Chapter 1 Computer Abstraction and Technology

1. Chapter 1Computer Abstraction and Technology

2. Introduction • This course is all about how computers work • The third revolution for civilization • Faster computers have made applications (science fiction) that were economically infeasible suddenly become practical • Automatic teller machine (ATM) • Computers in automobiles • Laptop • Human genome project • WWW

3. Introduction • But what do we mean by a computer? • Different types: desktop, servers, embedded devices • Different uses: automobiles, graphics, finance, genomics… • Different manufacturers: Intel, Apple, IBM, Microsoft, Sun… • Different underlying technologies and different costs! • Analogy: Consider a course on “automotive vehicles” • Many similarities from vehicle to vehicle (e.g., wheels) • Huge differences from vehicle to vehicle (e.g., gas vs. electric) • Best way to learn: • Focus on a specific instance and learn how it works • While learning general principles and historical perspectives

4. Processors sold in 1998-2002 Embedded CPU: CPU core

5. What you can learn? • How are programs in high-level language (C or Java), translated into hardware language and how hardware executes it? • What is the interface between S/W and H/W, and how does S/W instruct the H/W to perform needed functions? • What determines the performance of a program, and how can a programmer improve performance? • What techniques can be used by hardware designers to improve performance?

6. Why learn this stuff? • You want to call yourself a “computer scientist” • You want to build software people use (need performance) • You need to make a purchasing decision or offer “expert” advice • Both Hardware and Software affect performance: • Algorithm determines number of source-level statements and I/O operations executed • Language/Compiler/Architecture determine # of machine instructions for each source statement (Chapter 2 and 3) • Processor/Memory determine how fast instructions are executed (Chapter 5, 6, and 7) • I/O system (hardware and OS) determines how fast is I/O • Assessing and Understanding Performance in Chapter 4

7. What is a computer? • 5 Components: • input (mouse, keyboard) • output (display, printer) • memory (disk drives, DRAM, SRAM, CD) • the processor (datapath and control): Our primary focus: • implemented using millions of transistors • Impossible to understand by looking at each transistor • Or include Network

8. Inside processor chip

9. PC Board

10. Abstraction • Delving into the depths reveals more information • An abstraction omits unneeded detail, helps us cope with complexityWhat are some of the details that appear in these familiar abstractions?

11. How do computers work? • Need to understand abstractions such as: • Applications software • Systems software • Assembly Language • Machine Language • Architectural Issues: i.e., Caches, Virtual Memory, Pipelining • Sequential logic, finite state machines • Combinational logic, arithmetic circuits • Boolean logic, 1s and 0s • Transistors used to build logic gates (CMOS) • Semiconductors/Silicon used to build transistors • Properties of atoms, electrons, and quantum dynamics • So much to learn!

12. Why not simply write code in assembly? • Why not simply convert HLL statements into bits for the hardware to interpret?

13. The role of the compiler • The compiler translates a HLL program into the machine language for the given ISA • Compilers allow software developers to work at the HLL level without worrying about low-level details of the underlying machine • The compiler writer’s first responsibility is to ensure that the machine language program • Exactly matches the functionality of the HLL program • Exactly conforms to the ISA specification • Compiler product differentiators include • Speed of code execution on the hardware • Code density (reduces memory requirements) • Compilation speed (how long from HLL to machine code) • Debugging capabilities

14. Instruction Set Architecture • A very important abstraction • interface between hardware and low-level software • standardizes instructions, machine language bit patterns, etc. • advantage: different implementations of the same architecture • disadvantage: sometimes prevents using new innovationsTrue or False: Binary compatibility is extraordinarily important? • Modern instruction set architectures: • IA-32, PowerPC, MIPS, SPARC, ARM, and others

15. Instruction Set Architecture software instruction set hardware

16. What is Computer Architecture? Computer Architecture = Instruction Set Architecture + Machine Organization

17. What is Computer Architecture? Application Operating System Compiler Firmware Instruction Set Architecture Instars. Set Proc. I/O system Datapath & Control Digital Design Circuit Design Layout

18. The ISA and computer hardware • The designer of computer hardware (CPU, caches, MM, and I/O) must first ensure that the hardware correctly executes the machine code specified in the ISA spec • Hardware product differentiators include • Performance (emphasis of this course) • Power dissipation (a huge issue today!) • Cost (die size, package pin count, cooling costs) • Reliability, availability, serviceability • Ability to upgrade

19. Software and hardware Central Processing Unit instructions operands Level1 Data Cache Level1 Instruction Cache Level2 Cache Interconnect disk keyboard/mouse Main Memory Input/ Output network etc

20. Historical Perspective • ENIAC built in World War II 1943 was the first general purpose computer • Used for computing artillery firing tables • 80 feet long by 8.5 feet high and several feet wide • Each of the twenty 10 digit registers was 2 feet long • Used 18,000 vacuum tubes • Performed 1900 additions per second • Programming manually by plugging cables and setting switches • Since then:Moore’s Law: transistor capacity doubles every 18-24 months • http://www.intel.com/research/silicon/mooreslaw.htm

21. Historical Perspective • By W. Shockley, J. Bardeen, W. Brattain of Bell Lab. in 1947 • Much more reliable than vacuum tubes • Electronic switches in “solids”

22. Historical Perspective • 1950

23. Historical Perspective • 1971年第一個微處理器：Intel 4004 108 KHz, 0.06 MIPS 2300 transistors (10 microns) Bus width: 4 bits Memory: 640 bytes For Busicom calculator

24. Historical Perspective • 1977年Apple II: Steve Jobs, Steve Wozniak

25. Historical Perspective • 1981年IBM PC: Intel 8088, 4.77MHz

26. Historical Perspective • 1979: 1st electronic spreadsheet (VisiCalc for Apple II) by Don Bricklin and Bob Franston “The kill app for early PCs” Followed by dBASE II, ...

27. Historical Perspective • 1980s • New processor architectures were introduced: • RISC (Reduced Instruction Set Computer) IBM: John Cocke UC Berkeley: David Patterson Stanford: John Hennessy • Commercial RISC processors introduced around 1985 􀁺 MIPS: MIPS Sun : Sparc IBM : Power RISC HP : PA-RISC DEC : Alpha • They compete with CISC (complex instruction set computer) processors, mainly Intel x86 processors, for the next 15 years

28. Performance

29. Factor for improvement • Several factors: IC technology: clock rate, power, transistors per chip • Computer architecture: pipeline, cache, MMX, instructions per cycle • Mass market: market share, revenue, applications

31. VLSI Tech

32. Technology Trends: Memory Capacity(1 Chip DRAM) year size(Mbit) 1980 0.0625 1983 0.25 1986 1 1989 4 1992 16 1996 64 2000 256 1.4X/yr, or doubling every 2 years 4000X since 1980

33. Technology Trends:Microprocessor Capacity

34. Moore’s law

35. Make it into conductor: • diffuse, bombard ions • Make it into insulator: silicon oxide (glass) • Make it into switch: transistor

36. Semiconductor Processing

37. Fallacies and Pitfalls • Fallacy (wrong belief): Computers have been built in the same, old-fashioned way for too long, and this antiquated model of computation is running out of steam. • Pitfall (easily made mistake): Ignoring inexorable progress of hardware when planning a new system.