Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 201-1Computers: A First Look•In this lecture:–Syllabus–Course overview–What is a computer?–Why computers?–What are some characteristics of different types of computers?–Explain the relationship between hardware and software–Basic anatomy of a computer.1-2What will you learn?–How computers internally represent the data you give them–How memory and various hardware components work–How programs make the computer do our bidding–What operating systems do (to make our lives easier)–How to program (toy examples)–How computer networks work–How the Internet works–What hacking and computer security is all about–What can we learn about computers from video games–Computer Graphics–Artificial Intelligence –Ethics and legality in the digital millennium1-3What is a computer?•What is a computer?–by example•Laptop computers•Video Game Consoles•Internet Routers•ATM machines•Personal Video Recorders (Tivo, etc)•GPS•Alarm clocks•Microwaves•Coffee makers1-4What is a computer?•Computers are tools; we use them to perform tasks that:–are repetitive–involve calculation –involve storage/retrieval of large quantities of information–…–They’re useful!•Why learn about computers?–They are ubiquitous–You're curious?1-5What Is a Computer ?•Definition:–A computer is a processor –it takes data in one form, uses it, and produces a different form of information which is related to (but not the same as) the original data.•Using this broad definition, many things we wouldn’t usually consider computers qualify. . .inputoutputprocessing1-6What Is (and Isn’t) a Computer•A calculator ?–Input : –Processing :–Output :1-7What Is (and Isn’t) a Computer•The Abacus?–an early “calculation” device that holds numbers for the user•Input : •Processing :•Output :1-8What Is (and Isn’t) a Computer•A mechanical bathroom scale ?–Input : –Processing : –Output :1-9What Is (and Isn’t) a Computer•A speedometer ?–Input : –Processing : –Output :1-10The Many Kinds of Computers•Computers can also be classified by compositional characteristics:ElectronicVs.MechanicalDigitalVs.AnalogGeneral-purposeVs.Special-purpose1-11Purpose•Special-purpose Computers–Manufactured to perform a predetermined task or set of tasks.–Some special purpose computers?•Often attached to sensor to measure and/or control the physical environment • examples?•General-purpose Computer–Was not manufactured to do any one thing.–Changeable to do any task.–(read: programmable)• examples?General-purposeVs.Special-purpose1-12Power•Electronic Computer–Needs an electrical source to function.–Constructed from transistors and electrical circuits•Mechanical Computer–Produces its own intrinsic energy. •[Does not need electricity to function.] –Constructed of a combination of gears, levers and/or springs.ElectronicVs.Mechanical1-13Analog Vs Digital•Digital (Computer)–One that functions in discretely varying quantities.–Produces or gives results that are also discretely varying.•Digital devices include:–A toggle (on/off) light switch–A traffic light–StairsDigitalVs.Analog1-14Analog Vs Digital•Analog (Computer)–One that functions in continuously varying quantities.–Produces or gives results that are also continuously varying.•Analog devices include:–A dimmer light switch–A ramp–Acceleration pedal in a car•Is digital data inherently better than analog data? Why would we make a computer digital or analog? Pros? Cons?DigitalVs.Analog1-15Deciding Analog vs. Digital•General Purpose means its tasks may be changed–We intend to build a physical device that can be used for many different purposes.•Computers are composed of binary circuitry... –Binary is a subset of Digital; •it has only two possible conditions (on/off == true/false)•Binary circuits requires a source of electricity to function; hence these computers will also be electric.•why binary ?1-16The G-P,E,D Computer•Binary circuitry provides a means for physically representing and evaluating basic logical expressions (boolean logic)–the circuitry is adaptable such that we can represent different logic with the same physical circuitry!•read: programmable/general purpose–on top of very simple logic we will build more complicated things1-17The G-P,E,D Computer•Computer Hardware–The electronics and associated mechanical parts of the computer.–the hardware is capable of performing various tasks, as we instruct it•Computer Software–The instructions that control the hardware and cause the desired tasks to occur on the hardware–A disk is considered hardware. –A program on the disk is considered software.–A computer needs the hardware to take instructions, as well the means to take input, process it, and produce output.1-18The Composition of a Computer•von Neumann Architecture (1946)•A “stored-program” computer requires the following hardware1. Input Units: a means to obtain data2. Primary Memory: a place to store . . .–Program: …the current list of instructions–Data: …any input, output, or scrap work 3. CPU: a means to act on the list of instructions4. Output Units: a means to produce resultsCPUInputUnitsOutputUnitsMemory1-19The Composition of a Computer•Input & Output units allow us to communicate with the computer.•Memory will store the instructions to be run as well as any data we might need in order to generate the result.•The CPU is capable of executing a limited number of very simple instructions that are read from memory–The CPU can also read from and write to the data portion of memory–the instructions are simple, but can be combined to build more complicated operations•A collection of such instructions comprise a program–a computer can do “anything” provided we have a precise way to describe the task in these simple operations1-20In the future, there will be robots•In 1965 Moore’s Law predicted that the computing power (speed) of a silicon chip of the same size would double every 18 months–(has been remarkably accurate, and still is)–What does this mean?•Physical limits to computer speeds and sizes. . .–lead to investigation, perhaps adoption other methods of