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Unit 3: Software Systems

• 3.1 Software Basics• 3.2 Application Software • 3.3 Operating Systems and Applications• 3.4 DOS Commands

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Unit 3.1: Software Basics

Software – Computer programs and the data used by the program. It is consists of computer program, support modules, and data modules that work together to provide a computer with the instructions and data necessary for carrying out a specific type of task.

Computer Program – is a set of self-contained instructions that tells a computer how to solve a problem or carry-out a task. It can be started or “run” by a computer user. It contains files such as main executable file, which is a program that you run to start the software.

Support Module – provides an auxiliary set of instructions that can be used in conjunction with the main software program. It is not designed to be run by a computer user. These modules are “called” by the computer program.

Data Module – contains data that is necessary for a task, but not supplied by the user.

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Software Basics

Computer Programmers – write the instructions for the computer programs and support modules that become the components of a computer software programs.

Software Publishers – companies that specialize in packaging, marketing, and selling commercial software.

Computer Language – provides the tools that a programmer uses to create software. These languages help the programmer produce a lengthy list of instructions, called, source code, that defines the software environment in every detail.

High-Level Language – have similarities to human languages and produce programs that are fairly easy to test and modify. Examples are C++, Visual Basic, Java, and Cobol

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Software Basics

Machine Language – the only language the microprocessor can understand. The instruction set that is hard-wired within the microprocessor’s circuits.

The process of translating high-level languages into machine language can be accomplished by two special types of programs:

• Compiler – translates all of the instructions in a program as a single batch, and the resulting machine language instructions, called object code, are placed in a new file.• Interpreter – converts one instruction at a time while the program is running. This method of converting high-level instructions into machine language is more common with Wed-based programs called scripts. An interpreter reads the first instruction in a script, converts it into machine language, and then sends it to the microprocessor. To run a script, your computer must have the corresponding interpreter program.

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Four Generations of Computer Software

• first generation: machine language• second generation: assembly language • third generation: high-level programming languages, such as C, C++, and Java. • fourth generation: programming languages closer to human languages than typical high-level programming languages. Main categories are query languages and report generators.

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Software Basics

Software Categories:

• Application Software

It is the software that provides the computer with instructions for each of these uses. The primary purpose of application software is to help people carry out tasks using a computer.

• System Software

The primary purpose of system software, which is the computer’s operating system, device drivers, and utilities, is to help the computer carry out basic operating function.

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Software Basics

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Licensed Software

A software license or “license agreement” is a legal contract that defines the ways in which you may use a computer program.

Installation Agreement – displayed on the screen when you first install the software. Software licenses are often lengthy and written in ‘legalese,” but your legal right to use the software continues only as long as you abide the by the terms of the software license.

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Licensed Software

Types of Software License: • Shrink–Wrap License• Single-User License• Multiple-User License• Concurrent-Use License• Site License• Shareware• Public Domain Software• Freeware• Open Source Software

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Licensed Software

• Shrink-Wrap License

When a software has a shrink-wrap license, you agree to the terms of the software license by opening the package. If you do not agree with the terms, you should return the software in its unopened package.

• Single-User License

This type of license limits the use of the software to only one user at a time. Most “commercial software” is distributed with a single-user license.

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Licensed Software

• Multi-User License

This type of license allows more than one person to use a particular software package. This type of license is beneficial in cases where users each requires their own personalized version of the software. Ex: electronic mail program.

• Concurrent-Use License

This license allows a certain number of copies of the software to be used at the same time.Ex: A company may use a word processor up to 5 users. This license are usually priced in Increments.

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Licensed Software

• Site License

This type of license generally allows the software to be used on any and all computers at a specific location, such as within a corporate office building or a university campus. A site license is priced at a flat rate. Ex. P 350,000.00 per site.

• Shareware

Shareware is copyrighted software marketed under a “try before you buy” policy. It usually includes a license that allows you to use the software for a trial period. If you want to use it beyond the trial period, you should send a registration fee. Typically you can make copies and give It to others. This will cause a low-cost marketing and distribution channel.

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Licensed Software

• Public Domain Software

This type of license is not protected by copyright because the copyright has expired, or the author has placed the program in public domain, making it available without restriction. It may be freely copied, distributed, and even resold. Its primary restriction is that you are not allowed to apply for a copyright on it.

• Freeware

It is a copyrighted software, which is available for free. The license for freeware permits you to use the software, copy it, and give it away; but does not permit you to alter it or sell it. Many utility programs, device drivers, and some games are available as freeware.

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Licensed Software

• Open Source Software

It makes the uncompiled program instructions available to programmers who want to modify and improve the software. Open source software may be sold or distributed free of charge, but it must include the uncompiled “source code.” Examples are Linux and FreeBSD.

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Unit 3.2 Application Software

Applications software (also called end-user programs) includes database programs, word processors, and spreadsheets. Figuratively speaking, applications software sits on top of systems software because it is unable to run without the operating system and system utilities.

In other words, applications software are merely tools to help the users (people) finish their day to day task.

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• Common Examples of Application software1. Documents (MS word, wordperfect)2. Database (SQL, MSaccess)3. Image (adobe PS, corel draw)4. Music and audio (mp3, realplayer)5. Games (war craft, counter strike)

Application Software

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Unit 3.3: Operating Systemsand Application

Operating System

Operating System is defined as a system software, which acts as the master controller for all the activities that take place within a computer system. An operating system is an integral part of virtually every computer system, including supercomputers, mainframes, servers, workstations, video game systems, handhelds, and personal computers.

The operating system interacts with application software, device drivers, and hardware to manage a computer’s resources. Resource refers to any component that is required to perform work.

The operating system allocates a specific area of RAM for each program that is open and running.

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Operating Systems

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Operating Systems

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An operating system acts as a filing clerk that stores and retrieves files from your disks and CDs. It remembers the names and locations of all your files, and keeps track of empty spaces where new files can be stored.

The operating system communicates with device driver software so that data can travel smoothly between the computer and these peripheral devices. It ensures that input and output proceeds in an orderly manner, using queues and buffers to collect and hold data while the computer is busy with other tasks.

Operating Systems

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Operating Systems

A user interface can be defined as the combination of hardware and software that helps people and computers communicate with each other. The computer’s user interface includes the mouse and keyboard that accept your input and carry out your commands, as well as display device that provides cues to help you use software, and displays error messages that alert you to problems. An operating system typically provides user interface tools, such as menus and toolbar buttons.

Most computers today feature a graphical user interface (GUI or gooey) provides a way to point and click a mouse to select menu options and manipulate graphical objects that are displayed in the screen.

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Operating Systems

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Operating Systems

The operating system program is quite large, so most of it is stored in the hard disk. The operating system’s small boot strap program is stored in ROM, and provides the instructions needed to load the core parts into memory when the system boots. It is a program in ROM and initializes the operating system on a computer.

The core part of the operating system called kernel provides the most essential operating system services, such as memory management and file access.

Other parts of the operating system, such as customization utilities are loaded into the memory as they are needed.

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Operating Systems

Utilities are helpful tools that you can use to control and customize your computer equipment and work environment.

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Operating Systems

Operating System Categories:• Single-User System – expects to deal with one set of input devices – those that can be controlled by one user at a time. Operating system for handheld computers and many personal computers fit into this category.• Multi-User System – designed to deal with input, output, and processing requests from many users all at the same time. One of its most difficult responsibilities is to schedule all of the processing requests that must be performed by a centralized computer.• Network Operating System – it is also referred to as “server computing system” provides communications and routing services that allow computers to share data, programs, and peripheral devices. Example is Novell.

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Operating Systems

• Multitasking Operating System – provides process and memory management services that allow two or more programs to run simultaneously. Most of today’s personal computer operating systems offer multitasking services.• Desktop Operating System – designed for personal computer. Examples are Windows ME or MAC OS. These operating systems are designed to accommodate a single user, but may also provide networking capability. Today’s desktop operating systems invariably provide multitasking capabilities.

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BIOS: Steps in Boot Process

Power-On

BIOS begins to execute initiates POST

Enables Video Card and Displays Information

Determine amount of DRAM

Perform Memory Test

Check Expansion Cards and Adapters

Initialize Expansion Cards and Adapters

Display System Information

Load OS thru Master Boot record 

Operating System Operational

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Unit 3.4 DOS Commands

Disk Operating System was developed by Microsoft and introduced on the original IBM PC in 1982. Although IBM called the operating system PC-DOS, Microsoft called it to other companies under then name MS-DOS.

Disk Operating System is a command-line user interface. MS-DOS 1.0 was released in 1981 for IBM computers and the latest version of MS-DOS is MS-DOS 6.22 released in 1994. While MS-DOS is not commonly used by itself today, it still can be accessed from Windows 95, Windows 98 or Windows ME by clicking Start / Run and typing command or CMD in Windows NT, 2000 or XP.

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• What is a path in DOS?

In DOS and Windows systems, a path is a list of directories where the operating system looks for executable files if it is unable to find the file in the working directory. You can specify the list of directories with the PATH command.

Path

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• Absolute pathAn absolute path name describes a file's location as a fixed address, beginning with the top (the server's name), and moving down to the file specified.

• Relative pathA relative path name describes the location of file (b) in relation to the location of the current file (a): whether it is seated in a folder above it, next to it (sharing the same folder), or in a folder below it. In all cases, the description is relative to the location of the current file.

Kinds of path

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Wildcards

• Files have unique names, but sometimes you might want to refer to more than one file.

• The asterisk (*) is a wild card character used to represent a group of characters in the filename or extension.

• The question mark (?) is a wild card character used to represent a single character in the filename or extension.

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DOS Commands

CD and CHDIR (Change Directory) is a command used to switch directories in MS-DOS.

Syntax:

CHDIR[drive:][path]CHDIR[..]CD[drive:][path]CD[..]

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DOS Commands

Examples:

cd\ - Goes to the highest level the root of the drive.

cd.. - Goes back one directory. For example if you are within the C:\WINDOWS\COMMAND> directory this would take you to C:\WINDOWS>

cd windows - If present would take you into the Windows directory. Windows can be substituted with any other name.

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DOS Commands

CLS is a command which allows the user to clear the complete contents of the screen and leave only a prompt.

Syntax:

CLS

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DOS Commands

COPY allows the user to copy one file from one source to another.

SYNTAX:

Copies one or more files to another location.

COPY [/A | /B] source [/A | /B] [+ source [/A | /B] [+ ...]] [destination] [/A | /B]] [/V] [/Y | /-Y]

Source Specifies the file or files to be copied./A Indicates an ASCII text file./B Indicates a binary file.

destination Specifies the directory and/or filename for the new file(s)./V Verifies that new files are written correctly./Y Suppresses prompting to confirm you want to overwrite an existing

destination file./-Y Causes prompting to confirm you want to overwrite an existing

destination file.

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DOS Commands

EXAMPLES:

copy *.* a: This would copy all files in the directory currently in to the floppy disk in drive a

copy autoexec.bat c:\windows This would take the autoexec.bat usually found at root and copy it into the windows directory the autoexec.bat can be substituted for any file(s).

copy win.ini c:\windows /y This would copy the win.ini file which is already in your windows directory to the windows directory without prompting if you wanted to overwrite the file or not.

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DOS Commands

Del which is short for delete and is a command used to delete files permanently from the computer.

SYNTAX

Deletes one or more files.

DEL [drive:][path]filename [/P]

ERASE [drive:][path]filename [/P]

[drive:][path]filename  Specifies the file(s) to delete. Specify multiple                          files by using wildcards.

 /P Prompts for confirmation before deleting each file.

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DOS Commands

EXAMPLES:del test.tmp Deletes the test.tmp in the directory that you currently are

in, if the file exists.

del c:\windows\test.tmp Delete the c:\windows\test.tmp in the windows directory if it

exists.

del c:\windows\temp\*.* (* is for wild character(s)) *.* indicates that you would like to

delete all files in the c:\windows\temp directory.

del c:\windows\temp\?est.tmp (? is a single wild character for one letter) This command

would delete any file ending with est.tmp such as pest.tmp or zest.tmp...

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DOS Commands

Deltree which is short for delete and is a command used to delete files permanently from the computer.

Deletes a directory and all the subdirectories and files in it.

To delete one or more files and directories: DELTREE [/Y] [drive:]path [[drive:]path[...]]

/Y Suppresses prompting to confirm you want to delete the subdirectory.

[drive:]path Specifies the name of the directory you want to delete.

EXAMPLE:

deltree c:\windows\fake010 = Deletes the fake010 directory and everything in it. 

Note: deltree command only works for Mircosoft Windows Me and previous versions. For Windows XP, deltree’s functionality is combined already at rd command.

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DOS Commands

The dir command allows you to see the available files in the current and or parent directories.

SYNTAX:

Displays a list of files and subdirectories in a directory.

DIR [drive:][path][filename] [/P] [/W] [/A[[:]attributes]] [/O[[:]sortorder]] [/S] [/B] [/L] [/V]

[drive:][path][filename] Specifies drive, directory, and/or files to list. (Could be enhanced file specification or multiple filespecs.)/P Pauses after each screenful of information./W Uses wide list format.

D Directories R Read-only files

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DOS Commands

/A attributes:H Hidden files A Files ready for archivingS System files - Prefix meaning notList by files in sorted order, sortorder:N By name (alphabetic) S By size (smallest first)

/O E By extension (alphabetic) D By date & time (earliest first)G Group directories first - Prefix to reverse orderA By Last Access Date (earliest first)

/S Displays files in specified directory and all subdirectories./B Uses bare format (no heading information or summary)./L Uses lowercase./V Verbose mode.

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DOS Commands

EXAMPLES:

dir = Lists all files and directories in the directory that you are currently in.

dir /s = Lists the files in the directory that you are in and all sub directories after that directory, if you are at root "C:\>" and type this command this will list to you every file and directory that is on the computer.

dir /p = If the directory has a lot of files and you cannot read all the files you can use this command and it will display all files one page at a time.

dir /w = If you don't need the info on the date / time and other information on the files you can use this command to list just the files and directories going horizontal taking as little as space needed.

dir /s /w /p = This would list all the files and directories in the current directory and the sub directories after that in wide format one page at a time.

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DOS Commands

The move command allows you to move files or directories from one folder to another or from one drive to another.

Syntax:

Moves files and renames files and directories.

•To move one or more files: MOVE [/Y | /-Y] [drive:][path]filename1[,...] destination

•To rename a directory: MOVE [/Y | /-Y] [drive:][path]dirname1 dirname2 [drive:][path]

filename1 Specifies the location and name of the file or files you want to move. Destination Specifies the new location of the file. Destination can consist of a drive letter and colon, a directory name, or a combination.

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DOS Commands

If you are moving only one file, you can also include a filename if you want to rename the file when you move it. [drive:][path]dirname1 Specifies the directory you want to rename. dirname2 Specifies the new name of the directory. /Y Suppresses prompting to confirm creation of a directory or overwriting of the destination. /-Y Causes prompting to confirm creation of a directory or overwriting of the destination.

Example:

move c:\windows\temp\*.* c:\temp - This would move the files of c:\windows\temp to the temp directory in root, this is of course assuming you have the windows\temp directory. 

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DOS Commands

RMDIR or RD removes empty directories in DOS. To delete directories with files or directories within them the user must use the deltree command.

SYNTAX:

Removes (deletes) a directory.

RMDIR [drive:]pathRD [drive:]path

EXAMPLE:

rmdir c:\test - This would remove the test directory if empty if you want to delete directories that are full use the deltree command.

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DOS Commands

REN or RENAME used to rename files and directories from the original name to a new name.In earlier releases of MS-DOS instead of using ren or rename you need to use the move command to rename your MS-DOS directories or files.

SYNTAX:

Renames a file/directory or files/directories.

RENAME [drive:][path][directoryname1 | filename1] [directoryname2 | filename2]

REN [drive:][path][directoryname1 | filename1] [directoryname2 | filename2]

Note that you cannot specify a new drive or path for your destination.

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DOS Commands

EXAMPLES:

rename c:\chope hope - Rename the directory chope to hope. 

rename *.txt *.bak - Rename all text files to files with .bak extension.

rename * 1_* - Rename all files to begin with 1_. The asterisk (*) in this example is an example of a wild character because nothing was placed before or after the first asterisk this means all files.

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DOS Commands

MD allows you to create your own directories in DOS.

SYNTAX:

Creates a directory.

MKDIR [drive:]pathMD [drive:]path

EXAMPLE:

md test - This would make a test directory in the directory that you are currently in.