Information and Communication Technology Lecture 6 Reference: Chapter 5

Software A series of instructions to be executed by hardware.

Uses of Software To control hardware Operating Systems Device Drivers BIOS Complex functionalities Applications Web site Databases Mobile App

Programming Languages Low-level programming languages: Machine Code, Assembly High-level languages C, C++, C#, Java JavaScript, VBScript HTML, XML Low-level language is faster to execute due to ability to optimize according to the hardware design High-level language is much easier to read and program and abstract the tedious details related to the hardware.

Assembly Languages Tied specifically to the instruction set used by processor or process family. Assembler converts assembly language to machine code. Provides symbolic reference to data Used in BIOS, device driver, embedded system.

High-level Languages Compiled Languages: source code is compiled to some lower level binary executable. C, C++ Interpreted Languages: Source code is compiled into a byte code that can be executed in various operating system platforms with appropriate interpreter. Java Scripting Languages: Source code is distributed and appropriate software interpreted the code. JavaScript, VBScript Markup Languages: text annotation that describe text data or the format of the data. Text can be fed to any program that understands the annotation. HTML, XML

Compiled Languages Source code is compiled to machined code. Executable cannot be run on different O/S. Compiler checks for syntax error. Examples: C, C++ Source Code Windows Compiler Windows executable Linux Compiler Linux executable

Interpreted Languages Source code is compiled to byte code. Byte code then compiled by interpreter into machine code. Compiler checks for syntax error. Examples: Java,.NET Source Code Compiler Byte Code Windows Interpreter Windows machine code Linux Interpreter Linux machine code

Simple C program

Same program in Java

Script/Markup Languages Script is a light weight and weak- typed interpreted language No byte code; the source code or the text data delivered to end user. Examples: JavaScript, VBScript HTML, XML Internet Explorer User GUI Firefox User GUI Source Code

HTML page with JavaScript

Types of Software System Software BIOS, operating system (O/S), device drivers Application Software Word, Excel, Outlook, Open Office. Web Browser, Windows Live iTunes, Windows Media Player Enterprise software System software provides Application software an interface to control computer hardware. Application software allows computer user to perform task without worry about the details of hardware specification.

BIOS BIOS: Basic Input / Output System Loads driver, operating system Things included in BIOS – Boot order of multiple O/S and boot devices such as CD-ROM, hard drive, USB flash drive. – Device configuration – Loads O/S

Operating System Manages directories, folders, and files Manages memory Manages hardware and software Provides computer networking functions Example: Windows, DOS, Unix, Apple Macintosh, Linux, Android.

Operating Systems

Productivity Applications Allow users to quickly performs tasks and increase their productivity Word software allows a report to be done quickly. Spreadsheet allows a person to quickly analyze data such as sum and average and present numerical data in easy to read format. Outlook automatically download s and reminds a user of new s.

Communication Applications Browser allows an user to gain knowledge through World Wide Web. Instant messaging software allow friends and family stay in touch even if they are on the other side of the globe. VoIP software allows meeting to be taken place without attendees to be present in one physical location.

Multimedia Applications iTunes and MP3 that plays music and stores songs on hard drives or portable flash drives. Windows Media Player displays a group of pictures as a photo album. Adobe flash provides interactive content to web page. Useful for online game development.

Enterprise Applications Employee management software such as PeopleSoft manages employee and payroll Salesforce manages sales team and assign inventory to individual sales person. Inventory software tracks amount of an item is in stock and sends reminder for low inventory count items. Customer management software stores contact and account information of customer.

Software Development Process Waterfall Iterative / Spiral Agile Open source

Water fall model The waterfall model consists of several critical phases, each of which must be fully completed before the next stage can commence During the definition phase, the software company interacts with the customer to clarify needs and constraints Before actually writing code, the software development team must thoroughly understand the customer’s requirements and limitations

Water fall model

Customer Constraints Examples of constraints on the customer’s side may include: – Economic limitations – Time constraints for software implementation – Maintenance costs for managing the product Information Technology in Theory25

Customer Requirements Requirements may include: – Detailed business-specific functions that the software will support – Information about who will use the product – Security criteria – Specifications for interacting with existing data stores Information Technology in Theory26

Software Design Once requirements are clearly defined, a design team works to create the software’s design architecture – Accounting for tools that would be most useful to ensure compatibility with the customer’s systems – Minimizing problems that the development teams are likely to face Software programmers and engineers then start to write programs using the selected approach Information Technology in Theory27

Software Testing The software is tested to remove and fix any errors, or bugs Testing may be implemented in two stages called alpha testing and beta testing Alpha testing is normally conducted by the software development team Then the software undergoes beta testing, and a beta version of the complete software is released to the customer Customers report bugs to the developer Information Technology in Theory28

More on Software Development Models!

Iterative After initial planning phase, the development process is iterated through several stages including planning, requirement analysis, deployment, testing, evaluation.

Spiral

Agile Release frequent prototype versions allowing end users to modify requirements and communicates with the development teams through out the development process.

Open Source Software Source code is openly available to the public Anyone can view, copy, or change the software without having to pay licensing fees or royalties The development of open source code is usually collaborative, with multiple parties and interests producing the code and improving it for mutual benefit. Information Technology in Theory33

Open Source Software Open Office: can be downloaded for free from this link: Apache HTTP Server Linux Mozilla Firefox MySQL

Summary Discussed High-level and Low-level languages Discussed various Application Software. Discussed various methods of software development.

Points to Ponder! Question – Real life Examples of different types of software and their purpose. – You have to prepare one example from industry Name Which type of software is it? Its purpose!