高等计算机系统结构引论（第一讲）程旭2014年2月17日教材与教师主要教材：Computer Architecture: A Quantitative Approach,4th(2006) or 5th Edition (2012) ，Patterson and Hennessy 主讲教师：程旭北京大学微处理器研究开发中心刘先华北京大学微处理器研究开发中心助教：TBD授课时间地点：每周一下午 15:10—18:00 二教203学习和把握将决定二十一世纪计算机具体形态的设计技术、机器结构、工艺要素、评价方法等技术工艺编程语言操作系统历史应用软硬件界面设计(ISA)测度 和 评测并行性计算机系统结构 •指令系统设计 •组成 •硬件学习和把握将决定二十一世纪计算机具体形态的设计技术、机器结构、工艺要素、评价方法等技术工艺Programming modelsBusiness models历史应用Architectural Design Patterns测度 和 评测计算机系统结构•计算机应用需要什么？•操作系统需要那些功能支持? •优化编译可以利用和实现哪些功能?•我们能够建造什么样的机器? •今后的计算机将会怎样?°计算机系统结构研究人员必须具有宽厚的专业知识!计算机基础数字逻辑计算机组织与结构 操作系统 编译技术数据结构 应用基础 C 语言编程存储管理 调度 并发代码生成 优化基本逻辑单元 处理器基础知识本课程在教学安排中的地位高等计算机体系结构如何实现！ 具体细节---知其然！1.分析+评测—知其所以然！2.并行计算机系统结构计算机设计领域的剧变°Most of last 50 years, Moore’s Law ruled•Technology scaling allowed continual performance/energy improvements without changing software model°Last decade, technology scaling slowed/stopped•Dennard scaling over (supply voltage ~fixed) •Moore’s Law (cost/transistor) over?•No competitive replacement for CMOS anytime soon •Energy efficiency constrains everything°No “free lunch” for software developers, must consider:•Parallel systems•Heterogeneous systems当今主流的目标系统°Mobile (smartphone/tablet)•>1 billion sold/year•Market dominated by ARM-ISA-compatible general-purposeprocessor in system-on-a-chip (SoC)•Plus sea of custom accelerators (radio, image, video,graphics, audio, motion, location, security, etc.)°Warehouse-Scale Computers (WSCs)•100,000’s cores per warehouse•Market dominated by x86-compatible server chips•Dedicated apps, plus cloud hosting of virtual machines•Starting to see some GPU usage, but mostly general-purpose CPU code°Embedded computing•Wired/wireless network infrastructure, printers•Consumer TV/Music/Games/Automotive/Camera/MP3Charles Babbage (1791-1871)°Lucasian Professor ofMathematics, CambridgeUniversity, 1828-1839°A true “polymath” withinterests in many areas°Frustrated by errors inprinted tables, wanted tobuild machines to evaluateand print accurate tables°Inspired by earlier workorganizing human“computers” to methodicallycalculate tables by hand [Copyright expired and in public domain.Image obtained from Wikimedia Commons.]Charles Babbage°Difference Engine 1823°Analytic Engine 1833•The forerunner of modern digital computer!Application–Mathematical T ables – Astronomy–Nautical T ables – NavyBackground–Any continuous function can be approximated by apolynomial --- WeierstrassTechnology–mechanical - gears, Jacquard’s loom, simple calculatorsDifference EngineA machine to compute mathematical tablesWeierstrass:•Any continuous function can be approximated by a polynomial •Any polynomial can be computed from difference tablesAn examplef(n) = n2 + n + 41d1(n) = f(n) - f(n-1) = 2nd2(n) = d1(n) - d1(n-1) = 2f(n) = f(n-1) + d1(n) = f(n-1) + (d1(n-1) + 2)all you need is an adder!n d2(n) d1(n) f(n)41122232424 6 843 47 53 61Babbage’s Difference Engine 1 1832Analytic Engine1833: Babbage’s paper was published•conceived during a hiatus in the development of the difference engineInspiration: Jacquard Looms•looms were controlled by punched cards-The set of cards with fixed punched holesdictated the pattern of weave program-The same set of cards could be used withdifferent colored threads numbers1871: Babbage dies•The machine remains unrealized.It is not clear if the analytic engine could be built even today using only mechanical technologyBabbage’s Difference Engine 2 andAnalytical Engine1834 Babbage Analytical EngineThe Mill The Store PrinterPunchOperation Cards Variable CardsProgramBabbage Analytical Engine•The Store: Memory unit consisting of counter wheels•The Mill: The arithmetic unit capable of 4 operations used a pair of register and produced results stored in another register in the store•Operation Cards: Specified one of Four operations •Variable Cards: Specified the memory location to be used•Output: Printer or punchAnalytic EngineThe first conception of a general-purpose computer1.The store in which all variables to be operated upon,as well as all those quantities which have arisenfrom the results of the operations are placed.2.The mill into which the quantities about to beoperated upon are always brought.The programOperation variable1 variable2 variable3An operation in the mill required feeding two punched cardsand producing a new punched card for the store.An operation to alter the sequence was also provided!The first programmerAda Byron aka“Lady Lovelace” 1815-52Ada’s tutor was Babbage himself!While not using the practical technology of the era, Alan Turing developed the idea of a "Universal Machine" capable of executing anydescribable algorithm, and forming the basis for the concept of "computability". Perhaps more importantly Turing's ideas differed from those of others who were solving arithmetic problems by introducing the concept of "symbol processing".1937, Alan Turing第一台通用电子计算机--ENIAC 1946年2月14日Electronic Numerical Integrator and CalculatorJ. Presper Eckert&John MauchlyMoore SchoolUniversity of PennsylvaniaSize: 80 feet long8.5 feet high18,000 vacuum tubes5000 additions/sec.The world’s first general-purpose electronic computerconditional Jump and be programmable, distinguished it from earlier ones Used for computing artillery firing tablesAccumulator°28 vacuum tubesWW-2 EffortENIAC’S Application: Ballistic calculationsangle = f (location, tail wind, cross wind,air density, temperature, weight of shell,propellant charge, ... )ENIAC was NOT a “stored program” device °For each problem, someone analyzed the arithmetic processing needed and prepared wiring diagrams for the computors to use when wiring the machine°Process was time consuming and error prone °Cleaning personnel often knocked cables out of their place and just put them back somewhereWiring the machineElectronic Discrete Variable Automatic Computer (EDVAC)°ENIAC’s programming system was external•Sequences of instructions were executed independently of the results of the calculation•Human intervention required to take instructions “out of order”°Eckert, Mauchly, John von Neumann and others designed EDVAC (1944) to solve this problem•Solution was the stored program computer“program can be manipulated as data”°First Draft of a report on EDVAC was published in 1945, but just had von Neumann’s signature!•In 1973 the court of Minneapolis attributed the honor of inventing the computer to John Atanasoff“ ”The von Neumann MachineStored Program ComputerIAS(Institute for Advanced Study)Computer1946Main Memory ArithmeticLogicUnitProgramControlUnitI/OEquipment存储程序的思想即构成计算机程序的指令可同数据一样事先存放到存储器中，然后由计算机自己一条条取出执行。
