CHAPER 4 COMPUTER SOFTWARE Oleh : Kundang K Juman

Learning Objectives Differentiate between the two major types of software Describe the general functions of the operating system Differentiate among the three types of operating systems and describe each type Identify three methods for developing application software Describe the major types of application software Explain how software has evolved and its future evolution Describe enterprise software

Chapter Overview Software History and Significance The Software Crisis Software Fundamentals Systems Software System Control Programs System Support Application Software Types of Application Software Types of Personal Application Software Suites Software Issues evaluation and Selection Software Licensing Software Upgrades Shareware, Freeware, and Cheapware Open Systems Programming Languages Machine Language Assembly Language Procedural Languages Nonprocedural Languages Natural Programming Language Visual Programming Language Hypertext Markup Language Virtual Reality Modelling Language Object-Oriented Programming Language Enterprise Software Streamlining Organizational SAP

Case: The IRS and the Millennium Bug The Problem Y2K problem has resulted from the high cost of mainframe computations and data storage in the 1950s and 1960s complex structure makes it almost impossible for the IRS to be Y2K compliant in time agency changed its software in response to changes in the tax code

Case (continued…) The Solution The Results IRS has spent more than $4 billion over the past decade to modernize its computer systems the agency has $1 billion dollars and 600 people dedicated to the Y2K project The Results no one will know until well into the year 2000

Case (continued…) What have we learned from this case?? Failure to budget for continuing maintenance of software programs can have devastating results One programmer cannot begin with his portion of the problem until he receives another completed portion form someone else, as this other part or “module” may define the inputs or outputs that his own part must deal with

Software History and Significance When the first applications of computers in business were introduced in the early 1950s, software was less important (and less costly) in computer systems Today, software comprises a much larger percentage of the cost of modern computer systems The Software Crisis no software applications fast enough to keep up with rapidly changing business conditions and rapidly evolving technologies not only must new applications be developed quickly, but existing software must also be maintained increasing complexity, leads to the increased potential for “bugs” testing and “debugging” software is expensive and time-consuming

Software History and Significance (continued …) Software Fundamentals computer programs - sequences of instructions for the computer programming - process of writing (or coding) programs programmers - individuals who perform programming

System Software System software the class of programs that control and support the computer system and its information processing activities facilitates the programming, testing, and debugging of computer programs usually independent of any specific type of application support application software by directing the basic functions of the computer

System Software (continued …) System Control Program programs that control the use of the hardware, software and data resources of a computer system operating system (main system control program) supervises the overall operation of the computer, including monitoring the computer’s status and scheduling operations, which include controlling the input and output processes allocates CPU time and main memory to programs running on the computer, and also provides an interface between the user and the hardware

System Software (continued …) System Control Program (continued …) Process management managing the program or programs running on the processor at a given time Multitasking (or multiprogramming) managing two or more tasks, programs, running on the computer system at the same time Time-sharing a number of users operate on-line with the same CPU, but each uses a different input/output terminal

System Software (continued …) System Control Program (continued …) Multithreading a form of multitasking that focuses on running multiple tasks within a single application simultaneously Multiprocessing a computer system with two or more processors that can run more than one program or thread at a given time by assigning them to different processors Virtual memory simulates more main memory than actually exists in the computer system

System Software (continued …) System Control Program (continued …) File Management and Security managing the arrangement of, and access to, files held in secondary storage Fault Tolerance the ability of a system to produce correct results and continue to operate even in the presence of faults or errors Graphical User Interface (GUI) allows users to have direct control of visible objects and actions that replace complex command syntax

System Software (continued …) System Control Program (continued …) Major Desktop Operating Systems MS-DOS Windows 3.xx Windows 98 Windows 95 Windows NT Windows 2000 Windows CE IBM’s OS/2 Macintosh Operating System UNIX Java Operating System (JavaOS)

System Software (continued …) System Control Program (continued …) Major Departmental Sever Operating System UNIX, Windows NT Server, IBM’s OS/2 Warp Server, Novell NetWare, and IBM’s OS/400 Major Enterprise Operating Systems IBM’s MVS (Multiple Virtual Storage), IBM’s VM (Virtual Machine), IBM’s VSE (Virtual Storage Extended), and Digital Open VMS (Virtual machine System)

System Software (continued …) System Support Programs System support programs support the operations, management, and users of a computer system System utility programs accomplish common tasks such as sorting records, checking the integrity of diskettes, creating directories and subdirectories, restoring accidentally erased files, locating files within the directory structure, managing memory usage, and redirecting output

System Software (continued …) System Support Programs (continued …) System performance monitors monitor the processing of jobs on a computer system and produce reports containing detailed statistics concerning the use of system resources System security monitors monitor the use of a computer system to protect it and its resources from unauthorized use, fraud, or destruction

Application Software Application Software instructions that direct a computer system to perform specific information processing activities and provide functionality for users Types of Application Software Proprietary application software addresses a specific or unique business need for a company Off-the-shelf application software developed programs sold to many organizations may be customizable or may be standard package

Application Software (continued …) Personal Application Software one of the off-the-shelf application programs that are not linked to any specific business function, but instead support general types of processing Data management Encompassing spreadsheet Desktop publishing Publishing Word processing Communications Graphics Multimedia GroupWare Speech recognition software

Application Software (continued …) Software Suites collections of application software packages that integrate the functions of the packages examples : Microsoft Office, Novell Perfect Office, and Lotus SmartSuite generally include : a spreadsheet program, word processor, database program, and graphics package with the ability to move document, data. And diagrams among them

Software Issues Software Selection Selection factors size and location of the current and future user base system administration tools initial and subsequent costs current and future system capabilities existing computing environment in-house technical skills

Software Issues (continued …) Software Evaluation evaluation checklist ease of use in development learning maintenance reporting capability graphic presentation general functionality data handling output options performance security environments and hardware documentation vendor support

Software Issues (continued …) Software Licensing copyright - exclusive legal right to reproduce, publish, and sell the software licenses - permission granted under the law to engage in an activity otherwise unlawful Software Upgrades revised software may offer valuable enhancements but may offer little in terms of additional capabilities revised software may contain bugs

Software Issues (continued …) Shareware, Freeware, and Cheapware Shareware - low price software Freeware - free copyrighted software Cheapware - free public-domain software Open Systems a paradigm of computing products that work together use the same operating system with compatible software on all the different computers in a system to empower designers to choose the best computer hardware, operating system, and application software

Programming Languages Machine Language (first generation of programming languages) the lowest level computer language composed of binary digits all other languages are translated into machine language before the computer can run the instructions Assembly Language (second generation of computer languages) a lower-level but more user-friendly language assembler - translates an assembly language program into machine language … .. ……

Programming Languages (continued …) Procedural Languages (third generation languages) much closer to natural language use common words rather than abbreviated mnemonics compiler - translates the entire program at once interpreter - translates and executes one source program statement at a time

Programming Languages (continued …) Nonprocedural Language (fourth generation languages) a high-level language allows the user to specify the desired result without having to specify the detailed procedures needed for achieving the result can be used by non technical users Natural Language programming Languages (fifth generation languages) translates natural languages into a structured, machine-readable from are extremely complex

Programming Languages (continued …) Visual Programming Languages used within a graphical environment example : Visual Basic and Visual C++ popular to non technical users Hypertext Markup Language (HTML) standard language used in World Wide Web contains text, images, and other types of information such as data files, audio, video, and executable computer programs

Programming Languages (continued …) Virtual Reality Modeling Language (VRML) a file format for describing three-dimensional interactive worlds and objects can be used with the World Wide Web Object-Oriented Programming Languages (OOP) based on the idea of taking a small amount of data and the instructions about what to do with that data and putting both of these together into what is called an object

Enterprise Software Difficulty in Most Organizations the sheer complexity that arises from all the different types of hardware and software that they use Package Wanted by an Organization support integration between functional (i.e., human resource, operations, marketing, finance, accounting, etc.) modules be quickly changed or enhanced present a common graphical look-and-feel help to reduce training and operation costs

Enterprise Software (continued …) manages a company’s vital operations, such as supply chain management (movement of raw material from suppliers through shipment of finished goods to customers), inventory replenishment, ordering, logistics coordination, human resource management, manufacturing, operations, accounting, and financial management

Enterprise Software (continued …) System Anwendung Produket (SAP) one of the largest vendors (holds 30% of the enterprise software market) strength :  high degree of integration  support for multi-site, multi-currency operations R / 3 - flagship client/server product has a high degree of functional integration across the enterprise criticism : complex, time-consuming and expensive to install and integrate with other systems decoupling the models of R/3 into separate components, each with its own database