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Chapter 5Information

Systemsin Business

Software

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Software: Instructions to the Computer

A computer program is a series of instructions to a computer to execute any and all processes.

Computers only “understand” instructions consisting of electrical signals alternating between two states.

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Programming Languages

Programming languages

Abbreviated forms of instructions that translate into machine language

New programming languages make programming easier for people who are not necessarily hardware experts

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Machine Languages (ML)

Only languages computers can directly interpret to carry out instructions

ML coding: time-consuming and error-prone

ML programmers: concerned with hardware details

Every computer or family of computers has its own ML; each is machine-dependent.

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More English-like; codes shorter than machine languages

Assembler translates into machine language

Advantages of machine or assembly languagesProgrammer in control of hardwarePrograms written in low-level languages

run more efficiently.

Assembly Languages

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Procedural Languages

Third-generation (procedural) languages are more English-like than assembly languages.

Relatively easy to learn, write, and debug.

FORTRAN, COBOL, BASIC

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4GLs are more English-like than procedural languages.

Easy to learn and use; shorter application development time.

PowerBuilder, FOCUS, NOMAD, and RAMIS

Fourth Generation Languages (4GL)

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Levels of programming Language:

9-179-17

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Languages that let programmers create field windows, scroll-down menus, click buttons, etc., by choosing from a palette

Appropriate code written automatically

Accelerates work

Microsoft’s Visual Basic

Visual Programming

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Emphasis on the objects involved in the task, not on the procedure

An object encapsulates a data set with the code that is used to operate on it

Standardized programming modules can be reused

Object-Oriented Programming (OOP)

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Advantages of Object-Oriented Programming

over Procedural Languages

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Advantages and disadvantages

of higher-level programming languages

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Application: a program developed to address a specific business need; software for development of such programs.

System: programs designed to carry out general routine operations, such as loading, copying, or deleting a file.

Application Software vs.

System Software

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Application Software

Custom-Designed Applications Advantages:

Meeting the organization’s needs exactly

In-house developers are sensitive to the organizational culture

Disadvantages:High costProduction schedule subject to long

delays Incompatible with other

organizations’ systems

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Advantages and disadvantages of tailored applications

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Advantages:Low costHigh qualityVendor support Immediate availability

Often tested at user sites (alpha sites and beta sites) before the final version is released

Packaged Software

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Advantages and disadvantages

of packaged software

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System SoftwareManages computer resources and performs routine tasks not specific to any application Copying and pasting sections and files Printing documents Allocating memory

Developed to partner with application software

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Most important system software

Developed for a certain microprocessor or microprocessors

Plays the role of “traffic cop” or the “boss” of computer resources

Operating Systems (O/S)

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The operating system mediates between applications and the computer, and controls peripheral devices.

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Systems Management

User Interface

Memory Allocation

Multitasking, Multiprogramming, and Multiprocessing

Times and Statistics

Increasing Services from O/Ss

Operating System Functions

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MICROCOMPUTER OPERATING SYSTEMSMICROCOMPUTER OPERATING SYSTEMS

32-bit operating system; GUI; Multitasking. 32-bit operating system; GUI; Multitasking. NetworkingNetworking

32-bit operating system not limited to Intel chips. 32-bit operating system not limited to Intel chips. Multitasking; Multiprocessing; NetworkingMultitasking; Multiprocessing; Networking

32-bit. Developed for IBM PS/2. Multitasking; 32-bit. Developed for IBM PS/2. Multitasking; NetworkingNetworking

Paired-down for handheld computers, wireless Paired-down for handheld computers, wireless communication devicescommunication devices

Windows 98 & Windows 98 & 9595

Windows NT Windows NT Me, Me,

2000&XP2000&XP

Windows CEWindows CE

OS/2OS/2

OPERATING SYSTEMOPERATING SYSTEM FEATURESFEATURES

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OPERATING SYSTEMOPERATING SYSTEM

MICROCOMPUTER OPERATING SYSTEMSMICROCOMPUTER OPERATING SYSTEMS

Mac OSMac OS For Macintosh computers. Multitasking. For Macintosh computers. Multitasking. Powerful Graphics; MultimediaPowerful Graphics; Multimedia

UnixUnix For powerful Microcomputers, Workstations, For powerful Microcomputers, Workstations, Minicomputers. Multitasking; Multi-user Minicomputers. Multitasking; Multi-user Processing; Networking. Portable to various Processing; Networking. Portable to various Computer PlatformsComputer Platforms

DOSDOS For IBM (PC-DOS) and PC (MS-DOS). For IBM (PC-DOS) and PC (MS-DOS). Program Memory: 640KProgram Memory: 640K

LinuxLinux Free, reliable alternative to Unix, Windows. Free, reliable alternative to Unix, Windows. Runs on many PlatformsRuns on many Platforms

FEATURESFEATURES

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Popular Operating System

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Compiler Scans source code and translates into

object code Generates error message and does not

compile when an error is found Allows users to save programs in object

code

Interpreter Checks one statement at a time Changes error-free statements into ML Generates an error message for errors

Compilers and Interpreters

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Controls and supports data communication activities in a network

Setting up rules that govern transmission and reception of data

Connecting and disconnecting communication links

Assigning priorities among terminals in a network

Detecting and correcting transmission errors

Data Communication Programs

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Proprietary O/S: limited to using applications compatible with it

Open O/S: compatible with virtually all applications.

Completely open O/S does not exist

Some O/Ss (e.g., Unix) are said to be nonproprietary, but it is still impossible to run many applications on different versions of such O/Ss.

Proprietary vs. Open Source

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Sample results of software evaluation

(5 is the highest score.)