53425计算机科学概论原书chapter.pptxVIP

Chapter 1The Big PictureChapter GoalsDescribe the layers of a computer systemDescribe the concept of abstraction and its relationship to computingDescribe the history of computer hardware and softwareDescribe the changing role of the computer userDistinguish between systems programmers and applications programmersDistinguish between computing as a tool and computing as a discipline25Computing SystemsComputing systems are dynamic! What is the difference between hardware and software?2Computing SystemsHardware The physical elements of a computing system (printer, circuit boards, wires, keyboard…)Software The programs that provide the instructions for a computer to execute3Layers of a Computing System4AbstractionAbstraction A mental model that removes complex detailsThis is a key concept. Abstraction will reappear throughout the text – be sure you understand it! 5Internal ViewAbstract ViewHistoryEarly History of ComputingAbacus An early device to record numeric valuesBlaise Pascal Mechanical device to add, subtract, divide multiplyJoseph Jacquard Jacquard’s Loom, the punched cardCharles BabbageAnalytical Engine6Early History of ComputingAda LovelaceFirst Programmer, the loopAlan TuringTuring Machine, Artificial Intelligence TestingHarvard Mark I, ENIAC, UNIVAC IEarly computers launch new era in mathematics, physics, engineering and economics 7First Generation Hardware (1951-1959)Vacuum TubesLarge, not very reliable, generated a lot of heatMagnetic Drum Memory device that rotated under a read/write headCard Readers ? Magnetic Tape DrivesSequential auxiliary storage devices8Second Generation Hardware (1959-1965)TransistorReplaced vacuum tube, fast, small, durable, cheapMagnetic CoresReplaced magnetic drums, information available instantlyMagnetic DisksReplaced magnetic tape, data can be accessed directly9Third Generation Hardware (1965-1971)Integrated CircuitsReplaced circuit boards, smaller, cheaper, faster, more reliable TransistorsNow used for memory constructionT