Module Four: Computer Software (Notes)
The physical components of a computer together are referred to as hardware.
When user interact with computer the first perception comes to mind is of hardware part of computer. BUT computer hardware must be programmed to produce useful information. The Computer programs which are usually planned and step by step instruction are what we term as software.
The software components of a computer system are the intangible parts of the computer and are stored on hardware such as hard disks or tape or DVD.
Formal Definition of Software
Software is an organized list of instructions that, when executed, causes the computer to behave in a predetermined manner.
Software is often divided into two categories:
a) Systems software
Programs that manage and support the resources (primary memory, CPU, storage devices, output devices) and operations of a computer system as it performs various information processing tasks.
Refers to the operating system and all utility programs that manage computer resources. Systems software includes compilers, loaders, linkers, and debuggers. Systems software consists of low level programs that interact with the computer at a very basic level.
b) Application software
A program or group of programs designed for end users. Applications software comprises programs designed for an end user, such as word processors, database systems, and spreadsheet programs.
What is a system software?
It is a set of programs that allows the computer to manage its own resources and run the hardware.
Lets the CPU communicates with the keyboard, the screen, printer and disk drive.
System software does not solve specific problem and it is supplied by the computer
Components of System Software
System software can be grouped as:
i. Operating system - programs that manages or coordinates computer resources, provide interface between user and computer and run applications
ii. Utilities (service programs) - perform specific tasks relating to managing computer resources.
iii. Language translators convert the programming instruction written by programmers into a language that computers understands and processes. Examples are compilers and interpreters
iv. Device drivers - specialized program designed to allow particular input or output hardware to communicate with the rest of computer system. Example is printer and network drivers
Operating system
What is an operating system?
An Operating System (OS) is a collection of system programs that together control the operation of a computer system and it acts as an intermediary between a user of a computer and the computer hardware
An example of Operating Systems includes DOS, Window95, Windows 98, Windows Vista, Linux, Unix, OS/2, Macintosh etc.
Operating system is a program that acts as intermediary between a user of a computer and the computer hardware. The purpose of operating system is to provide an environment in which a user can execute programs.
Operating system is automatically loaded into main memory as soon as you turn on or “boot” the computer
The term booting refers to the process of loading an operating system into computer’s main memory from the secondary storage
The operating system is a complex collection of many programs concerned with keeping the hardware and software components of a computer system coordinated and functioning. It is like a shop keeper who keeps a shop in order by attending to customers, handling supplier deliveries, stocking the shelves, doing the bookkeeping, and so on.
Operating system allows to concentrate on your own tasks or applications rather than on the complexities of managing the computer
Sometimes the operating system on a computer becomes corrupted (perhaps because of a computer virus) and must be tediously or dully reinstalled. Until it is up and running again, other programs will not be available.
Basic functions of operating system
User Interface - The user interface is the part of the operating system that allows the end user to communicate with the operating system so they can load programs, access files, and accomplish other tasks. More details in the next slides
Computer Resources Management
Generally it does Allocation and de - allocation of computer resources to different users or programs.
Also It Manages these resources in the face of many, potentially conflicting requests if there are many users or programs
Computer resources include CPU time, Memory space, file storage space, input and output devices, Secondary Storage Devices, Telecommunications processors.
Examples
1. Memory Space Management
– Keep track of where data and programs are stored.
- Load the user programs in the memory
- Unload user programs from main memory
2. Secondary Storage Devices Management
- Allocates the use of peripheral devices
- Checks equipment and displays error message
3. Task Management
- Allocate CPU time to tasks and interrupt tasks being executed to substitute other tasks.
- Manage the accomplishment of the computing tasks of end users.
- May involve a multitasking capability where tasks of several programs can process at the same time.
4. File Management
- Control the creation, deletion, and access of files of data and programs.
- Keep track of the physical location of files on magnetic disks and other secondary storage devices.
- Manages files stored on Hard disk and other secondary devices
- Provides a way for application software to communicate with hardware by using commands
Operating System Interfaces
The Operating System provides each user with an interface that accepts, interprets and executes user commands or programs and is known as Operating system Interfaces
Two categories of Operating System Interface
- simple text mode line by line entry or command driven
- Graphical User Interface (GUI)
a) Simple text mode or command driven - commands are typed on a keyboard by using keywords and displayed on a screen or printing terminal, with the enter (or return) key signaling the completion of command.
These types of interface are more powerful, complex and difficult to learn. Commands must be remembered or looked up in a manual. This means that users of command-line programs must memorize a great deal of specific information (with little importance outside the program), or keep consulting documentation. If one forgets the exact syntax of the command for what they need to do, they will spend time looking for it in documentation. Examples are MSDOS and UNIX
b) Graphical user interface (GUI)
A graphical user interface (or GUI, often pronounced "gooey"), is a particular case of Operating System interface for interacting with a computer which employs graphical images and widgets (button, check box, list box, radio button, menu, Window, Textbox, etc.) in addition to text to represent the information and actions available to the user. Examples of GUI OS - X-Windows, Novell Operating System Linux, OS/2 and Macintosh
Usually the actions are performed through direct manipulation of the graphical elements. The mouse is moved to place the mouse pointer on images (icons) on the screen that represent programs, files, and system functions. Clicking a button on the mouse can invoke a program, select a file or directory, or pull down men containing commands.
Graphical user interfaces are simple and easy to learn
Types of Operating Systems
a) General Purpose Operating System
b) Dedicated Operating System
c) Single - user Operating System
d) Multi - user Operating System
e) Multi - tasking Operating System
a) General - purpose Operating Systems - provides the ability to run a number of different programs, such as games, word processing, business applications and program development tools. One example is X- Windows
b) Dedicated Operating Systems
A computer that is dedicated to running a program that controls another device is known as an embedded system. An embedded system is usually embedded inside the device it controls. Usually they run just one program that is permanently kept in a special kind of main memory called ROM (for Read Only Memory). More processor chips are sold per year for embedded systems than for all other purposes.
An Operating System designed to operate and control embedded systems is often called a dedicated Operating System.
It performs a specific purpose, such as controlling the environment in a building, controlling a petrol pump, or opening and closing an automatic door.
Dedicated Operating Systems cannot be used to run other types of programs such as games or business software
c) Single - user Operating System
A single - user Operating System provides access to the computer system by a single user at a time. If another user needs access to the computer system, they must wait till the current user finishes what they are doing and leaves.
Operating Systems such as Windows 95, Windows NT Workstation and Windows 2000 professional ,MS -DOS ( Microsoft Disk Operating System are examples of single user Operating Systems.
d) Multi - user Operating System
A multi - user Operating System lets more than one user access the computer system at one time. Access to the computer system is normally provided via a network, so that users access the computer remotely using a terminal or other computer. Today, these terminals are generally personal computers and use a network to send and receive information to the multi-user computer system.
Examples of multi - user Operating Systems are UNIX, Linux (a UNIX clone) and mainframes such as the IBM AS400.
The Operating System for a large multi-user computer system with many terminals is much more complex than a single-user Operating System. It must manage and run all user requests, ensuring they do not interfere with each other. Devices that are serial in nature (devices which can only be used by one user at a time, like printers and disks) must be shared amongst all those requesting them (so that all the output documents are not jumbled up).
The advantage of having a multi-user Operating System is that normally the hardware is very expensive, and it lets a number of users share this expensive resource. This means the cost is divided amongst the users. It also makes better use of the resources. Since the resources are shared, they are more likely to be in use than sitting idle being unproductive.
One problem with multi-user computer systems is that as more users access it, the performance becomes slower and slower. Another disadvantage is the cost of hardware, as a multi-user Operating System requires a lot of disk space and memory. In addition, the actual software for multi-user Operating Systems tend to cost more than single-user Operating Systems.
e) Multi - tasking Operating System
A multi - tasking Operating System provides the ability to run more than one program at once. For example, a user could be running a word processing package, printing a document, copying files to the floppy disk and backing up selected files to a tape unit. Each of these tasks the user is doing appears to be running at the same time.
A multi - tasking Operating System has the advantage of letting the user run more than one task at once, so this leads to increased productivity. The disadvantage is that more programs that are run by the user, the more memory that is required.
Operating system platforms
There are several types of operating systems platforms such as :
1. WINDOWS
2. DOS
3. LINUX
4. UNIX
5. OS/2
6. Macintosh OS
1. X - WINDOWS (95, 98, NT. 2000. ME, XP, Vista)
- It was developed by Microsoft company in 1985
- It made the computer to be more developed and user friendly by providing graphical user interface
- Since its introduction, it has evolved through several version
- It is mostly used for microcomputers and medium size computers
2. DOS (Disk Operating System)
- Was developed by Microsoft Company.
- Was introduced on the original IBM PC in 1982
- It was called by IBM as PC-DOS, but Microsoft marketed it as MS - DOS
- It is a simple text (command driven) interface operating system
- It is still included in all Windows Operating system versions
3. LINUX
- It is based on version of Unix
- Was developed in 1991
- It is under GPL-General Public License designed for microcomputers
- Linux is established on the Web, but it shares several features with Unix, such as multi user and multi tasking capabilities
- It is a popular OS for email, web server and local area networks
4. UTILITY PROGRAMS
- Utilities are specialized programs designed to make computing easier.
- They are used to support, enhance or expand existing programs in a computer system. The most essential are troubleshooting, antivirus, backup, file compression and uninstall programs
Examples of Utility programs are:
a) Backup - used to make a duplicate copy of information on the hard disk
b) Data recovery-used to store data that has been physically damaged or corrupted
c) Virus protection- protect your files and data from virus attack that may destroy your data.
d) Data compression for compressing data to small size
e) Uninstall programs allows you to safely and completely remove unneeded programs and related files from your hard disk.
f) Troubleshooting programs that recognize and correct problems before they become serious, example Disk Cleanup utility and Disk Defragmenter in Windows
Introduction to application software
A set of computer programs developed on the computer for specific tasks of end user such as increasing productivity of clerical tasks.
Examples are word processing, spreadsheet and database software.
Figuratively speaking, applications software sits on top of systems software because it is unable to run without the operating system and system utilities. Applications software includes programs that do real work for users.
The hardware: The CPU, the memory, input or output devices - provides basic computing resources.
The application programs- such as compilers, database systems, games and business application software define the ways in which these resources are used to solve the basic computing problems for users.
There may be many different users (people, machines, other computers) trying to solve different business or organization problems.
Types of Application Software
Application software can be divided into two categories
1. Custom or application specific programs
2. General purpose programs
1. Application specific Programs:
Application - specific programs are programs that support specific functions of end users in business and other fields. They are also known as custom software. Custom software cannot be used or sold to another user for different purposes from the intended one.
Business application - specific packages in business support managerial, professional, and business uses such as :
Transaction processing such as in banks, insurance, hospital, schools, shops, etc.
> Decision support
> Accounting
> Sales management
> Investment analysis
> Electronic commerce
Other application - specific programs support education and entertainment packages to help end users with:
> Personal finance and home management
> Entertainment products
> Educational products.
2. General Purpose Programs:
General purpose programs are programs that perform common information processing jobs for end users such as clerical or secretarial officers, administrators and secretaries. Examples include:
> Word processing programs
> Spreadsheets programs
> Database management programs
> Integrated packages
> Graphics programs
> Web browsers
> Electronic mail
Word Processing Software - Software that let user to create, edit, format, store, and print text. Word processing packages computerize the creation, editing, revision, and printing of documents by electronically processing text data.
Electronic Spreadsheet Software - Electronic spreadsheet packages are programs that are used for business analysis, planning, and modeling. They provide electronic replacement for more traditional tools such as paper worksheets, pencils, and calculators. They generate an electronic spreadsheet, which is a worksheet of rows and columns which can be stored on your PC, a network server, or converted to HTML format and stored as a web page or web sheet on the World Wide Web. Data and formulas are entered into the worksheet via the keyboard. The computer performs the calculations based on the formulas entered. Most packages also have graphic capabilities
Database Management Software - Software that can store data, update it, manipulate it and create report in a variety of forms. Database Management packages allow you to set up and manage databases on your PC, network server, or the World Wide Web. Popular database management software includes Microsoft access, Microsoft SQL server, Mysql, Oracle, and DB2.
Web Browsers - A Web browser is a software tool for displaying Web pages and for accessing the Web and other Internets resource. Web browser software features a point and click graphical user interface that can be employed throughout the Internet to access and display information stored on computers at other internet sites that can be text, graphic, audio or video information.
Web Browsers are used to:
> Surf the web
> Launch information searches
> Multimedia file transfer
> Discussion groups and workgroup collaboration
Many other Internet, intranet, and extranet applications.
Electronic Mail - Electronic mail (e-mail) is used for the computer to computer exchange of messages over a network and is an important tool for communication and collaborative work.
Software Suites and Integrated Packages
Software suites are a combination of the mode widely used productivity packages that come bundled together. They include suites such as Microsoft Office, Lotus SmartSuite, and Corel Office Pro.
Integrated software packages combine the functions of the most important PC software packages, such as word processing, spreadsheets, presentation graphics, and data management that come bundled together into one software.
Integrated packages combine some of the functions of several programs into one software package.
This integration provides a more general - purpose software tool and eliminates redundant data entry and data maintenance
Advantages of software suites
Suites integrate software packages for web browsing, word processing, spreadsheets, presentation graphics, database management, personal information management, and more.
Suites cost a lot less than the total cost of buying their individual packages separately.
All programs use a similar graphical user interface which gives them the same look and feel, and make them easier to learn and use.
Suites also share common tools, such as spell checkers and help wizards to increase their efficiency.
Programs are designed to work together seamlessly and import each others files or transfer of data between applications.
Disadvantages of software suites:
Suites take up a lot of disk space and may require significant amounts of memory. Critics argue that many software suite features are never used by most end users.
Suites may compromise on the speed, power, and flexibility of some of their functions to achieve integration
Advantages of integrated packages
- They require a lot less disk space
- Cost less than a hundred dollars
Disadvantage of integrated packages
- They cannot do as much as individual packages and software suites do.
Software Issues and Trends
Software Bugs - A software bug is a defect in a computer program that keeps it from performing in the manner intended. Some software bugs are obvious and cause the program to terminate unexpectedly.
Copyrights and Licenses - Most software products are protected by law using copyright or licensing provisions. These provisions can take a number of forms. In some cases, you are given unlimited use of software on one or two computers. In other cases, how much you pay is based on how much you use the software
Software Upgrades - Software companies periodically revise their programs and sell new versions. In some cases, the revised software offers new and valuable enhancements. In other cases, the software uses complex program code that offers little in terms of additional capabilities. When software companies stop supporting older software versions or releases, some customers feel forced to upgrade to the newer software. Deciding whether to purchase the newest software can be an issue for corporations or individuals
Global Software Support - One challenge that global companies face is ensuring adequate support for their software customers in all locations through software vendors. Slower technology growth markets, such as Eastern Europe, Latin America and Africa, might not have any official vendor presence. Instead, large vendors such as Sybase, IBM, and Hewlett Packard typically contract with local providers to support their software.
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