Chapter 4

Software Basics: The Ghost in the Machine 

Linus Torvalds and the Software Nobody Owns

Linus Torvalds

Best known as the Linux creator

The Linux operating system is the best-known example of open source software.

Today Linux powers Web servers, film and animation workstations, scientific supercomputers, and a handful of handhelds. 

The three major categories of software:

1. Compilers and other translator programs: enable programmers to create other software

2. Software applications: serve as productivity tools to help computer users solve problems

3. System software: coordinates hardware operations and does behind-the-scenes work the computer user seldom sees

OS vs. Application software

Food for Thought

The hardware in a computer system is equipped to produce whatever output a user requests.

A Fast, Stupid Machine

>Programmers begin with an algorithm: a set of step-by-step instructions written in a natural language, e.g., English.

>The steps are often ambiguous, error-prone generalities.

>The steps are translated into the vocabulary of a programming language.

The Language of Computers

            1.   Machine Language: numeric codes that represent data

2.    High-level language: falls between machine language and natural human language

      Compilers translate high-level language into machine language.

3.    Natural Languages: resemble languages spoken by humans

Consumer Applications

Many software companies have replaced their printed documentation with:

Tutorials

b.      Reference materials

c.       Help files

d.      On-line help

Upgrading: Users can upgrade a program to the new version by paying an upgrade fee to the software manufacturer.

Newer releases often have additional features and fewer bugs.

Compatibility

>>It 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.

Disclaimers

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

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

~ Software license

~ Volume licenses

Distribution: Software is distributed via:

~ Direct sale

~ Retail stores

~ Mail-order catalogs

~ Web sites

Not all software is copyrighted.

+ Public domain software

+ Shareware 

Integrated Applications and Suites: Software Bundles

Vertikal market and custom software

Tends to cost far more than mass-market applications

Job-specific software:

> Medical billings

> Library cataloging

> Legal reference software

> Restaurant management

> Single-client software needs

The Hardware-Software Connection

System software 

A class of software that includes the operating system and utility programs, handles these details, and hundreds of other tasks behind the scenes

Operating system functions:

a.      Supports multitasking

b.      Manages virtual memory

c.       Maintains file system

d.      Responsible for authentication and authorization

 
 

Device drivers

Small programs that enable I/O devices—keyboard, mouse, printer, and others—to communicate with the computer

Included with the operating system or bundled with peripherals

Where the Operating System Lives

a.      Some computers store their operating system in ROM.

b.      Others include only part of  it in ROM.

The remainder of the operating system is loaded into memory in a process called booting, which occurs when you turn on the computer.

Most of the time the operating system works behind the scenes.

Interacting with the operating system, like interacting with an application, can be intuitive or challenging and it depends on something called the user interface.

The interface defines the look and feel of the computing experience from a human point of view. 

Desktop Operating Systems

MS-DOS is a disk operating system in which the user interacts using characters:

a.      Letters

b.      Numbers

c.       Symbols

Graphical User Interfaces (GUI)

> Mac OS  was developed by Macintosh in 1984 using GUI.

> Microsoft Windows is now the most popular operating system.

Hardware and Software Platforms

Windows Vista                                                    Microsoft Windows CE

Windows Server 2003                        Mac OS X (10)                                                   

Windows XP                                                       Mac OS 9

Windows ME                                        Linux, Sun Solaris, and other variations

Tomorrow’s User Interfaces

Future user interfaces will be built around emerging development technologies such as:

>>> The end of applications

>>> Natural-language interfaces

>>> Agents

>>> Virtual realities 

Files can be scattered all over the system, which often makes data management difficult.

1.   One solution to this problem is to organize data files logically.

2.   Both Windows and the Mac support the notion of common system folders with self-explanatory names:

a.       My Documents (Documents)

b.      My Pictures (Pictures)

c.       My Music (Music)

File-Management Utilities

> View, rename, copy, move, and delete files and folders

> Hierarchies help with organization

> Help with locating a file

> Get size, file type, and last modification date

Managing Files from Applications

Operations: Open, Save As, Save and Close

Defragmentation

Inventing the Future Tomorrow’s Evolving Applications and Interfaces

The WIMP (windows, icons, menus, and pointing devices) interface is easier to learn and use than earlier character-based interfaces.

The SILK interface incorporates many important emerging user interface software technologies:

>> Speech and language

>> Image

>> Knowledge

Popular operating systems include Windows, Mac OS X, UNIX, and Linux.

The user interface is a critical communication component in operating systems, applications, programming languages, and utilities.

Tomorrow’s interfaces are likely to rely on three-dimensional graphics and animation to create virtual realities.

Software piracy is a major concern in the computer industry.

~ooo~