Java Software SolutionsBasic Computer ProcessingMemorySoftware CategoriesWhat This Means to UsMore: What this means to usAnalog versus Digital SignalsAn Analog Signal versus a Digital SignalBinary NumbersConverting Binary Numbers to Decimal NumbersHardware ComponentsPeripheralsInput/Output DevicesMain Memory and Secondary MemoryCharacteristics of Main MemorySecondary Memory DevicesTwo Other Common Terms for Memory DevicesOther Memory DevicesNetworksLocal Area Networks and Wide Area NetworksThe InternetIP Address vs Internet AddressThe Domain Name SystemThe World Wide WebHypertext and BrowsersUniform Resource LocatorsAnother Sample URLProgrammingProblem SolvingHow do these Steps Apply to You?The Java Programming LanguageReasons Why Java is PopularA Java ProgramWhat to Notice in Lincoln.javaWhat to Notice (2)The println() MethodAnother Look at Lincoln.javaThe Method Named main()CommentsTwo Types of CommentsExternal Documentation javadocGood Programming PracticesIdentifiers and Reserved WordsThe Reserved WordsReserved WordsRules for Naming IdentifiersConventions for Naming IdentifiersChoosing Identifier NamesWhite SpaceProgramming LanguagesFrom Machine Language to Assembly LanguageFrom Low-level Languages to High-level LanguagesFourth-Generation LanguagesCompilers and InterpretersEditing and Running Your ProgramTranslation of Source CodeA CompilerAn InterpreterJava Uses Both a Compiler and InterpreterThe Advantage of Java BytecodeCompiling and Executing Programs on OspreyThe Java Software Development Kit (JDK)Integrated Development Environments (IDEs)More on: Syntax and SemanticsJava SyntaxSemantics (meaning)ErrorsCompile-time and Run-time ErrorsLogical Errors1Java Software SolutionsChapter 1Computer Systems2Basic Computer ProcessingA computer system is made up of hardware and software.Hardware: Chips, keyboards, disks, etc.Software: Programs and the data those programs use.Key Components of a Computer Systemcentral processing unit (CPU)input/output (I/O) devicesmain memorysecondary memory devices3MemoryPrograms and data are held in storage devices called memory, which fall into two categories:Main MemoryThe storage device (e.g., chips on the mother board) that holds the programs and their data (software) while the programs are executing.Secondary MemoryDevices such as hard disks that store software in a relatively permanent manner.We save our software on secondary memory. Copies of the software are brought into main memory when we execute our programs.4Software CategoriesWe will be concerned with two categories of software.The operating system.Provides a user interface that allows us to interact with the machine (enter input and view output).Manages computer resources such as the CPU and main memory.Application SoftwareGeneric term for just about any software other than the operating system.Word processors, web browsers, games, business applications, etc.The focus of this course is development of high-quality application programs.5What This Means to UsWe will be learning to create application programs using the Java programming language.Initially, the hardware we will use is a computer named Osprey that is located on campus, but can be accessed from home.Our software will be the Linux operating system, one of two text editors (vi or Pico), the Java compiler (javac), and the Java interpreter (java).Other software such as communications software, etc. will be used, but will not require much interaction on our part.6More: What this means to usSomewhere around mid-semester, we will switch our supporting platform to a window’s based platform using the ‘med – editor’ Will need to download and configure this…Will need to download and configure the Java 2 Standard Edition (J2SE) and Development Kit JDK 5.0 () from Sun Microsystems.We will discuss these later, although you may wish to download and configure early…7Analog versus Digital SignalsAnalog information and/or signals are continuous, varying in direct proportion to the source of the information – like the amplitude of a wave may vary with volume. It’s period may vary with frequency…Digital technology breaks information into discrete pieces and represents the pieces as numbers.Music on a CD is stored digitally, as a series of numbers. The music is sampled about 40,000 times per second and each number represents the voltage level of one specific instance of the recording.8An Analog Signal versus a Digital Signalanalogdigital9Binary NumbersA digital computer stores information as numbers, but those numbers are not stored as decimal numbers.All information in a computer is stored and managed as binary values.The binary number system has only two digits, 0 and 1.A single binary digit is called a bit.10Converting Binary Numbers to Decimal NumbersStarting with the rightmost bit in a binary number, each position represents a power of 2, with the rightmost bit position representing 20 which is decimal 1, the next bit position representing 21 which is 2 and the next representing 22 which is 4, etc.Binary 1011 is 1* 23 or 8 + 0 * 22 or 0 + 1 * 21 or 2 + 1 * 20 or 1 which adds up to 11 decimal (base 10).Binary 11001001 is 201 decimal.CAN YOU DO THIS????In general, n bits can represent 2n unique items.Computers typically manipulate sequences of 8 bits with each sequence of 8 bits referred to as a byte.11Hardware ComponentsWe use the term computer architecture to describe how the hardware components of a computer are put together.A program and its data reside in main memory while the program runs.The Central Processing Units (CPU) reads one program instruction from main memory and executes it.(Called ‘fetch – execute’ cycle)If an instruction needs data, such as the amount in a bank account, the CPU will acquire that information from central memory (which may require the access of data in secondary memory to be brought into memory first).The process repeats until the program ends.12PeripheralsAlmost all devices in a computer other than the CPU and main memory are called peripherals.Controllers are devices that coordinate the activities of specific peripherals.A unit with several disks attached will have a disk controller for timing, contention, data access, …Input/Output (I/O) devices and secondary memory devices are considered peripherals.13Input/Output
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