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Chapter 4

Software Basics:

The Ghost in the Machine

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Topics

Processing with Programs

Software Applications: Tools for Users

System Software: The Hardware-Software Connection

The User Interface: The Human-Machine Connection

Tomorrow’s User Interfaces

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Processing with Programs

Software programs are:

Stored in memory

Instructions that tell the computer what to do

Designed to solve problems

Leonardo da Vinci called music ”the shaping of the invisible,“ and his phrase is even more apt as a description of software.

—Alan Kay, developer of the concept of the personal computer

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Food for Thought

1. Combine 2 slightly beaten eggs with 1 tsp vanilla extract, ½ tsp cinnamon, 1 cup milk

2. Dip 6 slices of bread in mixture

3. Fry in small amount of butter until golden brown

4. Serve bread with maple syrup, sugar, or tart jelly

Suzanne’s French Toast Fantastique:

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A Fast, Stupid Machine

Computers:

Perform arithmetic and comparisons capabilities

Follow precise instructions to perform an operation

Execute instructions quickly and accurately

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A Fast, Stupid Machine

Programmers begin with an algorithm

An algorithm is: A set of step-by-step instructions (written in a natural

language, e.g., English)

Algorithms are ambiguous, error-prone generalities

Algorithms are translated into the vocabulary of a programming language

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The Language of Computers

Machine Language numeric codes to represent data

High-level language fall between machine language and natural human language

Compilers translates high-level language into

Natural Languages include the languages spoken by humans

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Software Applications:Tools for Users

Software applications include:

Consumer Applications

Integrated Software

Vertical-market

Custom Software

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Consumer Applications

• Consumer software differs from other types (music CDs, videos, etc.) based on:

Documentation

Upgrade options

Compatibility

Warranty

Extent of ownership/license

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Documentation

Documentation includes:

Printed tutorial and reference manuals that explain how to use the software

On-line manuals and help screens which offer immediate help to the user

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Upgrades allow you to pay a fee to get the latest software version

Newer releases often have additional features and fewer bugs

Upgrades

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Compatibility

Compatibility allows software to function properly with the hardware, operating system, and peripherals

Programs written for one type of computer system may not work on another

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Disclaimers

Software manufacturers limit their liability for software problems by selling software “as is”

Given the difficulty of this task, most programs work amazingly well—but not perfectly

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Licensing

Licensing agreements limit your right to: Make copies of software disks install software on hard drives transfer information to other users

Commercial software is copyrighted so it can’t be legally duplicated for distribution to others.

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Distribution

Software is distributed through direct sales forces to corporations and other institutions.

Software is sold to consumers through: retail stores mail-order catalogs Web sites.

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Integrated Applications and Suites: Software Bundles

Multipurpose software includes most of these modules: Word processing Database Spreadsheet Graphics Telecommunications

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Integrated Software: Advantages

Costs less than buying the applications individually

Data is easily transferred between modules

Commands used in each module are usually the same

Usually there is a seamless integration of the modules

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Vertical-Market andCustom Software

Job-specific software: Medical billings Library cataloging

Restaurant management Single-client software needs

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System Software: The Hardware-Software Connection

System software is a class of software that includes: The operating system Utility programs

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What the Operating System Does

The operating system controls: Communication with peripherals Coordination of concurrent processing Memory management Monitoring of resources and security Management of programs and data Coordinating network communications

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Utility Programs

Upgrades allow you to pay a fee to get the latest software version

translating files so different software can read them

guarding against viruses

repairing damaged files copying files from one

storage device to another

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Where the Operating System Lives

Some computers store their operating system in ROM

Others include only part of it in ROM The remaining system is

loaded into memory (booting)

Most of the time it works behind the scenes

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The User Interface: The Human-Machine Connection

The user interface is what the user sees on the screen

Two major user interface types:

Character-based interface

Graphical user interface (GUI)

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A Character-Based Interface: MS-DOS

This is a disk operating system in which the user interacts using characters letters numbers symbols

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A Character-Based Interface: MS-DOS

MS-DOS™ is the most widely used general-purpose operating system

Features include: Command-line interface (commands are typed) Menu-driven interface (commands are chosen from

on-screen lists)

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Graphical User Interfaces: Macintosh

This is a disk operating system in which the user interacts with the computer by using a pointing device (e.g. a mouse)

As early as 1984, the Macintosh™ computerwas designed with this interface in mind

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Graphical User Interfaces: Windows

Windows 95 and 98 are similar in many ways to the Mac OS

Several versions of Windows exist for business and home users

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Why WIMP Won

Windows, Icons, Menus, and Pointing devices

• They’re intuitive

• They’re consistent

• They’re forgiving

• They’re protective

• They’re flexible

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Multiple User Operating Systems: UNIX and Linux

UNIX was developed at Bell Labs before personal computers were available

Linux was created by Linus Torvalds and continues to be a work-in-progress Linux is free for anyone to use or improve

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UNIX remains a dominant Internet operating system for Internet servers.

These systems allow a timesharing computer to communicate with several other computers or terminals at once.

Multiple User Operating Systems: UNIX and Linux

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Hardware & Software Platforms

Windows XP

Windows ME

Windows 2000

Windows CE

Palm OS

IBM’s OS/2

Mac OS/9

Mac OS/X

Linux & UNIX

BeOS

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Tomorrow’s User Interfaces

Make individual applications obsolete Include more network applications Support natural language interfaces such

as talking to the machine Include artificial intelligence and agents Be based on virtual reality

Future interfaces will probably:

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