b. Managing Information System Software 6.1

SOFTWARE DETAILED INSTRUCTIONS TO CONTROL COMPUTER OPERATION PROGRAM: SET OF INSTRUCTIONS TO THE COMPUTERPROGRAM: SET OF INSTRUCTIONS TO THE COMPUTER STORED: PROGRAM MUST BE IN PRIMARY STORAGESTORED: PROGRAM MUST BE IN PRIMARY STORAGE SYSTEM SOFTWARE: MANAGES COMPUTER RESOURCESSYSTEM SOFTWARE: MANAGES COMPUTER RESOURCES APPLICATION SOFTWARE: SPECIFIC BUSINESS APPLICATIONAPPLICATION SOFTWARE: SPECIFIC BUSINESS APPLICATION*

SOFTWARE HARDWARE HARDWARE OPERATING SYSTEM: SCHEDULED COMPUTER EVENTS ALLOCATES COMPUTER RESOURCES MONITORS EVENTS UTILITY PROGRAMS: ROUTINE OPERATIONSe.g. scandisk Applications and Tools Word processors, spreadsheets etc. PROGRAMMING LANGUAGES: ASSEMBLY LANGUAGE; FORTRAN; COBOL; PL / 1; QBASIC; PASCAL; C; C++; “FOURTH GENERATION” LANGUAGES SYSTEM SOFTWARE APPLICATION SOFTWARE USERUSER

OPERATING SYSTEM MANAGES & CONTROLS ACTIVITIES Provides the software foundation for the computer to operate and application programs to run.Provides the software foundation for the computer to operate and application programs to run. Allocation of memory, storage, CPU time.Allocation of memory, storage, CPU time. Interface to user e.g. GUI.Interface to user e.g. GUI. Scheduling EG. CPU, ProgramsScheduling EG. CPU, Programs Monitoring of input and output devicesMonitoring of input and output devices E.g. Unix, Windows, DOS, MAC OSE.g. Unix, Windows, DOS, MAC OS*

APPLICATIONS / TOOLS & COMPILERS Applications provide an interface between the OS / Hardware and the user.Applications provide an interface between the OS / Hardware and the user. –Generally provide the productivity –E.g. Word-processing, spreadsheets etc. Compilers produce applications.Compilers produce applications. –They convert source (English like programming) code into machine language. –E.g. C, C++, Java, Cobol, Visual Basic –Higher level languages are more English-like (Java) and low level languages are more machine language- like.

MULTIPROGRAMMING OPERATING SYSTEM UNUSED MEMORY OPERATING SYSTEM UNUSED MEMORY PROGRAM 1 PROGRAM 2 PROGRAM 3 TRADITIONAL SINGLE- PROGRAM SYSTEM MULTIPROGRAMMING ENVIRONMENT

MULTITASKING MULTIPROGRAMMING ON A SINGLE-USER SYSTEM SUCH AS A MICROCOMPUTER*

VIRTUAL STORAGE METHOD OF HANDLING SEVERAL PROGRAMS IN PRIMARY STORAGE: PROGRAM DIVIDED INTOPROGRAM DIVIDED INTO –FIXED LENGTH PORTIONS (PAGES) OR –VARIABLE LENGTH (SEGMENTS) CURRENT PORTIONS RESIDE IN PRIMARY STORAGECURRENT PORTIONS RESIDE IN PRIMARY STORAGE PORTIONS SWAPPED OUT WHEN DONEPORTIONS SWAPPED OUT WHEN DONE*

TIME SHARING MANY USERS SHARE LARGE CPU: TIME IN CPU DIVIDED INTO SLICES (e.g.: 2 MILLISECONDS)TIME IN CPU DIVIDED INTO SLICES (e.g.: 2 MILLISECONDS) EACH USER HAS ACCESS TO CPU DURING SLICEEACH USER HAS ACCESS TO CPU DURING SLICE SINCE CPU IS FAST, CAN DO MUCH DURING TIME SLICESINCE CPU IS FAST, CAN DO MUCH DURING TIME SLICE USER’S JOB SWAPPED OUT AT END OF SLICEUSER’S JOB SWAPPED OUT AT END OF SLICE*

MULTIPROCESSING TWO OR MORE PARALLEL PROCESSORS IN SYSTEMTWO OR MORE PARALLEL PROCESSORS IN SYSTEM PROGRAM CAN BE DIVIDED TO BE PROCESSED BY MULTIPLE CPUsPROGRAM CAN BE DIVIDED TO BE PROCESSED BY MULTIPLE CPUs CAN PROCESS LARGE PROGRAMS MORE RAPIDLYCAN PROCESS LARGE PROGRAMS MORE RAPIDLY*

TRANSLATION PROCESS SOURCE CODE PROGRAM COMPILER OBJECT CODE LINKAGE EDITOR LOAD MODULE OTHER OBJECT CODE MODULES

MICROCOMPUTER OPERATING SYSTEMS OPERATING SYSTEM FEATURES DOS For IBM (PC-DOS) and PC (MS-DOS). Program Memory: 640K Windows bit operating system; GUI; Multitasking. Networking Windows NT 32-bit; microcomputers & workstations. Not limited to Intel chips. Multitasking; Multiprocessing; Networking OS/2 32-bit. Developed for IBM PS/2. Multitasking; Networking UNIX; XENIX For powerful Microcomputers, Workstations, Minicomputers. Multitasking; Multi-user Processing; Networking. Portable to various Computer Platforms System 7 For Macintosh computers. Multitasking. Powerful Graphics; Multimedia

GENERATIONS OF PROGRAMMING LANGUAGES 1st. Since 1940s. MACHINE LANGUAGE: binary code 2nd. Since early ’50s. ASSEMBLY LANGUAGE: mnemonics for numeric code 3rd. Since mid ‘50s. HIGH-LEVEL LANGUAGES 4th. Since late ‘70s. MODERN APPLICATION PACKAGES *

HIGH-LEVEL LANGUAGES PL/1 (Programming Language 1). Powerful IBM Language for Business & SciencePL/1 (Programming Language 1). Powerful IBM Language for Business & Science PASCAL. Used to Teach Structured Programming Practices. Weak in File Handling, Input / OutputPASCAL. Used to Teach Structured Programming Practices. Weak in File Handling, Input / Output ADA. Designed for Weapon Systems. Can be used on many Platforms. Structured. Can be used for BusinessADA. Designed for Weapon Systems. Can be used on many Platforms. Structured. Can be used for Business C. Powerful PC Language for Developing Applications. Efficient Execution; Cross PlatformC. Powerful PC Language for Developing Applications. Efficient Execution; Cross Platform*

FOURTH GENERATION LANGUAGES (4GL). SOFTWARE PACKAGE: COMMERCIALLY AVAILABLE SET OF PROGRAMS... WORD PROCESSINGWORD PROCESSING SPREADSHEETSSPREADSHEETS DATA MANAGEMENTDATA MANAGEMENT PRESENTATION MANAGEMENTPRESENTATION MANAGEMENT INTEGRATED SOFTWARE PACKAGES NOW COMBINE THESE TO SIMPLIFY LEARNING AND USE *

XML and ASP XML (eXtensible Markup Language)XML (eXtensible Markup Language) –Defines data and data definitions –Allows companies to interface data communications –Replacing EDI interfacing ASP (Application Service Provider)ASP (Application Service Provider) –Provides applications / services over the Internet rather than having to purchase stand alone software. –Rent vs. Buy Software –TCO (upfront costs, longevity, maintenance)

OBJECT-ORIENTED PROGRAMMING COMBINES DATA & PROCEDURES INTO A SINGLE OBJECTCOMBINES DATA & PROCEDURES INTO A SINGLE OBJECT PROGRAM SENDS MESSAGE TO OBJECT TO PERFORM EMBEDDED PROCEDUREPROGRAM SENDS MESSAGE TO OBJECT TO PERFORM EMBEDDED PROCEDURE OBJECT’S DATA ENCAPSULATED FROM REST OF SYSTEMOBJECT’S DATA ENCAPSULATED FROM REST OF SYSTEM CREATES REUSABLE CODECREATES REUSABLE CODE REDUCES TIME AND COST OF WRITING SOFTWAREREDUCES TIME AND COST OF WRITING SOFTWARE*

Objects Abstract: What are they?Abstract: What are they? Why use themWhy use them –Debugged –Cost –Standardized Properties and MethodsProperties and Methods

OBJECT-ORIENTED PROGRAMMING VISUAL PROGRAMMING: SELECT AND ARRANGE OBJECTS RATHER THAN WRITE CODE CLASS: ALL OBJECTS OF A CLASS HAVE ALL FEATURES OF THAT CLASS INHERITANCE: SPECIFIC CLASS RECEIVES FEATURES OF A MORE GENERAL CLASS OVERRIDE: SUBCLASS MAY OVEERRIDE INHERITED METHOD (e.g.: Printout of an HOURLY worker Pay Check may differ from that of a WEEKLY worker *

JAVA Object orientatedObject orientated Similar to C++Similar to C++ Portable across platform / InternetPortable across platform / Internet Applets / ApplicationsApplets / Applications Java Virtual machine / slowJava Virtual machine / slow Why did Microsoft feel threatenedWhy did Microsoft feel threatened –Active X –Strengthens other environments than Windows

TCO (Total cost of ownership) A 1000 PC (486-P4) company is trying to decide whether to install a Windows platform with Microsoft Office or a Linux system with Oo (Open source office: word processor, database and spreadsheet). What factors must be considered in assessing the TCO?

6. INFORMATION SYSTEMS SOFTWARE