 1955 - 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. 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. 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 3.8 The manufacturing process for an IC part. Computer Architecture, Background and Motivation

23. 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) / a]–a Die cost = (cost of wafer) / (total number of dies  die yield) = (cost of wafer)  (die area / wafer area) / (die yield) Computer Architecture, Background and Motivation

24. 3.4 Processor and Memory Technologies Figure 3.11 Packaging of processor, memory, and other components. Computer Architecture, Background and Motivation

25. Moore’s Law Figure 3.10 Trends in processor performance and DRAM memory chip capacity (Moore’s law). 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 Computer Architecture, Background and Motivation

29. 3.5 Input/Output and Communications Figure 3.12 Magnetic and optical disk memory units. Computer Architecture, Background and Motivation

30. Communication Technologies Figure 3.13 Latency and bandwidth characteristics of different classes of communication links. Computer Architecture, Background and Motivation

31. 3.6 Software Systems and Applications Figure 3.15 Categorization of software, with examples in each class. Computer Architecture, Background and Motivation

32. High- vs Low-Level Programming Figure 3.14 Models and abstractions in programming. Computer Architecture, Background and Motivation