Software BasicsSoftware Basics

The Ghost in the Machine

4

2001 Prentice Hall 4.2

Chapter Outline

• 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

“All experience shows technological changes profoundly transform political and social relationships.”

John von Neumann

2001 Prentice Hall 4.3

Processing with Programs

Software programs are:

– stored in memory

– a set of instructions that tell a computer what to do

– designed to solve problems

2001 Prentice Hall 4.4

Food for Thought

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

2001 Prentice Hall 4.5

A Fast, Stupid Machine

Computers:

– Have limited capabilities

– Can only do basic mathematics and logical comparisons

– Must be instructed with programs what to do

2001 Prentice Hall 4.6

The Language of Computers

• Programmers begin with an algorithm, which 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

2001 Prentice Hall 4.7

Programming Languages

Bridge the gap

Human language

Numeric code

COBOL, BASIC, and C++

2001 Prentice Hall 4.8

Software Applications:Tools for Users

Software applications include:

– Consumer software

– Integrated software

– Vertical-market and custom software

2001 Prentice Hall 4.9

Consumer Applications

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

– Documentation

– Upgrade options

– Compatibility

– Warranty

– Extent of ownership/license

2001 Prentice Hall 4.10

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

2001 Prentice Hall 4.11

Upgrades

• Newer releases often have additional features and fewer bugs

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

2001 Prentice Hall 4.12

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

2001 Prentice Hall 4.13

Warranty

• Software manufacturers limit their liability for software problems byselling their software “as is”

• Error-free software does not exist

Buyer Beware!

2001 Prentice Hall 4.14

Ownership/Licensing

• Three categories:

– Purchased software grants you a license to use the software as the software company tells you

– Shareware software is free for the trying, but a nominal fee is to be paid to the programmer if you continue to use it

– Public domain software is legally free and cannot be owned or licensed

2001 Prentice Hall 4.15

Integrated Applications and Suites:

Software Bundles

• Multipurpose software includes most of these modules:

– Word processing

– Database

– Spreadsheet

– Graphics

– Telecommunications

2001 Prentice Hall 4.16

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

2001 Prentice Hall 4.17

Vertical-Market andCustom Software

• Job-specific software:

- Medical billings

- Library cataloging

- Restaurant management

- Single-client software needs

2001 Prentice Hall 4.18

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

2001 Prentice Hall 4.19

Utility Programs

– repairing damaged files

– making it easy for users to copy files from one storage device to another

– translating files so differentsoftware can read them

– guarding against viruses

Utility software controls tasks such as:

2001 Prentice Hall 4.20

Where the Operating System Lives

• 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

• Some computers store their operating system in ROM

2001 Prentice Hall 4.21

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)

2001 Prentice Hall 4.22

A Character-Based Interface: MS-DOS

• This is a disk operating system in which the user interacts using characters

– letters

– numbers

– symbols

2001 Prentice Hall 4.23

A Character-Based User 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)

2001 Prentice Hall 4.24

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, theMacintosh™ computerwas designed with thisinterface in mind

2001 Prentice Hall 4.25

Graphical User Interfaces: Windows

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

• Several versions of Windows exist for business and home users

2001 Prentice Hall 4.26

Why WIMP Won

Windows, Icons, Menus, and Pointing devices• They’re intuitive

• They’re consistent

• They’re forgiving

• They’re protective

• They’re flexible

2001 Prentice Hall 4.27

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

2001 Prentice Hall 4.28

• UNIX remains a dominant Internet operating system for Internet servers.

Multiple User Operating Systems: UNIX and Linux

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

2001 Prentice Hall 4.29

Hardware & Software Platforms

• Windows 9x(ME)

• Windows 2000

• Windows CE

• Palm OS

• IBM’s OS/2

• Mac OS/9

• Mac OS/X

• UNIX & Linux

• BeOS

2001 Prentice Hall 4.30

Rules of ThumbConsumer Concepts

Before you buy:

– Join a user group ortalk with other computerand software owners

– Allow for “extras”

– Determine what you can afford

2001 Prentice Hall 4.31

Rules of Thumb: Consumer Concepts

• What kind of tasks you will be doing

• If your computer can be customized to fit your needs (such as video editing)

• How much computer power you need

Consider:

• If the processor canhandle your demands

• If you will be able to upgrade

2001 Prentice Hall 4.32

Rules of Thumb: Consumer Concepts

• If you need a high-speed modem or network connection

• Whether portability or permanent connection of peripherals is important

• Which kind of user interface will help you do your work easier

Consider:

• If you should have the same machine as those you work with

• If you are buying from a reputable company

• What kind of support is available

2001 Prentice Hall 4.33

Tomorrow’s User Interfaces

– Make individual applications obsolete

– Support natural languages(talk to the machine and it talks back)

– Include artificial intelligenceand agents that fit our needs

– Be based on virtual reality(data in three-dimensional physical space)

Future interfaces will probably: