software basics

Software BasicsIntroduction to Computer Science

2007-2008

4626. Introd to Computer Science

Aims

• Describing main sw categories and their relationship

• Explaining relationship between algorithms and programs

• Discussing factors that make apps useful

• Describing the role of operative systems

• Outlining the evolution of interfaces


How the sw works?

algorithm

thinks thinks

Problem: natural language is ambiguous

thinks


How the sw works?

thinks

writes

algorithm

thinks thinks

program… but

computers can’t

understand that


How the sw works?

thinks

writesalgorithm

thinks thinks

program(source code)

executable(binary code)

generates


Example

1. Ask the user for a number

2. Multiply it by 2

3. Show the result on the screen

Algorithm


Example

#include <stdio.h>

void main(){

int num, double;

printf( “Enter a number: “ );scanf( “%d”, &num );double = num * 2;printf(“Twice %d is %d\n”, num, double );

}

Source code


Example010110011101110000001000001111010001111011111000101111100010001001001111001001101011100001111001001101011000110111001001100111100010110011100010001011011011011010111010010100011111000011001000111000100011101111000101010010100100110011111110011100111000111110111110110100011100001110000100101111010011110110010011100001101110

Binary code


Development software

Softwareclassification

Applicationsoftware

Systemsoftware

Softwareclassification


Development software

• Assisting programmers to write software

• Typical tools

Text editor

Debugger

IDE

Compiler


Application software

• Why do we use application sw?

• visual metaphors of the real world

• extend human capabilities

(pictures from tecnomarketer)



• Examples: accounting, library cataloguing or restaurant management

• limited market (high cost)

• sometimes developed for just one customer

Vertical market

Specific software for a sector


Application software• Common applications

• Used in many fields (home, office, education, administration….)

• Sold separately or in a package (suite)

Suites

Apps that “work well together”



• Set of applications sold in a block

• Easy earning

• Limited functionality (but enough)

• Cheaper

Integrated packages

Share the same environment


System software

• Manages communications between hw & sw

• Abstraction from hw details(virtual machine)

(source: FFP Basic http://iaf-bs.de)


Device drivers

• Communicates computer and I/O devices

• Extends computer (open architecture)

• Brokers to access the device

• You can get them

• included in the OS

• provided with the device (install CD)

• owned by a third company (buy it)


Operative systems

• brokers between users/programs & Hw

• isolations layer

• programs compatibility

• main tasks

• ease the use of the computer

• use the software efficiently


OS functions

• communications with peripherals (I/O)

• process management (multitasking)

• memory management (protection & virtual mem)

• resource monitoring for accounting and safety

• file system management

• network communication coordination


Utility programs

• System maintenance tools

• Executed apart from OS

• We can find them…

• incorporated into the OS (disk defrag)

• provided by others (antivirus)


Additional considerations

• instructions about how to install them

• tutorials

• reference manuals

• help files

• on line help systems

• support services, FAQ

Documentation


Additional considerationsUpgrading



• periodically, companies sell new versions

• reasons: improvements, bugs, adaptation to other SW (OS)

• versions identified by numbers(decimals for minor changes)

• right to free updates during a period

Upgrading



• constraints about computer and resources

• examples: CPU, memory, free HD space

• operative systems (Windows, MacOS, Linux)

• sometimes, version:Windows 95, 98, NT, Me, 2000, XP, Vista..

Compatibility

Hardware Software



• you don’t buy sw, you buy a license

• individual and corporative licenses

• main limitation: number of computers and right to copy (backup)

• EULA (End User License Agreement)

• license terms

• disclaimer terms (limited liability)

Licensing



• proprieraty

• shareware

• demo

• adware

Distribution

• freeware

• open source / free software

• semi free

• public domain


User interface• character console:

command line (MSDOS)

• graphical user interface (GUI)

• visual concepts

• controls individual points on the screen

• Apple MacOS (1984)

• metaphors. desktop, folders, documents…

• active elements:

• icons

• buttons

• windows

• scrolling bars

http://www.youtube.com/watch?v=OYecfV3ubP8

http://www.youtube.com/watch?v=OYecfV3ubP8

http://technewsdaily.blogspot.com/2007/11/desktop-evolution-windows-and-mac-os.html

http://technewsdaily.blogspot.com/2007/11/desktop-evolution-windows-and-mac-os.html


MS-DOS


Windows 3.11


Windows 95


Windows XP


Windows Vista


Linux


Mac OS X (Leopard)


File system management

• specific folders for user’s documents

• search tools by name or content(Google Desktop)

• Specific tools for special files (iTunes)


Multi-user OSUNIX

• preferred OS for mainframes & workstations

• versions: Solaris (Sun), HP-UX (HP), Aix (IBM) IRIX (Silicon Graphics)

Linux

• Unix versions for PCs

• Distributions: Ubuntu, Suse, RedHat…

software basics

Technology

computer science pictures

system software

application sw

software efciently4626

software basics introduction

customer specic software

main sw categories

hw sw abstraction